Remove all support for wasm's legacy ABI

Author: bjorn3

compiler/rustc_codegen_gcc/src/builder.rs

@@ -30,7 +30,7 @@ use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_span::Span;
 use rustc_span::def_id::DefId;
 use rustc_target::abi::call::FnAbi;
-use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, WasmCAbi, X86Abi};
+use rustc_target::spec::{HasTargetSpec, HasX86AbiOpt, Target, X86Abi};
 
 use crate::common::{SignType, TypeReflection, type_is_pointer};
 use crate::context::CodegenCx;
@@ -2331,12 +2331,6 @@ impl<'tcx> HasTargetSpec for Builder<'_, '_, 'tcx> {
     }
 }
 
-impl<'tcx> HasWasmCAbiOpt for Builder<'_, '_, 'tcx> {
-    fn wasm_c_abi_opt(&self) -> WasmCAbi {
-        self.cx.wasm_c_abi_opt()
-    }
-}
-
 impl<'tcx> HasX86AbiOpt for Builder<'_, '_, 'tcx> {
     fn x86_abi_opt(&self) -> X86Abi {
         self.cx.x86_abi_opt()

compiler/rustc_codegen_gcc/src/context.rs

@@ -19,9 +19,7 @@ use rustc_session::Session;
 use rustc_span::source_map::respan;
 use rustc_span::{DUMMY_SP, Span};
 use rustc_target::abi::{HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
-use rustc_target::spec::{
-    HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, TlsModel, WasmCAbi, X86Abi,
-};
+use rustc_target::spec::{HasTargetSpec, HasX86AbiOpt, Target, TlsModel, X86Abi};
 
 use crate::callee::get_fn;
 use crate::common::SignType;
@@ -536,12 +534,6 @@ impl<'gcc, 'tcx> HasTargetSpec for CodegenCx<'gcc, 'tcx> {
     }
 }
 
-impl<'gcc, 'tcx> HasWasmCAbiOpt for CodegenCx<'gcc, 'tcx> {
-    fn wasm_c_abi_opt(&self) -> WasmCAbi {
-        self.tcx.sess.opts.unstable_opts.wasm_c_abi
-    }
-}
-
 impl<'gcc, 'tcx> HasX86AbiOpt for CodegenCx<'gcc, 'tcx> {
     fn x86_abi_opt(&self) -> X86Abi {
         X86Abi {

compiler/rustc_interface/src/tests.rs

@@ -27,7 +27,7 @@ use rustc_span::symbol::sym;
 use rustc_span::{FileName, SourceFileHashAlgorithm};
 use rustc_target::spec::{
     CodeModel, FramePointer, LinkerFlavorCli, MergeFunctions, OnBrokenPipe, PanicStrategy,
-    RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, TlsModel, WasmCAbi,
+    RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, TlsModel,
 };
 
 use crate::interface::{initialize_checked_jobserver, parse_cfg};
@@ -866,7 +866,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(verify_llvm_ir, true);
     tracked!(virtual_function_elimination, true);
     tracked!(wasi_exec_model, Some(WasiExecModel::Reactor));
-    tracked!(wasm_c_abi, WasmCAbi::Spec);
     // tidy-alphabetical-end
 
     macro_rules! tracked_no_crate_hash {

compiler/rustc_middle/src/ty/layout.rs

@@ -19,9 +19,7 @@ use rustc_session::config::OptLevel;
 use rustc_span::symbol::{Symbol, sym};
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span};
 use rustc_target::callconv::FnAbi;
-use rustc_target::spec::{
-    HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, PanicStrategy, Target, WasmCAbi, X86Abi,
-};
+use rustc_target::spec::{HasTargetSpec, HasX86AbiOpt, PanicStrategy, Target, X86Abi};
 use tracing::debug;
 use {rustc_abi as abi, rustc_hir as hir};
 
@@ -544,12 +542,6 @@ impl<'tcx> HasTargetSpec for TyCtxt<'tcx> {
     }
 }
 
-impl<'tcx> HasWasmCAbiOpt for TyCtxt<'tcx> {
-    fn wasm_c_abi_opt(&self) -> WasmCAbi {
-        self.sess.opts.unstable_opts.wasm_c_abi
-    }
-}
-
 impl<'tcx> HasX86AbiOpt for TyCtxt<'tcx> {
     fn x86_abi_opt(&self) -> X86Abi {
         X86Abi {
@@ -604,12 +596,6 @@ impl<'tcx> HasTargetSpec for LayoutCx<'tcx> {
     }
 }
 
-impl<'tcx> HasWasmCAbiOpt for LayoutCx<'tcx> {
-    fn wasm_c_abi_opt(&self) -> WasmCAbi {
-        self.calc.cx.wasm_c_abi_opt()
-    }
-}
-
 impl<'tcx> HasX86AbiOpt for LayoutCx<'tcx> {
     fn x86_abi_opt(&self) -> X86Abi {
         self.calc.cx.x86_abi_opt()

compiler/rustc_session/src/config.rs

@@ -2893,7 +2893,7 @@ pub(crate) mod dep_tracking {
     use rustc_target::spec::{
         CodeModel, FramePointer, MergeFunctions, OnBrokenPipe, PanicStrategy, RelocModel,
         RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, SymbolVisibility, TargetTuple,
-        TlsModel, WasmCAbi,
+        TlsModel,
     };
 
     use super::{
@@ -3002,7 +3002,6 @@ pub(crate) mod dep_tracking {
         Polonius,
         InliningThreshold,
         FunctionReturn,
-        WasmCAbi,
     );
 
     impl<T1, T2> DepTrackingHash for (T1, T2)

compiler/rustc_session/src/options.rs

@@ -14,7 +14,7 @@ use rustc_span::{RealFileName, SourceFileHashAlgorithm};
 use rustc_target::spec::{
     CodeModel, FramePointer, LinkerFlavorCli, MergeFunctions, OnBrokenPipe, PanicStrategy,
     RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, SymbolVisibility,
-    TargetTuple, TlsModel, WasmCAbi,
+    TargetTuple, TlsModel,
 };
 
 use crate::config::*;
@@ -450,7 +450,6 @@ mod desc {
         "either a boolean (`yes`, `no`, `on`, `off`, etc), or a non-negative number";
     pub(crate) const parse_llvm_module_flag: &str = "<key>:<type>:<value>:<behavior>. Type must currently be `u32`. Behavior should be one of (`error`, `warning`, `require`, `override`, `append`, `appendunique`, `max`, `min`)";
     pub(crate) const parse_function_return: &str = "`keep` or `thunk-extern`";
-    pub(crate) const parse_wasm_c_abi: &str = "`legacy` or `spec`";
     pub(crate) const parse_mir_include_spans: &str =
         "either a boolean (`yes`, `no`, `on`, `off`, etc), or `nll` (default: `nll`)";
 }
@@ -1502,15 +1501,6 @@ pub mod parse {
         true
     }
 
-    pub(crate) fn parse_wasm_c_abi(slot: &mut WasmCAbi, v: Option<&str>) -> bool {
-        match v {
-            Some("spec") => *slot = WasmCAbi::Spec,
-            Some("legacy") => *slot = WasmCAbi::Legacy,
-            _ => return false,
-        }
-        true
-    }
-
     pub(crate) fn parse_mir_include_spans(slot: &mut MirIncludeSpans, v: Option<&str>) -> bool {
         *slot = match v {
             Some("on" | "yes" | "y" | "true") | None => MirIncludeSpans::On,
@@ -2181,8 +2171,6 @@ written to standard error output)"),
         Requires `-Clto[=[fat,yes]]`"),
     wasi_exec_model: Option<WasiExecModel> = (None, parse_wasi_exec_model, [TRACKED],
         "whether to build a wasi command or reactor"),
-    wasm_c_abi: WasmCAbi = (WasmCAbi::Legacy, parse_wasm_c_abi, [TRACKED],
-        "use spec-compliant C ABI for `wasm32-unknown-unknown` (default: legacy)"),
     write_long_types_to_disk: bool = (true, parse_bool, [UNTRACKED],
         "whether long type names should be written to files instead of being printed in errors"),
     // tidy-alphabetical-end

compiler/rustc_target/src/callconv/mod.rs

@@ -10,7 +10,7 @@ use crate::abi::{
     TyAndLayout,
 };
 use crate::spec::abi::Abi as SpecAbi;
-use crate::spec::{self, HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, WasmCAbi};
+use crate::spec::{self, HasTargetSpec, HasX86AbiOpt};
 
 mod aarch64;
 mod amdgpu;
@@ -638,7 +638,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
     ) -> Result<(), AdjustForForeignAbiError>
     where
         Ty: TyAbiInterface<'a, C> + Copy,
-        C: HasDataLayout + HasTargetSpec + HasWasmCAbiOpt + HasX86AbiOpt,
+        C: HasDataLayout + HasTargetSpec + HasX86AbiOpt,
     {
         if abi == spec::abi::Abi::X86Interrupt {
             if let Some(arg) = self.args.first_mut() {
@@ -710,14 +710,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             "hexagon" => hexagon::compute_abi_info(self),
             "xtensa" => xtensa::compute_abi_info(cx, self),
             "riscv32" | "riscv64" => riscv::compute_abi_info(cx, self),
-            "wasm32" => {
-                if spec.os == "unknown" && cx.wasm_c_abi_opt() == WasmCAbi::Legacy {
-                    wasm::compute_wasm_abi_info(self)
-                } else {
-                    wasm::compute_c_abi_info(cx, self)
-                }
-            }
-            "wasm64" => wasm::compute_c_abi_info(cx, self),
+            "wasm32" | "wasm64" => wasm::compute_abi_info(cx, self),
             "bpf" => bpf::compute_abi_info(self),
             arch => {
                 return Err(AdjustForForeignAbiError::Unsupported {

compiler/rustc_target/src/callconv/wasm.rs

@@ -45,7 +45,7 @@ where
 }
 
 /// The purpose of this ABI is to match the C ABI (aka clang) exactly.
-pub(crate) fn compute_c_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
+pub(crate) fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
 where
     Ty: TyAbiInterface<'a, C> + Copy,
     C: HasDataLayout,
@@ -61,43 +61,3 @@ where
         classify_arg(cx, arg);
     }
 }
-
-/// The purpose of this ABI is for matching the WebAssembly standard. This
-/// intentionally diverges from the C ABI and is specifically crafted to take
-/// advantage of LLVM's support of multiple returns in WebAssembly.
-///
-/// This ABI is *bad*! It uses `PassMode::Direct` for `abi::Aggregate` types, which leaks LLVM
-/// implementation details into the ABI. It's just hard to fix because ABIs are hard to change.
-/// Also see <https://github.com/rust-lang/rust/issues/115666>.
-pub(crate) fn compute_wasm_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
-    if !fn_abi.ret.is_ignore() {
-        classify_ret_wasm_abi(&mut fn_abi.ret);
-    }
-
-    for arg in fn_abi.args.iter_mut() {
-        if arg.is_ignore() {
-            continue;
-        }
-        classify_arg_wasm_abi(arg);
-    }
-
-    fn classify_ret_wasm_abi<Ty>(ret: &mut ArgAbi<'_, Ty>) {
-        if !ret.layout.is_sized() {
-            // Not touching this...
-            return;
-        }
-        // FIXME: this is bad! https://github.com/rust-lang/rust/issues/115666
-        ret.make_direct_deprecated();
-        ret.extend_integer_width_to(32);
-    }
-
-    fn classify_arg_wasm_abi<Ty>(arg: &mut ArgAbi<'_, Ty>) {
-        if !arg.layout.is_sized() {
-            // Not touching this...
-            return;
-        }
-        // FIXME: this is bad! https://github.com/rust-lang/rust/issues/115666
-        arg.make_direct_deprecated();
-        arg.extend_integer_width_to(32);
-    }
-}

compiler/rustc_target/src/spec/mod.rs

@@ -2098,19 +2098,6 @@ impl HasTargetSpec for Target {
     }
 }
 
-/// Which C ABI to use for `wasm32-unknown-unknown`.
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
-pub enum WasmCAbi {
-    /// Spec-compliant C ABI.
-    Spec,
-    /// Legacy ABI. Which is non-spec-compliant.
-    Legacy,
-}
-
-pub trait HasWasmCAbiOpt {
-    fn wasm_c_abi_opt(&self) -> WasmCAbi;
-}
-
 /// x86 (32-bit) abi options.
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct X86Abi {

compiler/rustc_ty_utils/src/abi.rs

@@ -470,28 +470,18 @@ fn fn_abi_sanity_check<'tcx>(
                         // For an unsized type we'd only pass the sized prefix, so there is no universe
                         // in which we ever want to allow this.
                         assert!(sized, "`PassMode::Direct` for unsized type in ABI: {:#?}", fn_abi);
+
                         // This really shouldn't happen even for sized aggregates, since
                         // `immediate_llvm_type` will use `layout.fields` to turn this Rust type into an
                         // LLVM type. This means all sorts of Rust type details leak into the ABI.
-                        // However wasm sadly *does* currently use this mode for it's "C" ABI so we
-                        // have to allow it -- but we absolutely shouldn't let any more targets do
-                        // that. (Also see <https://github.com/rust-lang/rust/issues/115666>.)
-                        //
-                        // The unadjusted ABI also uses Direct for all args and is ill-specified,
+                        // The unadjusted ABI however uses Direct for all args. It is ill-specified,
                         // but unfortunately we need it for calling certain LLVM intrinsics.
-
-                        match spec_abi {
-                            ExternAbi::Unadjusted => {}
-                            ExternAbi::C { unwind: _ }
-                                if matches!(&*tcx.sess.target.arch, "wasm32" | "wasm64") => {}
-                            _ => {
-                                panic!(
-                                    "`PassMode::Direct` for aggregates only allowed for \"unadjusted\" functions and on wasm\n\
-                                      Problematic type: {:#?}",
-                                    arg.layout,
-                                );
-                            }
-                        }
+                        assert!(
+                            matches!(spec_abi, ExternAbi::Unadjusted),
+                            "`PassMode::Direct` for aggregates only allowed for \"unadjusted\"\n\
+                             Problematic type: {:#?}",
+                            arg.layout,
+                        );
                     }
                 }
             }