diff --git a/compiler/rustc_codegen_gcc/src/builder.rs b/compiler/rustc_codegen_gcc/src/builder.rs
index 6573b5b165e61..805039625bda2 100644
--- a/compiler/rustc_codegen_gcc/src/builder.rs
+++ b/compiler/rustc_codegen_gcc/src/builder.rs
@@ -1686,6 +1686,13 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
// FIXME(bjorn3): implement
}
+ fn set_tail_call(&mut self, _call_inst: RValue<'gcc>) {
+ // Explicitly fail when this method is called
+ bug!(
+ "Guaranteed tail calls with the 'become' keyword are not implemented in the GCC backend"
+ );
+ }
+
fn set_span(&mut self, _span: Span) {}
fn from_immediate(&mut self, val: Self::Value) -> Self::Value {
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 55d34f5f2efe2..f084f11ddfd99 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -1419,6 +1419,11 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
let cold_inline = llvm::AttributeKind::Cold.create_attr(self.llcx);
attributes::apply_to_callsite(llret, llvm::AttributePlace::Function, &[cold_inline]);
}
+
+ fn set_tail_call(&mut self, call_inst: &'ll Value) {
+ // LLVMSetTailCall is marked as safe in the FFI definition
+ llvm::LLVMSetTailCall(call_inst, llvm::True);
+ }
}
impl<'ll> StaticBuilderMethods for Builder<'_, 'll, '_> {
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 6d1930a402d37..c65fdd4653ca2 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -342,6 +342,90 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
/// Codegen implementations for some terminator variants.
impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
+ fn codegen_tail_call_terminator(
+ &mut self,
+ bx: &mut Bx,
+ func: &mir::Operand<'tcx>,
+ args: &[Spanned<mir::Operand<'tcx>>],
+ fn_span: Span,
+ ) {
+ // We don't need source_info as we already have fn_span for diagnostics
+ let func = self.codegen_operand(bx, func);
+ let fn_ty = func.layout.ty;
+
+ // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
+ let (fn_ptr, fn_abi, instance) = match *fn_ty.kind() {
+ ty::FnDef(def_id, substs) => {
+ let instance = ty::Instance::expect_resolve(
+ bx.tcx(),
+ bx.typing_env(),
+ def_id,
+ substs,
+ fn_span,
+ );
+ let fn_ptr = bx.get_fn_addr(instance);
+ let fn_abi = bx.fn_abi_of_instance(instance, ty::List::empty());
+ (fn_ptr, fn_abi, Some(instance))
+ }
+ ty::FnPtr(..) => {
+ let sig = fn_ty.fn_sig(bx.tcx());
+ let extra_args = bx.tcx().mk_type_list(&[]);
+ let fn_ptr = func.immediate();
+ let fn_abi = bx.fn_abi_of_fn_ptr(sig, extra_args);
+ (fn_ptr, fn_abi, None)
+ }
+ _ => bug!("{} is not callable", func.layout.ty),
+ };
+
+ let mut llargs = Vec::with_capacity(args.len());
+
+ // Process arguments
+ for arg in args {
+ let op = self.codegen_operand(bx, &arg.node);
+ let arg_idx = llargs.len();
+
+ if arg_idx < fn_abi.args.len() {
+ self.codegen_argument(bx, op, &mut llargs, &fn_abi.args[arg_idx]);
+ } else {
+ // This can happen in case of C-variadic functions
+ let is_immediate = match op.val {
+ Immediate(_) => true,
+ _ => false,
+ };
+
+ if is_immediate {
+ llargs.push(op.immediate());
+ } else {
+ let temp = PlaceRef::alloca(bx, op.layout);
+ op.val.store(bx, temp);
+ llargs.push(bx.load(
+ bx.backend_type(op.layout),
+ temp.val.llval,
+ temp.val.align,
+ ));
+ }
+ }
+ }
+
+ // Call the function
+ let fn_ty = bx.fn_decl_backend_type(fn_abi);
+ let fn_attrs = if let Some(instance) = instance
+ && bx.tcx().def_kind(instance.def_id()).has_codegen_attrs()
+ {
+ Some(bx.tcx().codegen_fn_attrs(instance.def_id()))
+ } else {
+ None
+ };
+
+ // Perform the actual function call
+ let llret = bx.call(fn_ty, fn_attrs, Some(fn_abi), fn_ptr, &llargs, None, instance);
+
+ // Mark as tail call - this is the critical part
+ bx.set_tail_call(llret);
+
+ // Return the result
+ bx.ret(llret);
+ }
/// Generates code for a `Resume` terminator.
fn codegen_resume_terminator(&mut self, helper: TerminatorCodegenHelper<'tcx>, bx: &mut Bx) {
if let Some(funclet) = helper.funclet(self) {
@@ -1430,12 +1514,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
fn_span,
mergeable_succ(),
),
- mir::TerminatorKind::TailCall { .. } => {
- // FIXME(explicit_tail_calls): implement tail calls in ssa backend
- span_bug!(
- terminator.source_info.span,
- "`TailCall` terminator is not yet supported by `rustc_codegen_ssa`"
- )
+ mir::TerminatorKind::TailCall { ref func, ref args, fn_span } => {
+ self.codegen_tail_call_terminator(bx, func, args, fn_span);
+ MergingSucc::False
}
mir::TerminatorKind::CoroutineDrop | mir::TerminatorKind::Yield { .. } => {
bug!("coroutine ops in codegen")
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 5f91133d5b47e..f698810f7a359 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -555,6 +555,10 @@ pub trait BuilderMethods<'a, 'tcx>:
funclet: Option<&Self::Funclet>,
instance: Option<Instance<'tcx>>,
) -> Self::Value;
+
+ /// Mark a call instruction as a tail call (guaranteed tail call optimization)
+ /// Used for implementing the `become` expression
+ fn set_tail_call(&mut self, call_inst: Self::Value);
fn zext(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
fn apply_attrs_to_cleanup_callsite(&mut self, llret: Self::Value);
diff --git a/tests/run-make/tail-call-llvm-ir/Makefile b/tests/run-make/tail-call-llvm-ir/Makefile
new file mode 100644
index 0000000000000..8c7138e6ca113
--- /dev/null
+++ b/tests/run-make/tail-call-llvm-ir/Makefile
@@ -0,0 +1,26 @@
+# This test verifies that the `become` keyword generates tail call instructions in LLVM IR
+
+# Use the Rust compiler from the build directory
+RUSTC ?= ../../../build/aarch64-apple-darwin/stage1/bin/rustc
+
+all: verify-tail-call
+
+verify-tail-call:
+ # Create test file with debuginfo to ensure function names are preserved
+ $(RUSTC) tail-call-test.rs --emit=llvm-ir -g -C opt-level=0
+
+ # Check that `become` generates 'tail call' instructions for with_tail function
+ grep -q "tail call.*@_ZN14tail_call_test9with_tail" tail-call-test.ll || (echo "ERROR: 'tail call' instruction not found for with_tail"; exit 1)
+
+ # Check that regular recursive calls don't use tail call optimization by default
+ grep -q "@_ZN14tail_call_test7no_tail" tail-call-test.ll || (echo "ERROR: no_tail function not found"; exit 1)
+ ! grep -q "tail call.*@_ZN14tail_call_test7no_tail" tail-call-test.ll || (echo "ERROR: Regular function call incorrectly marked as tail call"; exit 1)
+
+ # Check mutual recursion with 'become'
+ grep -q "tail call.*@_ZN14tail_call_test14even_with_tail" tail-call-test.ll || (echo "ERROR: 'tail call' instruction not found for even_with_tail"; exit 1)
+ grep -q "tail call.*@_ZN14tail_call_test13odd_with_tail" tail-call-test.ll || (echo "ERROR: 'tail call' instruction not found for odd_with_tail"; exit 1)
+
+ # The test passes only if all checks above confirm that:
+ # 1. Functions using 'become' generate LLVM tail call instructions
+ # 2. Regular recursive functions don't generate tail call instructions
+ @echo "LLVM IR verification successful: 'become' correctly generates 'tail call' instructions"
\ No newline at end of file
diff --git a/tests/run-make/tail-call-llvm-ir/tail-call-test.ll b/tests/run-make/tail-call-llvm-ir/tail-call-test.ll
new file mode 100644
index 0000000000000..4510a5e9364ba
--- /dev/null
+++ b/tests/run-make/tail-call-llvm-ir/tail-call-test.ll
@@ -0,0 +1,1068 @@
+; ModuleID = 'tail_call_test.7c02b6d4e63aa8f0-cgu.0'
+source_filename = "tail_call_test.7c02b6d4e63aa8f0-cgu.0"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
+target triple = "arm64-apple-macosx11.0.0"
+
+%"core::fmt::rt::Argument<'_>" = type { %"core::fmt::rt::ArgumentType<'_>" }
+%"core::fmt::rt::ArgumentType<'_>" = type { ptr, [1 x i64] }
+
+@vtable.0 = private constant <{ [24 x i8], ptr, ptr, ptr }> <{ [24 x i8] c"\00\00\00\00\00\00\00\00\08\00\00\00\00\00\00\00\08\00\00\00\00\00\00\00", ptr @"_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h4fa86179f7747905E", ptr @"_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h9631b88370906e50E", ptr @"_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h9631b88370906e50E" }>, align 8, !dbg !0
+@anon.8f6558de37f42f53bff2af1f8e7dc9d8.0 = private unnamed_addr constant <{ [8 x i8], [8 x i8] }> <{ [8 x i8] zeroinitializer, [8 x i8] undef }>, align 8
+@alloc_73a0fade79f6dec35d3a164188d3f328 = private unnamed_addr constant <{ [17 x i8] }> <{ [17 x i8] c"tail-call-test.rs" }>, align 1
+@alloc_5813a272eb42ea3a81a9088a043c1814 = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\00\09\00\00\00\1A\00\00\00" }>, align 8
+@alloc_701437b71fb12e826cca45d25bf54394 = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\00\13\00\00\00\11\00\00\00" }>, align 8
+@alloc_24e0902b97ab05744658dee33cfad6bd = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\00\1C\00\00\00#\00\00\00" }>, align 8
+@alloc_381b85d74f28f9e668d3c070c2e3af56 = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\00#\00\00\00$\00\00\00" }>, align 8
+@alloc_8f8fd5dbae8400c38e1639b7ea801d16 = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\00,\00\00\00\1A\00\00\00" }>, align 8
+@alloc_911aa589553e6649ae5da752650f3354 = private unnamed_addr constant <{ ptr, [16 x i8] }> <{ ptr @alloc_73a0fade79f6dec35d3a164188d3f328, [16 x i8] c"\11\00\00\00\00\00\00\003\00\00\00\1B\00\00\00" }>, align 8
+@alloc_932e95a4c1bb019d25afba309491f49d = private unnamed_addr constant <{ [9 x i8] }> <{ [9 x i8] c"Results: " }>, align 1
+@alloc_0242e8ee118de705af76c627590b82cc = private unnamed_addr constant <{ [1 x i8] }> <{ [1 x i8] c" " }>, align 1
+@alloc_49a1e817e911805af64bbc7efb390101 = private unnamed_addr constant <{ [1 x i8] }> <{ [1 x i8] c"\0A" }>, align 1
+@alloc_70b8f01ca3944289d1c53010fd7cc68a = private unnamed_addr constant <{ ptr, [8 x i8], ptr, [8 x i8], ptr, [8 x i8], ptr, [8 x i8], ptr, [8 x i8], ptr, [8 x i8], ptr, [8 x i8] }> <{ ptr @alloc_932e95a4c1bb019d25afba309491f49d, [8 x i8] c"\09\00\00\00\00\00\00\00", ptr @alloc_0242e8ee118de705af76c627590b82cc, [8 x i8] c"\01\00\00\00\00\00\00\00", ptr @alloc_0242e8ee118de705af76c627590b82cc, [8 x i8] c"\01\00\00\00\00\00\00\00", ptr @alloc_0242e8ee118de705af76c627590b82cc, [8 x i8] c"\01\00\00\00\00\00\00\00", ptr @alloc_0242e8ee118de705af76c627590b82cc, [8 x i8] c"\01\00\00\00\00\00\00\00", ptr @alloc_0242e8ee118de705af76c627590b82cc, [8 x i8] c"\01\00\00\00\00\00\00\00", ptr @alloc_49a1e817e911805af64bbc7efb390101, [8 x i8] c"\01\00\00\00\00\00\00\00" }>, align 8
+
+; std::rt::lang_start
+; Function Attrs: uwtable
+define hidden i64 @_ZN3std2rt10lang_start17h73b0c5d8223deb96E(ptr %main, i64 %argc, ptr %argv, i8 %sigpipe) unnamed_addr #0 !dbg !45 {
+start:
+ %sigpipe.dbg.spill = alloca [1 x i8], align 1
+ %argv.dbg.spill = alloca [8 x i8], align 8
+ %argc.dbg.spill = alloca [8 x i8], align 8
+ %main.dbg.spill = alloca [8 x i8], align 8
+ %_7 = alloca [8 x i8], align 8
+ store ptr %main, ptr %main.dbg.spill, align 8
+ #dbg_declare(ptr %main.dbg.spill, !53, !DIExpression(), !59)
+ store i64 %argc, ptr %argc.dbg.spill, align 8
+ #dbg_declare(ptr %argc.dbg.spill, !54, !DIExpression(), !60)
+ store ptr %argv, ptr %argv.dbg.spill, align 8
+ #dbg_declare(ptr %argv.dbg.spill, !55, !DIExpression(), !61)
+ store i8 %sigpipe, ptr %sigpipe.dbg.spill, align 1
+ #dbg_declare(ptr %sigpipe.dbg.spill, !56, !DIExpression(), !62)
+ store ptr %main, ptr %_7, align 8, !dbg !63
+; call std::rt::lang_start_internal
+ %_0 = call i64 @_ZN3std2rt19lang_start_internal17hff478237ff51a9c7E(ptr align 1 %_7, ptr align 8 @vtable.0, i64 %argc, ptr %argv, i8 %sigpipe), !dbg !64
+ ret i64 %_0, !dbg !65
+}
+
+; std::rt::lang_start::{{closure}}
+; Function Attrs: inlinehint uwtable
+define internal i32 @"_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h9631b88370906e50E"(ptr align 8 %_1) unnamed_addr #1 !dbg !66 {
+start:
+ %self.dbg.spill = alloca [1 x i8], align 1
+ %_1.dbg.spill = alloca [8 x i8], align 8
+ store ptr %_1, ptr %_1.dbg.spill, align 8
+ #dbg_declare(ptr %_1.dbg.spill, !72, !DIExpression(DW_OP_deref), !73)
+ %_4 = load ptr, ptr %_1, align 8, !dbg !74
+; call std::sys::backtrace::__rust_begin_short_backtrace
+ call void @_ZN3std3sys9backtrace28__rust_begin_short_backtrace17hac99c3a0f565fd14E(ptr %_4), !dbg !75
+; call <() as std::process::Termination>::report
+ %self = call i8 @"_ZN54_$LT$$LP$$RP$$u20$as$u20$std..process..Termination$GT$6report17hccf942a05a23072aE"(), !dbg !75
+ store i8 %self, ptr %self.dbg.spill, align 1, !dbg !75
+ #dbg_declare(ptr %self.dbg.spill, !76, !DIExpression(), !95)
+ %_0 = zext i8 %self to i32, !dbg !97
+ ret i32 %_0, !dbg !105
+}
+
+; std::sys::backtrace::__rust_begin_short_backtrace
+; Function Attrs: noinline uwtable
+define internal void @_ZN3std3sys9backtrace28__rust_begin_short_backtrace17hac99c3a0f565fd14E(ptr %f) unnamed_addr #2 !dbg !106 {
+start:
+ %dummy.dbg.spill = alloca [0 x i8], align 1
+ %f.dbg.spill = alloca [8 x i8], align 8
+ %result.dbg.spill = alloca [0 x i8], align 1
+ #dbg_declare(ptr %result.dbg.spill, !113, !DIExpression(), !117)
+ store ptr %f, ptr %f.dbg.spill, align 8
+ #dbg_declare(ptr %f.dbg.spill, !112, !DIExpression(), !118)
+ #dbg_declare(ptr %dummy.dbg.spill, !119, !DIExpression(), !126)
+; call core::ops::function::FnOnce::call_once
+ call void @_ZN4core3ops8function6FnOnce9call_once17hfd4f30177a814130E(ptr %f), !dbg !128
+ call void asm sideeffect "", "~{memory}"(), !dbg !129, !srcloc !130
+ ret void, !dbg !131
+}
+
+; core::fmt::rt::Argument::new_display
+; Function Attrs: inlinehint uwtable
+define internal void @_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE(ptr sret([16 x i8]) align 8 %_0, ptr align 1 %x) unnamed_addr #1 !dbg !132 {
+start:
+ %x.dbg.spill = alloca [8 x i8], align 8
+ %_3 = alloca [16 x i8], align 8
+ store ptr %x, ptr %x.dbg.spill, align 8
+ #dbg_declare(ptr %x.dbg.spill, !243, !DIExpression(), !244)
+ #dbg_declare(ptr %x.dbg.spill, !245, !DIExpression(), !254)
+ #dbg_declare(ptr %x.dbg.spill, !256, !DIExpression(), !267)
+ store ptr %x, ptr %_3, align 8, !dbg !269
+ %0 = getelementptr inbounds i8, ptr %_3, i64 8, !dbg !269
+ store ptr @"_ZN43_$LT$bool$u20$as$u20$core..fmt..Display$GT$3fmt17hd249e77bcd60ee87E", ptr %0, align 8, !dbg !269
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %_0, ptr align 8 %_3, i64 16, i1 false), !dbg !270
+ ret void, !dbg !271
+}
+
+; core::fmt::rt::Argument::new_display
+; Function Attrs: inlinehint uwtable
+define internal void @_ZN4core3fmt2rt8Argument11new_display17ha8da45a5453b2abdE(ptr sret([16 x i8]) align 8 %_0, ptr align 4 %x) unnamed_addr #1 !dbg !272 {
+start:
+ %x.dbg.spill = alloca [8 x i8], align 8
+ %_3 = alloca [16 x i8], align 8
+ store ptr %x, ptr %x.dbg.spill, align 8
+ #dbg_declare(ptr %x.dbg.spill, !280, !DIExpression(), !281)
+ #dbg_declare(ptr %x.dbg.spill, !282, !DIExpression(), !291)
+ #dbg_declare(ptr %x.dbg.spill, !293, !DIExpression(), !303)
+ store ptr %x, ptr %_3, align 8, !dbg !305
+ %0 = getelementptr inbounds i8, ptr %_3, i64 8, !dbg !305
+ store ptr @"_ZN4core3fmt3num3imp52_$LT$impl$u20$core..fmt..Display$u20$for$u20$u32$GT$3fmt17h2d6296303bc86543E", ptr %0, align 8, !dbg !305
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %_0, ptr align 8 %_3, i64 16, i1 false), !dbg !306
+ ret void, !dbg !307
+}
+
+; core::fmt::Arguments::new_v1
+; Function Attrs: inlinehint uwtable
+define internal void @_ZN4core3fmt9Arguments6new_v117h7b06876a57e3281cE(ptr sret([48 x i8]) align 8 %_0, ptr align 8 %pieces, ptr align 8 %args) unnamed_addr #1 !dbg !308 {
+start:
+ %args.dbg.spill = alloca [8 x i8], align 8
+ %pieces.dbg.spill = alloca [8 x i8], align 8
+ store ptr %pieces, ptr %pieces.dbg.spill, align 8
+ #dbg_declare(ptr %pieces.dbg.spill, !381, !DIExpression(), !383)
+ store ptr %args, ptr %args.dbg.spill, align 8
+ #dbg_declare(ptr %args.dbg.spill, !382, !DIExpression(), !384)
+ store ptr %pieces, ptr %_0, align 8, !dbg !385
+ %0 = getelementptr inbounds i8, ptr %_0, i64 8, !dbg !385
+ store i64 7, ptr %0, align 8, !dbg !385
+ %1 = load ptr, ptr @anon.8f6558de37f42f53bff2af1f8e7dc9d8.0, align 8, !dbg !385
+ %2 = load i64, ptr getelementptr inbounds (i8, ptr @anon.8f6558de37f42f53bff2af1f8e7dc9d8.0, i64 8), align 8, !dbg !385
+ %3 = getelementptr inbounds i8, ptr %_0, i64 32, !dbg !385
+ store ptr %1, ptr %3, align 8, !dbg !385
+ %4 = getelementptr inbounds i8, ptr %3, i64 8, !dbg !385
+ store i64 %2, ptr %4, align 8, !dbg !385
+ %5 = getelementptr inbounds i8, ptr %_0, i64 16, !dbg !385
+ store ptr %args, ptr %5, align 8, !dbg !385
+ %6 = getelementptr inbounds i8, ptr %5, i64 8, !dbg !385
+ store i64 6, ptr %6, align 8, !dbg !385
+ ret void, !dbg !386
+}
+
+; core::ops::function::FnOnce::call_once{{vtable.shim}}
+; Function Attrs: inlinehint uwtable
+define internal i32 @"_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h4fa86179f7747905E"(ptr %_1) unnamed_addr #1 !dbg !387 {
+start:
+ %_1.dbg.spill = alloca [8 x i8], align 8
+ %_2 = alloca [0 x i8], align 1
+ store ptr %_1, ptr %_1.dbg.spill, align 8
+ #dbg_declare(ptr %_1.dbg.spill, !396, !DIExpression(), !401)
+ #dbg_declare(ptr %_2, !397, !DIExpression(), !401)
+ %0 = load ptr, ptr %_1, align 8, !dbg !401
+; call core::ops::function::FnOnce::call_once
+ %_0 = call i32 @_ZN4core3ops8function6FnOnce9call_once17ha95bcc209a0f6c7cE(ptr %0), !dbg !401
+ ret i32 %_0, !dbg !401
+}
+
+; core::ops::function::FnOnce::call_once
+; Function Attrs: inlinehint uwtable
+define internal i32 @_ZN4core3ops8function6FnOnce9call_once17ha95bcc209a0f6c7cE(ptr %0) unnamed_addr #1 personality ptr @rust_eh_personality !dbg !402 {
+start:
+ %1 = alloca [16 x i8], align 8
+ %_2 = alloca [0 x i8], align 1
+ %_1 = alloca [8 x i8], align 8
+ store ptr %0, ptr %_1, align 8
+ #dbg_declare(ptr %_1, !406, !DIExpression(), !408)
+ #dbg_declare(ptr %_2, !407, !DIExpression(), !408)
+; invoke std::rt::lang_start::{{closure}}
+ %_0 = invoke i32 @"_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h9631b88370906e50E"(ptr align 8 %_1)
+ to label %bb1 unwind label %cleanup, !dbg !408
+
+bb3: ; preds = %cleanup
+ %2 = load ptr, ptr %1, align 8, !dbg !408
+ %3 = getelementptr inbounds i8, ptr %1, i64 8, !dbg !408
+ %4 = load i32, ptr %3, align 8, !dbg !408
+ %5 = insertvalue { ptr, i32 } poison, ptr %2, 0, !dbg !408
+ %6 = insertvalue { ptr, i32 } %5, i32 %4, 1, !dbg !408
+ resume { ptr, i32 } %6, !dbg !408
+
+cleanup: ; preds = %start
+ %7 = landingpad { ptr, i32 }
+ cleanup
+ %8 = extractvalue { ptr, i32 } %7, 0
+ %9 = extractvalue { ptr, i32 } %7, 1
+ store ptr %8, ptr %1, align 8
+ %10 = getelementptr inbounds i8, ptr %1, i64 8
+ store i32 %9, ptr %10, align 8
+ br label %bb3
+
+bb1: ; preds = %start
+ ret i32 %_0, !dbg !408
+}
+
+; core::ops::function::FnOnce::call_once
+; Function Attrs: inlinehint uwtable
+define internal void @_ZN4core3ops8function6FnOnce9call_once17hfd4f30177a814130E(ptr %_1) unnamed_addr #1 !dbg !409 {
+start:
+ %_1.dbg.spill = alloca [8 x i8], align 8
+ %_2 = alloca [0 x i8], align 1
+ store ptr %_1, ptr %_1.dbg.spill, align 8
+ #dbg_declare(ptr %_1.dbg.spill, !411, !DIExpression(), !415)
+ #dbg_declare(ptr %_2, !412, !DIExpression(), !415)
+ call void %_1(), !dbg !415
+ ret void, !dbg !415
+}
+
+; core::ptr::drop_in_place<std::rt::lang_start<()>::{{closure}}>
+; Function Attrs: inlinehint uwtable
+define internal void @"_ZN4core3ptr85drop_in_place$LT$std..rt..lang_start$LT$$LP$$RP$$GT$..$u7b$$u7b$closure$u7d$$u7d$$GT$17h2dc5dcfe3d451b5dE"(ptr align 8 %_1) unnamed_addr #1 !dbg !416 {
+start:
+ %_1.dbg.spill = alloca [8 x i8], align 8
+ store ptr %_1, ptr %_1.dbg.spill, align 8
+ #dbg_declare(ptr %_1.dbg.spill, !421, !DIExpression(), !424)
+ ret void, !dbg !424
+}
+
+; <() as std::process::Termination>::report
+; Function Attrs: inlinehint uwtable
+define internal i8 @"_ZN54_$LT$$LP$$RP$$u20$as$u20$std..process..Termination$GT$6report17hccf942a05a23072aE"() unnamed_addr #1 !dbg !425 {
+start:
+ %_1.dbg.spill = alloca [0 x i8], align 1
+ #dbg_declare(ptr %_1.dbg.spill, !430, !DIExpression(), !431)
+ ret i8 0, !dbg !432
+}
+
+; tail_call_test::with_tail
+; Function Attrs: uwtable
+define internal i32 @_ZN14tail_call_test9with_tail17hc3aece45eddbb180E(i32 %n) unnamed_addr #0 !dbg !433 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !439, !DIExpression(), !440)
+ %0 = icmp eq i32 %n, 0, !dbg !441
+ br i1 %0, label %bb1, label %bb2, !dbg !441
+
+bb1: ; preds = %start
+ ret i32 0, !dbg !442
+
+bb2: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !443
+ %_3.1 = icmp ult i32 %n, 1, !dbg !443
+ br i1 %_3.1, label %panic, label %bb3, !dbg !443
+
+bb3: ; preds = %bb2
+; call tail_call_test::with_tail
+ %1 = tail call i32 @_ZN14tail_call_test9with_tail17hc3aece45eddbb180E(i32 %_3.0), !dbg !444
+ ret i32 %1, !dbg !444
+
+panic: ; preds = %bb2
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_5813a272eb42ea3a81a9088a043c1814) #7, !dbg !443
+ unreachable, !dbg !443
+}
+
+; tail_call_test::no_tail
+; Function Attrs: uwtable
+define internal i32 @_ZN14tail_call_test7no_tail17h8d6adcb9d9b56776E(i32 %n) unnamed_addr #0 !dbg !445 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ %_0 = alloca [4 x i8], align 4
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !447, !DIExpression(), !448)
+ %0 = icmp eq i32 %n, 0, !dbg !449
+ br i1 %0, label %bb1, label %bb2, !dbg !449
+
+bb1: ; preds = %start
+ store i32 0, ptr %_0, align 4, !dbg !450
+ br label %bb4, !dbg !451
+
+bb2: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !452
+ %_3.1 = icmp ult i32 %n, 1, !dbg !452
+ br i1 %_3.1, label %panic, label %bb3, !dbg !452
+
+bb4: ; preds = %bb3, %bb1
+ %1 = load i32, ptr %_0, align 4, !dbg !453
+ ret i32 %1, !dbg !453
+
+bb3: ; preds = %bb2
+; call tail_call_test::no_tail
+ %2 = call i32 @_ZN14tail_call_test7no_tail17h8d6adcb9d9b56776E(i32 %_3.0), !dbg !454
+ store i32 %2, ptr %_0, align 4, !dbg !454
+ br label %bb4, !dbg !454
+
+panic: ; preds = %bb2
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_701437b71fb12e826cca45d25bf54394) #7, !dbg !452
+ unreachable, !dbg !452
+}
+
+; tail_call_test::even_with_tail
+; Function Attrs: uwtable
+define internal zeroext i1 @_ZN14tail_call_test14even_with_tail17h8d1dbeb6515757cfE(i32 %n) unnamed_addr #0 !dbg !455 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !459, !DIExpression(), !460)
+ %0 = icmp eq i32 %n, 0, !dbg !461
+ br i1 %0, label %bb2, label %bb1, !dbg !461
+
+bb2: ; preds = %start
+ ret i1 true, !dbg !462
+
+bb1: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !463
+ %_3.1 = icmp ult i32 %n, 1, !dbg !463
+ br i1 %_3.1, label %panic, label %bb3, !dbg !463
+
+bb3: ; preds = %bb1
+; call tail_call_test::odd_with_tail
+ %1 = tail call zeroext i1 @_ZN14tail_call_test13odd_with_tail17hc95516150aaddcc1E(i32 %_3.0), !dbg !464
+ ret i1 %1, !dbg !464
+
+panic: ; preds = %bb1
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_24e0902b97ab05744658dee33cfad6bd) #7, !dbg !463
+ unreachable, !dbg !463
+}
+
+; tail_call_test::odd_with_tail
+; Function Attrs: uwtable
+define internal zeroext i1 @_ZN14tail_call_test13odd_with_tail17hc95516150aaddcc1E(i32 %n) unnamed_addr #0 !dbg !465 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !467, !DIExpression(), !468)
+ %0 = icmp eq i32 %n, 0, !dbg !469
+ br i1 %0, label %bb2, label %bb1, !dbg !469
+
+bb2: ; preds = %start
+ ret i1 false, !dbg !470
+
+bb1: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !471
+ %_3.1 = icmp ult i32 %n, 1, !dbg !471
+ br i1 %_3.1, label %panic, label %bb3, !dbg !471
+
+bb3: ; preds = %bb1
+; call tail_call_test::even_with_tail
+ %1 = tail call zeroext i1 @_ZN14tail_call_test14even_with_tail17h8d1dbeb6515757cfE(i32 %_3.0), !dbg !472
+ ret i1 %1, !dbg !472
+
+panic: ; preds = %bb1
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_381b85d74f28f9e668d3c070c2e3af56) #7, !dbg !471
+ unreachable, !dbg !471
+}
+
+; tail_call_test::even_no_tail
+; Function Attrs: uwtable
+define internal zeroext i1 @_ZN14tail_call_test12even_no_tail17hd3be8e5729868b97E(i32 %n) unnamed_addr #0 !dbg !473 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ %_0 = alloca [1 x i8], align 1
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !475, !DIExpression(), !476)
+ %0 = icmp eq i32 %n, 0, !dbg !477
+ br i1 %0, label %bb2, label %bb1, !dbg !477
+
+bb2: ; preds = %start
+ store i8 1, ptr %_0, align 1, !dbg !478
+ br label %bb4, !dbg !478
+
+bb1: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !479
+ %_3.1 = icmp ult i32 %n, 1, !dbg !479
+ br i1 %_3.1, label %panic, label %bb3, !dbg !479
+
+bb4: ; preds = %bb3, %bb2
+ %1 = load i8, ptr %_0, align 1, !dbg !480
+ %2 = trunc nuw i8 %1 to i1, !dbg !480
+ ret i1 %2, !dbg !480
+
+bb3: ; preds = %bb1
+; call tail_call_test::odd_no_tail
+ %3 = call zeroext i1 @_ZN14tail_call_test11odd_no_tail17h1399b4ae4de50274E(i32 %_3.0), !dbg !481
+ %4 = zext i1 %3 to i8, !dbg !481
+ store i8 %4, ptr %_0, align 1, !dbg !481
+ br label %bb4, !dbg !481
+
+panic: ; preds = %bb1
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_8f8fd5dbae8400c38e1639b7ea801d16) #7, !dbg !479
+ unreachable, !dbg !479
+}
+
+; tail_call_test::odd_no_tail
+; Function Attrs: uwtable
+define internal zeroext i1 @_ZN14tail_call_test11odd_no_tail17h1399b4ae4de50274E(i32 %n) unnamed_addr #0 !dbg !482 {
+start:
+ %n.dbg.spill = alloca [4 x i8], align 4
+ %_0 = alloca [1 x i8], align 1
+ store i32 %n, ptr %n.dbg.spill, align 4
+ #dbg_declare(ptr %n.dbg.spill, !484, !DIExpression(), !485)
+ %0 = icmp eq i32 %n, 0, !dbg !486
+ br i1 %0, label %bb2, label %bb1, !dbg !486
+
+bb2: ; preds = %start
+ store i8 0, ptr %_0, align 1, !dbg !487
+ br label %bb4, !dbg !487
+
+bb1: ; preds = %start
+ %_3.0 = sub i32 %n, 1, !dbg !488
+ %_3.1 = icmp ult i32 %n, 1, !dbg !488
+ br i1 %_3.1, label %panic, label %bb3, !dbg !488
+
+bb4: ; preds = %bb3, %bb2
+ %1 = load i8, ptr %_0, align 1, !dbg !489
+ %2 = trunc nuw i8 %1 to i1, !dbg !489
+ ret i1 %2, !dbg !489
+
+bb3: ; preds = %bb1
+; call tail_call_test::even_no_tail
+ %3 = call zeroext i1 @_ZN14tail_call_test12even_no_tail17hd3be8e5729868b97E(i32 %_3.0), !dbg !490
+ %4 = zext i1 %3 to i8, !dbg !490
+ store i8 %4, ptr %_0, align 1, !dbg !490
+ br label %bb4, !dbg !490
+
+panic: ; preds = %bb1
+; call core::panicking::panic_const::panic_const_sub_overflow
+ call void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8 @alloc_911aa589553e6649ae5da752650f3354) #7, !dbg !488
+ unreachable, !dbg !488
+}
+
+; tail_call_test::main
+; Function Attrs: uwtable
+define internal void @_ZN14tail_call_test4main17h34b192e87b023961E() unnamed_addr #0 !dbg !491 {
+start:
+ %_22 = alloca [16 x i8], align 8
+ %_20 = alloca [16 x i8], align 8
+ %_18 = alloca [16 x i8], align 8
+ %_16 = alloca [16 x i8], align 8
+ %_14 = alloca [16 x i8], align 8
+ %_12 = alloca [16 x i8], align 8
+ %_11 = alloca [96 x i8], align 8
+ %_8 = alloca [48 x i8], align 8
+ %odd_no_tail_result = alloca [1 x i8], align 1
+ %even_no_tail_result = alloca [1 x i8], align 1
+ %odd_with_tail_result = alloca [1 x i8], align 1
+ %even_with_tail_result = alloca [1 x i8], align 1
+ %no_tail_result = alloca [4 x i8], align 4
+ %with_tail_result = alloca [4 x i8], align 4
+ #dbg_declare(ptr %with_tail_result, !493, !DIExpression(), !505)
+ #dbg_declare(ptr %no_tail_result, !495, !DIExpression(), !506)
+ #dbg_declare(ptr %even_with_tail_result, !497, !DIExpression(), !507)
+ #dbg_declare(ptr %odd_with_tail_result, !499, !DIExpression(), !508)
+ #dbg_declare(ptr %even_no_tail_result, !501, !DIExpression(), !509)
+ #dbg_declare(ptr %odd_no_tail_result, !503, !DIExpression(), !510)
+; call tail_call_test::with_tail
+ %0 = call i32 @_ZN14tail_call_test9with_tail17hc3aece45eddbb180E(i32 5), !dbg !511
+ store i32 %0, ptr %with_tail_result, align 4, !dbg !511
+; call tail_call_test::no_tail
+ %1 = call i32 @_ZN14tail_call_test7no_tail17h8d6adcb9d9b56776E(i32 5), !dbg !512
+ store i32 %1, ptr %no_tail_result, align 4, !dbg !512
+; call tail_call_test::even_with_tail
+ %2 = call zeroext i1 @_ZN14tail_call_test14even_with_tail17h8d1dbeb6515757cfE(i32 10), !dbg !513
+ %3 = zext i1 %2 to i8, !dbg !513
+ store i8 %3, ptr %even_with_tail_result, align 1, !dbg !513
+; call tail_call_test::odd_with_tail
+ %4 = call zeroext i1 @_ZN14tail_call_test13odd_with_tail17hc95516150aaddcc1E(i32 10), !dbg !514
+ %5 = zext i1 %4 to i8, !dbg !514
+ store i8 %5, ptr %odd_with_tail_result, align 1, !dbg !514
+; call tail_call_test::even_no_tail
+ %6 = call zeroext i1 @_ZN14tail_call_test12even_no_tail17hd3be8e5729868b97E(i32 10), !dbg !515
+ %7 = zext i1 %6 to i8, !dbg !515
+ store i8 %7, ptr %even_no_tail_result, align 1, !dbg !515
+; call tail_call_test::odd_no_tail
+ %8 = call zeroext i1 @_ZN14tail_call_test11odd_no_tail17h1399b4ae4de50274E(i32 10), !dbg !516
+ %9 = zext i1 %8 to i8, !dbg !516
+ store i8 %9, ptr %odd_no_tail_result, align 1, !dbg !516
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17ha8da45a5453b2abdE(ptr sret([16 x i8]) align 8 %_12, ptr align 4 %with_tail_result), !dbg !517
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17ha8da45a5453b2abdE(ptr sret([16 x i8]) align 8 %_14, ptr align 4 %no_tail_result), !dbg !517
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE(ptr sret([16 x i8]) align 8 %_16, ptr align 1 %even_with_tail_result), !dbg !517
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE(ptr sret([16 x i8]) align 8 %_18, ptr align 1 %odd_with_tail_result), !dbg !517
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE(ptr sret([16 x i8]) align 8 %_20, ptr align 1 %even_no_tail_result), !dbg !517
+; call core::fmt::rt::Argument::new_display
+ call void @_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE(ptr sret([16 x i8]) align 8 %_22, ptr align 1 %odd_no_tail_result), !dbg !517
+ %10 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 0, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %10, ptr align 8 %_12, i64 16, i1 false), !dbg !517
+ %11 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 1, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %11, ptr align 8 %_14, i64 16, i1 false), !dbg !517
+ %12 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 2, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %12, ptr align 8 %_16, i64 16, i1 false), !dbg !517
+ %13 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 3, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %13, ptr align 8 %_18, i64 16, i1 false), !dbg !517
+ %14 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 4, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %14, ptr align 8 %_20, i64 16, i1 false), !dbg !517
+ %15 = getelementptr inbounds nuw %"core::fmt::rt::Argument<'_>", ptr %_11, i64 5, !dbg !517
+ call void @llvm.memcpy.p0.p0.i64(ptr align 8 %15, ptr align 8 %_22, i64 16, i1 false), !dbg !517
+; call core::fmt::Arguments::new_v1
+ call void @_ZN4core3fmt9Arguments6new_v117h7b06876a57e3281cE(ptr sret([48 x i8]) align 8 %_8, ptr align 8 @alloc_70b8f01ca3944289d1c53010fd7cc68a, ptr align 8 %_11), !dbg !517
+; call std::io::stdio::_print
+ call void @_ZN3std2io5stdio6_print17h976fe03d511b8afaE(ptr align 8 %_8), !dbg !517
+ ret void, !dbg !518
+}
+
+; std::rt::lang_start_internal
+; Function Attrs: uwtable
+declare i64 @_ZN3std2rt19lang_start_internal17hff478237ff51a9c7E(ptr align 1, ptr align 8, i64, ptr, i8) unnamed_addr #0
+
+; <bool as core::fmt::Display>::fmt
+; Function Attrs: uwtable
+declare zeroext i1 @"_ZN43_$LT$bool$u20$as$u20$core..fmt..Display$GT$3fmt17hd249e77bcd60ee87E"(ptr align 1, ptr align 8) unnamed_addr #0
+
+; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg) #3
+
+; core::fmt::num::imp::<impl core::fmt::Display for u32>::fmt
+; Function Attrs: uwtable
+declare zeroext i1 @"_ZN4core3fmt3num3imp52_$LT$impl$u20$core..fmt..Display$u20$for$u20$u32$GT$3fmt17h2d6296303bc86543E"(ptr align 4, ptr align 8) unnamed_addr #0
+
+; Function Attrs: nounwind uwtable
+declare i32 @rust_eh_personality(i32, i32, i64, ptr, ptr) unnamed_addr #4
+
+; core::panicking::panic_const::panic_const_sub_overflow
+; Function Attrs: cold noinline noreturn uwtable
+declare void @_ZN4core9panicking11panic_const24panic_const_sub_overflow17h3d6828dc280c05eeE(ptr align 8) unnamed_addr #5
+
+; std::io::stdio::_print
+; Function Attrs: uwtable
+declare void @_ZN3std2io5stdio6_print17h976fe03d511b8afaE(ptr align 8) unnamed_addr #0
+
+define i32 @main(i32 %0, ptr %1) unnamed_addr #6 {
+top:
+ %2 = sext i32 %0 to i64
+; call std::rt::lang_start
+ %3 = call i64 @_ZN3std2rt10lang_start17h73b0c5d8223deb96E(ptr @_ZN14tail_call_test4main17h34b192e87b023961E, i64 %2, ptr %1, i8 0)
+ %4 = trunc i64 %3 to i32
+ ret i32 %4
+}
+
+attributes #0 = { uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" }
+attributes #1 = { inlinehint uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" }
+attributes #2 = { noinline uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" }
+attributes #3 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+attributes #4 = { nounwind uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" }
+attributes #5 = { cold noinline noreturn uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" }
+attributes #6 = { "frame-pointer"="non-leaf" "target-cpu"="apple-m1" }
+attributes #7 = { noreturn }
+
+!llvm.module.flags = !{!24, !25, !26, !27}
+!llvm.ident = !{!28}
+!llvm.dbg.cu = !{!29}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "<std::rt::lang_start::{closure_env#0}<()> as core::ops::function::Fn<()>>::{vtable}", scope: null, file: !2, type: !3, isLocal: true, isDefinition: true)
+!2 = !DIFile(filename: "<unknown>", directory: "")
+!3 = !DICompositeType(tag: DW_TAG_structure_type, name: "<std::rt::lang_start::{closure_env#0}<()> as core::ops::function::Fn<()>>::{vtable_type}", file: !2, size: 384, align: 64, flags: DIFlagArtificial, elements: !4, vtableHolder: !14, templateParams: !23, identifier: "2f8c94bd20c0aded7d0943cfe7a062da")
+!4 = !{!5, !8, !10, !11, !12, !13}
+!5 = !DIDerivedType(tag: DW_TAG_member, name: "drop_in_place", scope: !3, file: !2, baseType: !6, size: 64, align: 64)
+!6 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const ()", baseType: !7, size: 64, align: 64, dwarfAddressSpace: 0)
+!7 = !DIBasicType(name: "()", encoding: DW_ATE_unsigned)
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "size", scope: !3, file: !2, baseType: !9, size: 64, align: 64, offset: 64)
+!9 = !DIBasicType(name: "usize", size: 64, encoding: DW_ATE_unsigned)
+!10 = !DIDerivedType(tag: DW_TAG_member, name: "align", scope: !3, file: !2, baseType: !9, size: 64, align: 64, offset: 128)
+!11 = !DIDerivedType(tag: DW_TAG_member, name: "__method3", scope: !3, file: !2, baseType: !6, size: 64, align: 64, offset: 192)
+!12 = !DIDerivedType(tag: DW_TAG_member, name: "__method4", scope: !3, file: !2, baseType: !6, size: 64, align: 64, offset: 256)
+!13 = !DIDerivedType(tag: DW_TAG_member, name: "__method5", scope: !3, file: !2, baseType: !6, size: 64, align: 64, offset: 320)
+!14 = !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}<()>", scope: !15, file: !2, size: 64, align: 64, elements: !18, templateParams: !23, identifier: "a4895dfcea3453f6cd237ae6cb71c022")
+!15 = !DINamespace(name: "lang_start", scope: !16)
+!16 = !DINamespace(name: "rt", scope: !17)
+!17 = !DINamespace(name: "std", scope: null)
+!18 = !{!19}
+!19 = !DIDerivedType(tag: DW_TAG_member, name: "main", scope: !14, file: !2, baseType: !20, size: 64, align: 64)
+!20 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "fn()", baseType: !21, size: 64, align: 64, dwarfAddressSpace: 0)
+!21 = !DISubroutineType(types: !22)
+!22 = !{null}
+!23 = !{}
+!24 = !{i32 8, !"PIC Level", i32 2}
+!25 = !{i32 7, !"PIE Level", i32 2}
+!26 = !{i32 7, !"Dwarf Version", i32 4}
+!27 = !{i32 2, !"Debug Info Version", i32 3}
+!28 = !{!"rustc version 1.87.0-dev"}
+!29 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !30, producer: "clang LLVM (rustc version 1.87.0-dev)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !31, globals: !44, splitDebugInlining: false, nameTableKind: None)
+!30 = !DIFile(filename: "tail-call-test.rs/@/tail_call_test.7c02b6d4e63aa8f0-cgu.0", directory: "/Users/mhornicky/rust/tests/run-make/tail-call-llvm-ir")
+!31 = !{!32, !40}
+!32 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "Alignment", scope: !33, file: !2, baseType: !35, size: 8, align: 8, flags: DIFlagEnumClass, elements: !36)
+!33 = !DINamespace(name: "fmt", scope: !34)
+!34 = !DINamespace(name: "core", scope: null)
+!35 = !DIBasicType(name: "u8", size: 8, encoding: DW_ATE_unsigned)
+!36 = !{!37, !38, !39}
+!37 = !DIEnumerator(name: "Left", value: 0, isUnsigned: true)
+!38 = !DIEnumerator(name: "Right", value: 1, isUnsigned: true)
+!39 = !DIEnumerator(name: "Center", value: 2, isUnsigned: true)
+!40 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "Alignment", scope: !41, file: !2, baseType: !35, size: 8, align: 8, flags: DIFlagEnumClass, elements: !42)
+!41 = !DINamespace(name: "rt", scope: !33)
+!42 = !{!37, !38, !39, !43}
+!43 = !DIEnumerator(name: "Unknown", value: 3, isUnsigned: true)
+!44 = !{!0}
+!45 = distinct !DISubprogram(name: "lang_start<()>", linkageName: "_ZN3std2rt10lang_start17h73b0c5d8223deb96E", scope: !16, file: !46, line: 192, type: !47, scopeLine: 192, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !57, retainedNodes: !52)
+!46 = !DIFile(filename: "/Users/mhornicky/rust/library/std/src/rt.rs", directory: "", checksumkind: CSK_MD5, checksum: "5ed61ab28987f8860d5842313c6741b3")
+!47 = !DISubroutineType(types: !48)
+!48 = !{!49, !20, !49, !50, !35}
+!49 = !DIBasicType(name: "isize", size: 64, encoding: DW_ATE_signed)
+!50 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const *const u8", baseType: !51, size: 64, align: 64, dwarfAddressSpace: 0)
+!51 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const u8", baseType: !35, size: 64, align: 64, dwarfAddressSpace: 0)
+!52 = !{!53, !54, !55, !56}
+!53 = !DILocalVariable(name: "main", arg: 1, scope: !45, file: !46, line: 193, type: !20)
+!54 = !DILocalVariable(name: "argc", arg: 2, scope: !45, file: !46, line: 194, type: !49)
+!55 = !DILocalVariable(name: "argv", arg: 3, scope: !45, file: !46, line: 195, type: !50)
+!56 = !DILocalVariable(name: "sigpipe", arg: 4, scope: !45, file: !46, line: 196, type: !35)
+!57 = !{!58}
+!58 = !DITemplateTypeParameter(name: "T", type: !7)
+!59 = !DILocation(line: 193, column: 5, scope: !45)
+!60 = !DILocation(line: 194, column: 5, scope: !45)
+!61 = !DILocation(line: 195, column: 5, scope: !45)
+!62 = !DILocation(line: 196, column: 5, scope: !45)
+!63 = !DILocation(line: 199, column: 10, scope: !45)
+!64 = !DILocation(line: 198, column: 5, scope: !45)
+!65 = !DILocation(line: 204, column: 2, scope: !45)
+!66 = distinct !DISubprogram(name: "{closure#0}<()>", linkageName: "_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h9631b88370906e50E", scope: !15, file: !46, line: 199, type: !67, scopeLine: 199, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !57, retainedNodes: !71)
+!67 = !DISubroutineType(types: !68)
+!68 = !{!69, !70}
+!69 = !DIBasicType(name: "i32", size: 32, encoding: DW_ATE_signed)
+!70 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&std::rt::lang_start::{closure_env#0}<()>", baseType: !14, size: 64, align: 64, dwarfAddressSpace: 0)
+!71 = !{!72}
+!72 = !DILocalVariable(name: "main", scope: !66, file: !46, line: 193, type: !20, align: 64)
+!73 = !DILocation(line: 193, column: 5, scope: !66)
+!74 = !DILocation(line: 199, column: 70, scope: !66)
+!75 = !DILocation(line: 199, column: 18, scope: !66)
+!76 = !DILocalVariable(name: "self", arg: 1, scope: !77, file: !78, line: 2062, type: !79)
+!77 = distinct !DISubprogram(name: "to_i32", linkageName: "_ZN3std7process8ExitCode6to_i3217h2aa505e63ed55e56E", scope: !79, file: !78, line: 2062, type: !91, scopeLine: 2062, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, declaration: !93, retainedNodes: !94)
+!78 = !DIFile(filename: "/Users/mhornicky/rust/library/std/src/process.rs", directory: "", checksumkind: CSK_MD5, checksum: "dbc7956c9cbb5ca52b3803dc48bc1d09")
+!79 = !DICompositeType(tag: DW_TAG_structure_type, name: "ExitCode", scope: !80, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !81, templateParams: !23, identifier: "72dea078999b9e93868f7a94d355d67a")
+!80 = !DINamespace(name: "process", scope: !17)
+!81 = !{!82}
+!82 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !79, file: !2, baseType: !83, size: 8, align: 8, flags: DIFlagPrivate)
+!83 = !DICompositeType(tag: DW_TAG_structure_type, name: "ExitCode", scope: !84, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !89, templateParams: !23, identifier: "4f89cd34e9814efc996e2d1833a5a873")
+!84 = !DINamespace(name: "process_common", scope: !85)
+!85 = !DINamespace(name: "process", scope: !86)
+!86 = !DINamespace(name: "unix", scope: !87)
+!87 = !DINamespace(name: "pal", scope: !88)
+!88 = !DINamespace(name: "sys", scope: !17)
+!89 = !{!90}
+!90 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !83, file: !2, baseType: !35, size: 8, align: 8, flags: DIFlagPrivate)
+!91 = !DISubroutineType(types: !92)
+!92 = !{!69, !79}
+!93 = !DISubprogram(name: "to_i32", linkageName: "_ZN3std7process8ExitCode6to_i3217h2aa505e63ed55e56E", scope: !79, file: !78, line: 2062, type: !91, scopeLine: 2062, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit, templateParams: !23)
+!94 = !{!76}
+!95 = !DILocation(line: 2062, column: 19, scope: !77, inlinedAt: !96)
+!96 = !DILocation(line: 199, column: 85, scope: !66)
+!97 = !DILocation(line: 631, column: 9, scope: !98, inlinedAt: !104)
+!98 = distinct !DISubprogram(name: "as_i32", linkageName: "_ZN3std3sys3pal4unix7process14process_common8ExitCode6as_i3217h7fe5ef8d5d6ab3beE", scope: !83, file: !99, line: 630, type: !100, scopeLine: 630, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, declaration: !103)
+!99 = !DIFile(filename: "/Users/mhornicky/rust/library/std/src/sys/pal/unix/process/process_common.rs", directory: "", checksumkind: CSK_MD5, checksum: "53377008eaa564ea7afaa2596ee97e68")
+!100 = !DISubroutineType(types: !101)
+!101 = !{!69, !102}
+!102 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&std::sys::pal::unix::process::process_common::ExitCode", baseType: !83, size: 64, align: 64, dwarfAddressSpace: 0)
+!103 = !DISubprogram(name: "as_i32", linkageName: "_ZN3std3sys3pal4unix7process14process_common8ExitCode6as_i3217h7fe5ef8d5d6ab3beE", scope: !83, file: !99, line: 630, type: !100, scopeLine: 630, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit, templateParams: !23)
+!104 = !DILocation(line: 2063, column: 16, scope: !77, inlinedAt: !96)
+!105 = !DILocation(line: 199, column: 93, scope: !66)
+!106 = distinct !DISubprogram(name: "__rust_begin_short_backtrace<fn(), ()>", linkageName: "_ZN3std3sys9backtrace28__rust_begin_short_backtrace17hac99c3a0f565fd14E", scope: !108, file: !107, line: 148, type: !109, scopeLine: 148, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !115, retainedNodes: !111)
+!107 = !DIFile(filename: "/Users/mhornicky/rust/library/std/src/sys/backtrace.rs", directory: "", checksumkind: CSK_MD5, checksum: "9e30c70624c3cf40238860e740bd696f")
+!108 = !DINamespace(name: "backtrace", scope: !88)
+!109 = !DISubroutineType(types: !110)
+!110 = !{null, !20}
+!111 = !{!112, !113}
+!112 = !DILocalVariable(name: "f", arg: 1, scope: !106, file: !107, line: 148, type: !20)
+!113 = !DILocalVariable(name: "result", scope: !114, file: !107, line: 152, type: !7, align: 8)
+!114 = distinct !DILexicalBlock(scope: !106, file: !107, line: 152, column: 5)
+!115 = !{!116, !58}
+!116 = !DITemplateTypeParameter(name: "F", type: !20)
+!117 = !DILocation(line: 152, column: 9, scope: !114)
+!118 = !DILocation(line: 148, column: 43, scope: !106)
+!119 = !DILocalVariable(name: "dummy", scope: !120, file: !121, line: 476, type: !7, align: 8)
+!120 = distinct !DISubprogram(name: "black_box<()>", linkageName: "_ZN4core4hint9black_box17h8534f6bf278d4519E", scope: !122, file: !121, line: 476, type: !123, scopeLine: 476, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !57, retainedNodes: !125)
+!121 = !DIFile(filename: "/Users/mhornicky/rust/library/core/src/hint.rs", directory: "", checksumkind: CSK_MD5, checksum: "53e417654697d2a6fdb3b165cec3a4bf")
+!122 = !DINamespace(name: "hint", scope: !34)
+!123 = !DISubroutineType(types: !124)
+!124 = !{null, !7}
+!125 = !{!119}
+!126 = !DILocation(line: 476, column: 27, scope: !120, inlinedAt: !127)
+!127 = !DILocation(line: 155, column: 5, scope: !114)
+!128 = !DILocation(line: 152, column: 18, scope: !106)
+!129 = !DILocation(line: 477, column: 5, scope: !120, inlinedAt: !127)
+!130 = !{i64 8485502464173410}
+!131 = !DILocation(line: 158, column: 2, scope: !106)
+!132 = distinct !DISubprogram(name: "new_display<bool>", linkageName: "_ZN4core3fmt2rt8Argument11new_display17h4175f487a240089cE", scope: !134, file: !133, line: 117, type: !235, scopeLine: 117, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !240, declaration: !239, retainedNodes: !242)
+!133 = !DIFile(filename: "/Users/mhornicky/rust/library/core/src/fmt/rt.rs", directory: "", checksumkind: CSK_MD5, checksum: "d6ea0cb069b4dd82e2f5159937043044")
+!134 = !DICompositeType(tag: DW_TAG_structure_type, name: "Argument", scope: !41, file: !2, size: 128, align: 64, flags: DIFlagPublic, elements: !135, templateParams: !23, identifier: "58602aa2c593cb801ff091631542096c")
+!135 = !{!136}
+!136 = !DIDerivedType(tag: DW_TAG_member, name: "ty", scope: !134, file: !2, baseType: !137, size: 128, align: 64, flags: DIFlagPrivate)
+!137 = !DICompositeType(tag: DW_TAG_structure_type, name: "ArgumentType", scope: !41, file: !2, size: 128, align: 64, flags: DIFlagPrivate, elements: !138, templateParams: !23, identifier: "dd627857a0a4b5126a3e76cda7e5e252")
+!138 = !{!139}
+!139 = !DICompositeType(tag: DW_TAG_variant_part, scope: !137, file: !2, size: 128, align: 64, elements: !140, templateParams: !23, identifier: "6c932759f42856361ff813d4bc4a8f25", discriminator: !233)
+!140 = !{!141, !229}
+!141 = !DIDerivedType(tag: DW_TAG_member, name: "Placeholder", scope: !139, file: !2, baseType: !142, size: 128, align: 64)
+!142 = !DICompositeType(tag: DW_TAG_structure_type, name: "Placeholder", scope: !137, file: !2, size: 128, align: 64, flags: DIFlagPrivate, elements: !143, templateParams: !23, identifier: "80dee0a6bd69ed65c77b53727d80f07")
+!143 = !{!144, !150, !223}
+!144 = !DIDerivedType(tag: DW_TAG_member, name: "value", scope: !142, file: !2, baseType: !145, size: 64, align: 64, flags: DIFlagPrivate)
+!145 = !DICompositeType(tag: DW_TAG_structure_type, name: "NonNull<()>", scope: !146, file: !2, size: 64, align: 64, flags: DIFlagPublic, elements: !148, templateParams: !57, identifier: "522b50db7ed759a870943796bd4bf4ef")
+!146 = !DINamespace(name: "non_null", scope: !147)
+!147 = !DINamespace(name: "ptr", scope: !34)
+!148 = !{!149}
+!149 = !DIDerivedType(tag: DW_TAG_member, name: "pointer", scope: !145, file: !2, baseType: !6, size: 64, align: 64, flags: DIFlagPrivate)
+!150 = !DIDerivedType(tag: DW_TAG_member, name: "formatter", scope: !142, file: !2, baseType: !151, size: 64, align: 64, offset: 64, flags: DIFlagPrivate)
+!151 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "unsafe fn(core::ptr::non_null::NonNull<()>, &mut core::fmt::Formatter) -> core::result::Result<(), core::fmt::Error>", baseType: !152, size: 64, align: 64, dwarfAddressSpace: 0)
+!152 = !DISubroutineType(types: !153)
+!153 = !{!154, !145, !171}
+!154 = !DICompositeType(tag: DW_TAG_structure_type, name: "Result<(), core::fmt::Error>", scope: !155, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !156, templateParams: !23, identifier: "17271d3ec660ce12aee8618532c0d01b")
+!155 = !DINamespace(name: "result", scope: !34)
+!156 = !{!157}
+!157 = !DICompositeType(tag: DW_TAG_variant_part, scope: !154, file: !2, size: 8, align: 8, elements: !158, templateParams: !23, identifier: "9cad8f3040adeb8dbe6012f7f86f4bd0", discriminator: !170)
+!158 = !{!159, !166}
+!159 = !DIDerivedType(tag: DW_TAG_member, name: "Ok", scope: !157, file: !2, baseType: !160, size: 8, align: 8, extraData: i8 0)
+!160 = !DICompositeType(tag: DW_TAG_structure_type, name: "Ok", scope: !154, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !161, templateParams: !163, identifier: "a37c316bb402f538ae3e417e84a747f2")
+!161 = !{!162}
+!162 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !160, file: !2, baseType: !7, align: 8, offset: 8, flags: DIFlagPublic)
+!163 = !{!58, !164}
+!164 = !DITemplateTypeParameter(name: "E", type: !165)
+!165 = !DICompositeType(tag: DW_TAG_structure_type, name: "Error", scope: !33, file: !2, align: 8, flags: DIFlagPublic, elements: !23, identifier: "ee06b97bde4a910016d9c46d09308354")
+!166 = !DIDerivedType(tag: DW_TAG_member, name: "Err", scope: !157, file: !2, baseType: !167, size: 8, align: 8, extraData: i8 1)
+!167 = !DICompositeType(tag: DW_TAG_structure_type, name: "Err", scope: !154, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !168, templateParams: !163, identifier: "843870027c42a051bd66e4e2437dcb2c")
+!168 = !{!169}
+!169 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !167, file: !2, baseType: !165, align: 8, offset: 8, flags: DIFlagPublic)
+!170 = !DIDerivedType(tag: DW_TAG_member, scope: !154, file: !2, baseType: !35, size: 8, align: 8, flags: DIFlagArtificial)
+!171 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&mut core::fmt::Formatter", baseType: !172, size: 64, align: 64, dwarfAddressSpace: 0)
+!172 = !DICompositeType(tag: DW_TAG_structure_type, name: "Formatter", scope: !33, file: !2, size: 320, align: 64, flags: DIFlagPublic, elements: !173, templateParams: !23, identifier: "a3f681b15854bb9231b344542d7ebc6f")
+!173 = !{!174, !212}
+!174 = !DIDerivedType(tag: DW_TAG_member, name: "options", scope: !172, file: !2, baseType: !175, size: 160, align: 32, offset: 128, flags: DIFlagPrivate)
+!175 = !DICompositeType(tag: DW_TAG_structure_type, name: "FormattingOptions", scope: !33, file: !2, size: 160, align: 32, flags: DIFlagPublic, elements: !176, templateParams: !23, identifier: "bd4dc7dc318efc33da8742bbcae2b323")
+!176 = !{!177, !179, !181, !196, !211}
+!177 = !DIDerivedType(tag: DW_TAG_member, name: "flags", scope: !175, file: !2, baseType: !178, size: 32, align: 32, offset: 96, flags: DIFlagPrivate)
+!178 = !DIBasicType(name: "u32", size: 32, encoding: DW_ATE_unsigned)
+!179 = !DIDerivedType(tag: DW_TAG_member, name: "fill", scope: !175, file: !2, baseType: !180, size: 32, align: 32, flags: DIFlagPrivate)
+!180 = !DIBasicType(name: "char", size: 32, encoding: DW_ATE_UTF)
+!181 = !DIDerivedType(tag: DW_TAG_member, name: "align", scope: !175, file: !2, baseType: !182, size: 8, align: 8, offset: 128, flags: DIFlagPrivate)
+!182 = !DICompositeType(tag: DW_TAG_structure_type, name: "Option<core::fmt::Alignment>", scope: !183, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !184, templateParams: !23, identifier: "64192f2e10752a36e12c723698eef876")
+!183 = !DINamespace(name: "option", scope: !34)
+!184 = !{!185}
+!185 = !DICompositeType(tag: DW_TAG_variant_part, scope: !182, file: !2, size: 8, align: 8, elements: !186, templateParams: !23, identifier: "d880d00e6d747b0f1f6e8a9e94eaf5c3", discriminator: !195)
+!186 = !{!187, !191}
+!187 = !DIDerivedType(tag: DW_TAG_member, name: "None", scope: !185, file: !2, baseType: !188, size: 8, align: 8, extraData: i8 3)
+!188 = !DICompositeType(tag: DW_TAG_structure_type, name: "None", scope: !182, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !23, templateParams: !189, identifier: "3d08e22b372bde88294a2316f9f57841")
+!189 = !{!190}
+!190 = !DITemplateTypeParameter(name: "T", type: !32)
+!191 = !DIDerivedType(tag: DW_TAG_member, name: "Some", scope: !185, file: !2, baseType: !192, size: 8, align: 8)
+!192 = !DICompositeType(tag: DW_TAG_structure_type, name: "Some", scope: !182, file: !2, size: 8, align: 8, flags: DIFlagPublic, elements: !193, templateParams: !189, identifier: "3a9e5713ecba1e91a97a517dafcb7ac3")
+!193 = !{!194}
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+!362 = !{!363}
+!363 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !361, file: !2, baseType: !332, size: 128, align: 64, flags: DIFlagPublic)
+!364 = !DIDerivedType(tag: DW_TAG_member, scope: !324, file: !2, baseType: !234, size: 64, align: 64, flags: DIFlagArtificial)
+!365 = !DIDerivedType(tag: DW_TAG_member, name: "args", scope: !310, file: !2, baseType: !366, size: 128, align: 64, offset: 128, flags: DIFlagPrivate)
+!366 = !DICompositeType(tag: DW_TAG_structure_type, name: "&[core::fmt::rt::Argument]", file: !2, size: 128, align: 64, elements: !367, templateParams: !23, identifier: "3e1f378cdfe395f4956f75b2ec174ba6")
+!367 = !{!368, !370}
+!368 = !DIDerivedType(tag: DW_TAG_member, name: "data_ptr", scope: !366, file: !2, baseType: !369, size: 64, align: 64)
+!369 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !134, size: 64, align: 64, dwarfAddressSpace: 0)
+!370 = !DIDerivedType(tag: DW_TAG_member, name: "length", scope: !366, file: !2, baseType: !9, size: 64, align: 64, offset: 64)
+!371 = !DISubroutineType(types: !372)
+!372 = !{!310, !373, !377}
+!373 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&[&str; 7]", baseType: !374, size: 64, align: 64, dwarfAddressSpace: 0)
+!374 = !DICompositeType(tag: DW_TAG_array_type, baseType: !317, size: 896, align: 64, elements: !375)
+!375 = !{!376}
+!376 = !DISubrange(count: 7, lowerBound: 0)
+!377 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&[core::fmt::rt::Argument; 6]", baseType: !378, size: 64, align: 64, dwarfAddressSpace: 0)
+!378 = !DICompositeType(tag: DW_TAG_array_type, baseType: !134, size: 768, align: 64, elements: !221)
+!379 = !DISubprogram(name: "new_v1<7, 6>", linkageName: "_ZN4core3fmt9Arguments6new_v117h7b06876a57e3281cE", scope: !310, file: !309, line: 608, type: !371, scopeLine: 608, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit, templateParams: !23)
+!380 = !{!381, !382}
+!381 = !DILocalVariable(name: "pieces", arg: 1, scope: !308, file: !309, line: 609, type: !373)
+!382 = !DILocalVariable(name: "args", arg: 2, scope: !308, file: !309, line: 610, type: !377)
+!383 = !DILocation(line: 609, column: 9, scope: !308)
+!384 = !DILocation(line: 610, column: 9, scope: !308)
+!385 = !DILocation(line: 613, column: 9, scope: !308)
+!386 = !DILocation(line: 614, column: 6, scope: !308)
+!387 = distinct !DISubprogram(name: "call_once<std::rt::lang_start::{closure_env#0}<()>, ()>", linkageName: "_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17h4fa86179f7747905E", scope: !389, file: !388, line: 250, type: !392, scopeLine: 250, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !398, retainedNodes: !395)
+!388 = !DIFile(filename: "/Users/mhornicky/rust/library/core/src/ops/function.rs", directory: "", checksumkind: CSK_MD5, checksum: "27f40bbdeb6cc525c0d0d7cf434d92c4")
+!389 = !DINamespace(name: "FnOnce", scope: !390)
+!390 = !DINamespace(name: "function", scope: !391)
+!391 = !DINamespace(name: "ops", scope: !34)
+!392 = !DISubroutineType(types: !393)
+!393 = !{!69, !394}
+!394 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*mut std::rt::lang_start::{closure_env#0}<()>", baseType: !14, size: 64, align: 64, dwarfAddressSpace: 0)
+!395 = !{!396, !397}
+!396 = !DILocalVariable(arg: 1, scope: !387, file: !388, line: 250, type: !394)
+!397 = !DILocalVariable(arg: 2, scope: !387, file: !388, line: 250, type: !7)
+!398 = !{!399, !400}
+!399 = !DITemplateTypeParameter(name: "Self", type: !14)
+!400 = !DITemplateTypeParameter(name: "Args", type: !7)
+!401 = !DILocation(line: 250, column: 5, scope: !387)
+!402 = distinct !DISubprogram(name: "call_once<std::rt::lang_start::{closure_env#0}<()>, ()>", linkageName: "_ZN4core3ops8function6FnOnce9call_once17ha95bcc209a0f6c7cE", scope: !389, file: !388, line: 250, type: !403, scopeLine: 250, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !398, retainedNodes: !405)
+!403 = !DISubroutineType(types: !404)
+!404 = !{!69, !14}
+!405 = !{!406, !407}
+!406 = !DILocalVariable(arg: 1, scope: !402, file: !388, line: 250, type: !14)
+!407 = !DILocalVariable(arg: 2, scope: !402, file: !388, line: 250, type: !7)
+!408 = !DILocation(line: 250, column: 5, scope: !402)
+!409 = distinct !DISubprogram(name: "call_once<fn(), ()>", linkageName: "_ZN4core3ops8function6FnOnce9call_once17hfd4f30177a814130E", scope: !389, file: !388, line: 250, type: !109, scopeLine: 250, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !413, retainedNodes: !410)
+!410 = !{!411, !412}
+!411 = !DILocalVariable(arg: 1, scope: !409, file: !388, line: 250, type: !20)
+!412 = !DILocalVariable(arg: 2, scope: !409, file: !388, line: 250, type: !7)
+!413 = !{!414, !400}
+!414 = !DITemplateTypeParameter(name: "Self", type: !20)
+!415 = !DILocation(line: 250, column: 5, scope: !409)
+!416 = distinct !DISubprogram(name: "drop_in_place<std::rt::lang_start::{closure_env#0}<()>>", linkageName: "_ZN4core3ptr85drop_in_place$LT$std..rt..lang_start$LT$$LP$$RP$$GT$..$u7b$$u7b$closure$u7d$$u7d$$GT$17h2dc5dcfe3d451b5dE", scope: !147, file: !417, line: 523, type: !418, scopeLine: 523, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !422, retainedNodes: !420)
+!417 = !DIFile(filename: "/Users/mhornicky/rust/library/core/src/ptr/mod.rs", directory: "", checksumkind: CSK_MD5, checksum: "a5cb8c8d2ea510166b9e600d925000e6")
+!418 = !DISubroutineType(types: !419)
+!419 = !{null, !394}
+!420 = !{!421}
+!421 = !DILocalVariable(arg: 1, scope: !416, file: !417, line: 523, type: !394)
+!422 = !{!423}
+!423 = !DITemplateTypeParameter(name: "T", type: !14)
+!424 = !DILocation(line: 523, column: 1, scope: !416)
+!425 = distinct !DISubprogram(name: "report", linkageName: "_ZN54_$LT$$LP$$RP$$u20$as$u20$std..process..Termination$GT$6report17hccf942a05a23072aE", scope: !426, file: !78, line: 2432, type: !427, scopeLine: 2432, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !429)
+!426 = !DINamespace(name: "{impl#57}", scope: !80)
+!427 = !DISubroutineType(types: !428)
+!428 = !{!79, !7}
+!429 = !{!430}
+!430 = !DILocalVariable(arg: 1, scope: !425, file: !78, line: 2432, type: !7)
+!431 = !DILocation(line: 2432, column: 15, scope: !425)
+!432 = !DILocation(line: 2434, column: 6, scope: !425)
+!433 = distinct !DISubprogram(name: "with_tail", linkageName: "_ZN14tail_call_test9with_tail17hc3aece45eddbb180E", scope: !435, file: !434, line: 5, type: !436, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !438)
+!434 = !DIFile(filename: "tail-call-test.rs", directory: "/Users/mhornicky/rust/tests/run-make/tail-call-llvm-ir", checksumkind: CSK_MD5, checksum: "c9d420132c078a5cd245c6d5c9374767")
+!435 = !DINamespace(name: "tail_call_test", scope: null)
+!436 = !DISubroutineType(types: !437)
+!437 = !{!178, !178}
+!438 = !{!439}
+!439 = !DILocalVariable(name: "n", arg: 1, scope: !433, file: !434, line: 5, type: !178)
+!440 = !DILocation(line: 5, column: 18, scope: !433)
+!441 = !DILocation(line: 6, column: 8, scope: !433)
+!442 = !DILocation(line: 11, column: 2, scope: !433)
+!443 = !DILocation(line: 9, column: 26, scope: !433)
+!444 = !DILocation(line: 9, column: 9, scope: !433)
+!445 = distinct !DISubprogram(name: "no_tail", linkageName: "_ZN14tail_call_test7no_tail17h8d6adcb9d9b56776E", scope: !435, file: !434, line: 15, type: !436, scopeLine: 15, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !446)
+!446 = !{!447}
+!447 = !DILocalVariable(name: "n", arg: 1, scope: !445, file: !434, line: 15, type: !178)
+!448 = !DILocation(line: 15, column: 16, scope: !445)
+!449 = !DILocation(line: 16, column: 8, scope: !445)
+!450 = !DILocation(line: 17, column: 9, scope: !445)
+!451 = !DILocation(line: 16, column: 5, scope: !445)
+!452 = !DILocation(line: 19, column: 17, scope: !445)
+!453 = !DILocation(line: 21, column: 2, scope: !445)
+!454 = !DILocation(line: 19, column: 9, scope: !445)
+!455 = distinct !DISubprogram(name: "even_with_tail", linkageName: "_ZN14tail_call_test14even_with_tail17h8d1dbeb6515757cfE", scope: !435, file: !434, line: 25, type: !456, scopeLine: 25, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !458)
+!456 = !DISubroutineType(types: !457)
+!457 = !{!238, !178}
+!458 = !{!459}
+!459 = !DILocalVariable(name: "n", arg: 1, scope: !455, file: !434, line: 25, type: !178)
+!460 = !DILocation(line: 25, column: 23, scope: !455)
+!461 = !DILocation(line: 26, column: 5, scope: !455)
+!462 = !DILocation(line: 30, column: 2, scope: !455)
+!463 = !DILocation(line: 28, column: 35, scope: !455)
+!464 = !DILocation(line: 28, column: 14, scope: !455)
+!465 = distinct !DISubprogram(name: "odd_with_tail", linkageName: "_ZN14tail_call_test13odd_with_tail17hc95516150aaddcc1E", scope: !435, file: !434, line: 32, type: !456, scopeLine: 32, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !466)
+!466 = !{!467}
+!467 = !DILocalVariable(name: "n", arg: 1, scope: !465, file: !434, line: 32, type: !178)
+!468 = !DILocation(line: 32, column: 22, scope: !465)
+!469 = !DILocation(line: 33, column: 5, scope: !465)
+!470 = !DILocation(line: 37, column: 2, scope: !465)
+!471 = !DILocation(line: 35, column: 36, scope: !465)
+!472 = !DILocation(line: 35, column: 14, scope: !465)
+!473 = distinct !DISubprogram(name: "even_no_tail", linkageName: "_ZN14tail_call_test12even_no_tail17hd3be8e5729868b97E", scope: !435, file: !434, line: 41, type: !456, scopeLine: 41, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !474)
+!474 = !{!475}
+!475 = !DILocalVariable(name: "n", arg: 1, scope: !473, file: !434, line: 41, type: !178)
+!476 = !DILocation(line: 41, column: 21, scope: !473)
+!477 = !DILocation(line: 42, column: 5, scope: !473)
+!478 = !DILocation(line: 43, column: 14, scope: !473)
+!479 = !DILocation(line: 44, column: 26, scope: !473)
+!480 = !DILocation(line: 46, column: 2, scope: !473)
+!481 = !DILocation(line: 44, column: 14, scope: !473)
+!482 = distinct !DISubprogram(name: "odd_no_tail", linkageName: "_ZN14tail_call_test11odd_no_tail17h1399b4ae4de50274E", scope: !435, file: !434, line: 48, type: !456, scopeLine: 48, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !29, templateParams: !23, retainedNodes: !483)
+!483 = !{!484}
+!484 = !DILocalVariable(name: "n", arg: 1, scope: !482, file: !434, line: 48, type: !178)
+!485 = !DILocation(line: 48, column: 20, scope: !482)
+!486 = !DILocation(line: 49, column: 5, scope: !482)
+!487 = !DILocation(line: 50, column: 14, scope: !482)
+!488 = !DILocation(line: 51, column: 27, scope: !482)
+!489 = !DILocation(line: 53, column: 2, scope: !482)
+!490 = !DILocation(line: 51, column: 14, scope: !482)
+!491 = distinct !DISubprogram(name: "main", linkageName: "_ZN14tail_call_test4main17h34b192e87b023961E", scope: !435, file: !434, line: 55, type: !21, scopeLine: 55, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagMainSubprogram, unit: !29, templateParams: !23, retainedNodes: !492)
+!492 = !{!493, !495, !497, !499, !501, !503}
+!493 = !DILocalVariable(name: "with_tail_result", scope: !494, file: !434, line: 57, type: !178, align: 32)
+!494 = distinct !DILexicalBlock(scope: !491, file: !434, line: 57, column: 5)
+!495 = !DILocalVariable(name: "no_tail_result", scope: !496, file: !434, line: 58, type: !178, align: 32)
+!496 = distinct !DILexicalBlock(scope: !494, file: !434, line: 58, column: 5)
+!497 = !DILocalVariable(name: "even_with_tail_result", scope: !498, file: !434, line: 59, type: !238, align: 8)
+!498 = distinct !DILexicalBlock(scope: !496, file: !434, line: 59, column: 5)
+!499 = !DILocalVariable(name: "odd_with_tail_result", scope: !500, file: !434, line: 60, type: !238, align: 8)
+!500 = distinct !DILexicalBlock(scope: !498, file: !434, line: 60, column: 5)
+!501 = !DILocalVariable(name: "even_no_tail_result", scope: !502, file: !434, line: 61, type: !238, align: 8)
+!502 = distinct !DILexicalBlock(scope: !500, file: !434, line: 61, column: 5)
+!503 = !DILocalVariable(name: "odd_no_tail_result", scope: !504, file: !434, line: 62, type: !238, align: 8)
+!504 = distinct !DILexicalBlock(scope: !502, file: !434, line: 62, column: 5)
+!505 = !DILocation(line: 57, column: 9, scope: !494)
+!506 = !DILocation(line: 58, column: 9, scope: !496)
+!507 = !DILocation(line: 59, column: 9, scope: !498)
+!508 = !DILocation(line: 60, column: 9, scope: !500)
+!509 = !DILocation(line: 61, column: 9, scope: !502)
+!510 = !DILocation(line: 62, column: 9, scope: !504)
+!511 = !DILocation(line: 57, column: 28, scope: !491)
+!512 = !DILocation(line: 58, column: 26, scope: !494)
+!513 = !DILocation(line: 59, column: 33, scope: !496)
+!514 = !DILocation(line: 60, column: 32, scope: !498)
+!515 = !DILocation(line: 61, column: 31, scope: !500)
+!516 = !DILocation(line: 62, column: 30, scope: !502)
+!517 = !DILocation(line: 64, column: 5, scope: !504)
+!518 = !DILocation(line: 71, column: 2, scope: !519)
+!519 = !DILexicalBlockFile(scope: !491, file: !434, discriminator: 0)
diff --git a/tests/run-make/tail-call-llvm-ir/tail-call-test.rs b/tests/run-make/tail-call-llvm-ir/tail-call-test.rs
new file mode 100644
index 0000000000000..d13192cd87cad
--- /dev/null
+++ b/tests/run-make/tail-call-llvm-ir/tail-call-test.rs
@@ -0,0 +1,65 @@
+#![feature(explicit_tail_calls)]
+
+// A recursive function that uses explicit tail calls with 'become'
+// This should generate LLVM IR with "tail call" instructions
+pub fn with_tail(n: u32) -> u32 {
+ if n == 0 { 0 } else { become with_tail(n - 1) }
+}
+
+// A similar recursive function but without 'become'
+// This should NOT generate tail call instructions by default
+pub fn no_tail(n: u32) -> u32 {
+ if n == 0 { 0 } else { no_tail(n - 1) }
+}
+
+// Mutual recursion with 'become'
+// Both functions should generate tail call instructions
+pub fn even_with_tail(n: u32) -> bool {
+ match n {
+ 0 => true,
+ _ => become odd_with_tail(n - 1),
+ }
+}
+
+pub fn odd_with_tail(n: u32) -> bool {
+ match n {
+ 0 => false,
+ _ => become even_with_tail(n - 1),
+ }
+}
+
+// For comparison: mutual recursion without 'become'
+// These should NOT generate tail call instructions
+pub fn even_no_tail(n: u32) -> bool {
+ match n {
+ 0 => true,
+ _ => odd_no_tail(n - 1),
+ }
+}
+
+pub fn odd_no_tail(n: u32) -> bool {
+ match n {
+ 0 => false,
+ _ => even_no_tail(n - 1),
+ }
+}
+
+fn main() {
+ // Actually use all the functions to ensure they're not optimized away
+ let with_tail_result = with_tail(5);
+ let no_tail_result = no_tail(5);
+ let even_with_tail_result = even_with_tail(10);
+ let odd_with_tail_result = odd_with_tail(10);
+ let even_no_tail_result = even_no_tail(10);
+ let odd_no_tail_result = odd_no_tail(10);
+
+ println!(
+ "Results: {} {} {} {} {} {}",
+ with_tail_result,
+ no_tail_result,
+ even_with_tail_result,
+ odd_with_tail_result,
+ even_no_tail_result,
+ odd_no_tail_result
+ );
+}
diff --git a/tests/run-make/tail-call-llvm-ir/tools.mk b/tests/run-make/tail-call-llvm-ir/tools.mk
new file mode 100644
index 0000000000000..cd076552f4f33
--- /dev/null
+++ b/tests/run-make/tail-call-llvm-ir/tools.mk
@@ -0,0 +1,4 @@
+# Simple Makefile for Rust tests
+
+# Default rustc to use
+RUSTC ?= ../../../build/aarch64-apple-darwin/stage1/bin/rustc
\ No newline at end of file
diff --git a/tests/ui/explicit-tail-calls/llvm-ir-tail-call.rs b/tests/ui/explicit-tail-calls/llvm-ir-tail-call.rs
new file mode 100644
index 0000000000000..e72ee3da033c4
--- /dev/null
+++ b/tests/ui/explicit-tail-calls/llvm-ir-tail-call.rs
@@ -0,0 +1,35 @@
+//@ compile-flags: -O
+//@ run-pass
+#![expect(incomplete_features)]
+#![feature(explicit_tail_calls)]
+
+// A deep recursive function that uses explicit tail calls
+// This will cause stack overflow without tail call optimization
+fn deep_recursion(n: u32) -> u32 {
+ match n {
+ 0 => 0,
+ _ => become deep_recursion(n - 1)
+ }
+}
+
+// A deep recursive function without explicit tail calls
+// This will overflow the stack for large values
+fn deep_recursion_no_tail(n: u32) -> u32 {
+ match n {
+ 0 => 0,
+ _ => deep_recursion_no_tail(n - 1)
+ }
+}
+
+fn main() {
+ // Verify correctness for small values
+ assert_eq!(deep_recursion(10), 0);
+ assert_eq!(deep_recursion_no_tail(10), 0);
+
+ // This will succeed only if tail call optimization is working
+ // It would overflow the stack otherwise
+ println!("Starting deep recursion with 50,000 calls");
+ let result = deep_recursion(50_000);
+ assert_eq!(result, 0);
+ println!("Successfully completed 50,000 recursive calls with tail call optimization");
+}
\ No newline at end of file
diff --git a/tests/ui/explicit-tail-calls/mutual-recursion.rs b/tests/ui/explicit-tail-calls/mutual-recursion.rs
new file mode 100644
index 0000000000000..cb037ce2f20b0
--- /dev/null
+++ b/tests/ui/explicit-tail-calls/mutual-recursion.rs
@@ -0,0 +1,63 @@
+//@ run-pass
+#![expect(incomplete_features)]
+#![feature(explicit_tail_calls)]
+
+// This is a classic example of mutual recursion:
+// even(n) calls odd(n-1), and odd(n) calls even(n-1)
+// Without tail calls, this would quickly overflow the stack for large inputs
+
+// Check if a number is even using mutual recursion
+fn is_even(n: u64) -> bool {
+ match n {
+ 0 => true,
+ _ => become is_odd(n - 1)
+ }
+}
+
+// Check if a number is odd using mutual recursion
+fn is_odd(n: u64) -> bool {
+ match n {
+ 0 => false,
+ _ => become is_even(n - 1)
+ }
+}
+
+// Versions without tail calls for comparison
+fn is_even_no_tail(n: u64) -> bool {
+ match n {
+ 0 => true,
+ _ => is_odd_no_tail(n - 1)
+ }
+}
+
+fn is_odd_no_tail(n: u64) -> bool {
+ match n {
+ 0 => false,
+ _ => is_even_no_tail(n - 1)
+ }
+}
+
+fn main() {
+ // Verify correctness for small values
+ assert_eq!(is_even(0), true);
+ assert_eq!(is_odd(0), false);
+ assert_eq!(is_even(1), false);
+ assert_eq!(is_odd(1), true);
+ assert_eq!(is_even(10), true);
+ assert_eq!(is_odd(10), false);
+
+ // Test with an extremely large number that would definitely overflow the stack
+ // without tail call optimization - each call creates 2 stack frames (alternating between functions)
+ // so 100,000 would create 200,000 stack frames total
+ assert_eq!(is_even(100_000), true);
+ assert_eq!(is_odd(100_000), false);
+ assert_eq!(is_even(100_001), false);
+ assert_eq!(is_odd(100_001), true);
+
+ println!("Deep mutual recursion test passed with 100,000 alternating recursive calls!");
+
+ // Verify non-tail versions work for small values
+ assert_eq!(is_even_no_tail(10), true);
+ assert_eq!(is_odd_no_tail(10), false);
+ // But would overflow for large values (not tested to avoid crashing)
+}
\ No newline at end of file
diff --git a/tests/ui/explicit-tail-calls/runtime-deep-recursion.rs b/tests/ui/explicit-tail-calls/runtime-deep-recursion.rs
new file mode 100644
index 0000000000000..5ab45c76875bc
--- /dev/null
+++ b/tests/ui/explicit-tail-calls/runtime-deep-recursion.rs
@@ -0,0 +1,38 @@
+//@ run-pass
+#![expect(incomplete_features)]
+#![feature(explicit_tail_calls)]
+
+// A function that causes deep recursion - counts down from n to 0
+// Without tail calls, this would overflow the stack for large n values
+fn countdown(n: u32) -> u32 {
+ match n {
+ 0 => 0,
+ _ => become countdown(n - 1)
+ }
+}
+
+// Same function but without tail call optimization
+fn countdown_no_tail(n: u32) -> u32 {
+ match n {
+ 0 => 0,
+ _ => countdown_no_tail(n - 1)
+ }
+}
+
+// This test is specifically designed to verify tail call optimization
+// We use an extremely large recursion depth (500,000) that would
+// absolutely overflow the stack without tail call optimization
+fn main() {
+ // Small test to verify correctness
+ assert_eq!(countdown(10), 0);
+
+ // Regular recursion would overflow here (500,000 stack frames)
+ // Only works if tail call optimization is actually happening
+ let result = countdown(500_000);
+ assert_eq!(result, 0);
+ println!("Successfully completed 500,000 recursive calls with tail call optimization");
+
+ // We can't test the non-tail version with a large number as it would crash,
+ // but we can verify it works for small values
+ assert_eq!(countdown_no_tail(10), 0);
+}
\ No newline at end of file