Introduce perma-unstable wasm-c-abi flag

Author: daxpedda

compiler/rustc_codegen_gcc/src/builder.rs

@@ -31,7 +31,7 @@ use rustc_span::Span;
 use rustc_target::abi::{
 self, call::FnAbi,Align,HasDataLayout,Size,TargetDataLayout,WrappingRange,
 };
-use rustc_target::spec::{HasTargetSpec,Target};
+use rustc_target::spec::{HasTargetSpec,HasWasmCAbiOpt,Target,WasmCAbi};
 
 usecrate::common::{type_is_pointer,SignType,TypeReflection};
 usecrate::context::CodegenCx;
@@ -2349,6 +2349,12 @@ impl<'tcx> HasTargetSpec for Builder<'_, '_, 'tcx> {
 }
 }
 
+impl<'tcx>HasWasmCAbiOptforBuilder<'_,'_,'tcx>{
+fnwasm_c_abi_opt(&self) -> WasmCAbi{
+self.cx.wasm_c_abi_opt()
+}
+}
+
 pubtraitToGccComp{
 fnto_gcc_comparison(&self) -> ComparisonOp;
 }

compiler/rustc_codegen_gcc/src/context.rs

@@ -20,7 +20,7 @@ use rustc_span::{source_map::respan, Span};
 use rustc_target::abi::{
  call::FnAbi,HasDataLayout,PointeeInfo,Size,TargetDataLayout,VariantIdx,
 };
-use rustc_target::spec::{HasTargetSpec,Target,TlsModel};
+use rustc_target::spec::{HasTargetSpec,HasWasmCAbiOpt,Target,TlsModel,WasmCAbi};
 
 usecrate::callee::get_fn;
 usecrate::common::SignType;
@@ -555,6 +555,12 @@ impl<'gcc, 'tcx> HasTargetSpec for CodegenCx<'gcc, 'tcx> {
 }
 }
 
+impl<'gcc,'tcx>HasWasmCAbiOptforCodegenCx<'gcc,'tcx>{
+fnwasm_c_abi_opt(&self) -> WasmCAbi{
+self.tcx.sess.opts.unstable_opts.wasm_c_abi
+}
+}
+
 impl<'gcc,'tcx>LayoutOfHelpers<'tcx>forCodegenCx<'gcc,'tcx>{
 typeLayoutOfResult = TyAndLayout<'tcx>;
 

compiler/rustc_interface/src/tests.rs

@@ -17,7 +17,9 @@ use rustc_session::{build_session, getopts, CompilerIO, EarlyDiagCtxt, Session};
 use rustc_span::edition::{Edition,DEFAULT_EDITION};
 use rustc_span::symbol::sym;
 use rustc_span::{FileName,SourceFileHashAlgorithm};
-use rustc_target::spec::{CodeModel,LinkerFlavorCli,MergeFunctions,PanicStrategy,RelocModel};
+use rustc_target::spec::{
+CodeModel,LinkerFlavorCli,MergeFunctions,PanicStrategy,RelocModel,WasmCAbi,
+};
 use rustc_target::spec::{RelroLevel,SanitizerSet,SplitDebuginfo,StackProtector,TlsModel};
 use std::collections::{BTreeMap,BTreeSet};
 use std::num::NonZero;
@@ -836,6 +838,7 @@ 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

@@ -15,7 +15,9 @@ use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{ErrorGuaranteed,Span,DUMMY_SP};
 use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::*;
-use rustc_target::spec::{abi::AbiasSpecAbi,HasTargetSpec,PanicStrategy,Target};
+use rustc_target::spec::{
+ abi::AbiasSpecAbi,HasTargetSpec,HasWasmCAbiOpt,PanicStrategy,Target,WasmCAbi,
+};
 
 use std::borrow::Cow;
 use std::cmp;
@@ -539,6 +541,12 @@ impl<'tcx> HasTargetSpec for TyCtxt<'tcx> {
 }
 }
 
+impl<'tcx>HasWasmCAbiOptforTyCtxt<'tcx>{
+fnwasm_c_abi_opt(&self) -> WasmCAbi{
+self.sess.opts.unstable_opts.wasm_c_abi
+}
+}
+
 impl<'tcx>HasTyCtxt<'tcx>forTyCtxt<'tcx>{
 #[inline]
 fntcx(&self) -> TyCtxt<'tcx>{
@@ -584,6 +592,12 @@ impl<'tcx, T: HasTargetSpec> HasTargetSpec for LayoutCx<'tcx, T> {
 }
 }
 
+impl<'tcx,T:HasWasmCAbiOpt>HasWasmCAbiOptforLayoutCx<'tcx,T>{
+fnwasm_c_abi_opt(&self) -> WasmCAbi{
+self.tcx.wasm_c_abi_opt()
+}
+}
+
 impl<'tcx,T:HasTyCtxt<'tcx>>HasTyCtxt<'tcx>forLayoutCx<'tcx,T>{
 fntcx(&self) -> TyCtxt<'tcx>{
 self.tcx.tcx()

compiler/rustc_session/src/config.rs

@@ -3227,7 +3227,7 @@ pub(crate) mod dep_tracking {
 use rustc_feature::UnstableFeatures;
 use rustc_span::edition::Edition;
 use rustc_span::RealFileName;
-use rustc_target::spec::{CodeModel,MergeFunctions,PanicStrategy,RelocModel};
+use rustc_target::spec::{CodeModel,MergeFunctions,PanicStrategy,RelocModel,WasmCAbi};
 use rustc_target::spec::{
 RelroLevel,SanitizerSet,SplitDebuginfo,StackProtector,TargetTriple,TlsModel,
 };
@@ -3324,6 +3324,7 @@ pub(crate) mod dep_tracking {
 Polonius,
 InliningThreshold,
 FunctionReturn,
+WasmCAbi,
 );
 
 impl<T1,T2>DepTrackingHashfor(T1,T2)

compiler/rustc_session/src/options.rs

@@ -8,7 +8,9 @@ use rustc_data_structures::profiling::TimePassesFormat;
 use rustc_data_structures::stable_hasher::Hash64;
 use rustc_errors::ColorConfig;
 use rustc_errors::{LanguageIdentifier,TerminalUrl};
-use rustc_target::spec::{CodeModel,LinkerFlavorCli,MergeFunctions,PanicStrategy,SanitizerSet};
+use rustc_target::spec::{
+CodeModel,LinkerFlavorCli,MergeFunctions,PanicStrategy,SanitizerSet,WasmCAbi,
+};
 use rustc_target::spec::{
 RelocModel,RelroLevel,SplitDebuginfo,StackProtector,TargetTriple,TlsModel,
 };
@@ -437,6 +439,7 @@ mod desc {
 "either a boolean (`yes`, `no`, `on`, `off`, etc), or a non-negative number";
 pubconst 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`)";
 pubconst parse_function_return:&str = "`keep` or `thunk-extern`";
+pubconst parse_wasm_c_abi:&str = "`legacy` or `spec`";
 }
 
 mod parse {
@@ -1402,6 +1405,15 @@ mod parse {
 }
 true
 }
+
+pub(crate)fnparse_wasm_c_abi(slot:&mutWasmCAbi,v:Option<&str>) -> bool{
+match v {
+Some("spec") => *slot = WasmCAbi::Spec,
+Some("legacy") => *slot = WasmCAbi::Legacy,
+ _ => returnfalse,
+}
+true
+}
 }
 
 options!{
@@ -2021,6 +2033,8 @@ 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/abi/call/mod.rs

@@ -1,6 +1,6 @@
 usecrate::abi::{self,Abi,Align,FieldsShape,Size};
 usecrate::abi::{HasDataLayout,TyAbiInterface,TyAndLayout};
-usecrate::spec::{self,HasTargetSpec};
+usecrate::spec::{self,HasTargetSpec,HasWasmCAbiOpt};
 use rustc_span::Symbol;
 use std::fmt;
 use std::str::FromStr;
@@ -782,7 +782,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
 ) -> Result<(),AdjustForForeignAbiError>
 where
 Ty:TyAbiInterface<'a,C> + Copy,
-C:HasDataLayout + HasTargetSpec,
+C:HasDataLayout + HasTargetSpec + HasWasmCAbiOpt,
 {
 if abi == spec::abi::Abi::X86Interrupt{
 ifletSome(arg) = self.args.first_mut(){
@@ -839,7 +839,9 @@ impl<'a, Ty> FnAbi<'a, Ty> {
 "sparc" => sparc::compute_abi_info(cx,self),
 "sparc64" => sparc64::compute_abi_info(cx,self),
 "nvptx64" => {
-if cx.target_spec().adjust_abi(abi,self.c_variadic) == spec::abi::Abi::PtxKernel{
+if cx.target_spec().adjust_abi(cx, abi,self.c_variadic)
+ == spec::abi::Abi::PtxKernel
+{
  nvptx64::compute_ptx_kernel_abi_info(cx,self)
 }else{
  nvptx64::compute_abi_info(self)
@@ -848,7 +850,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
 "hexagon" => hexagon::compute_abi_info(self),
 "riscv32" | "riscv64" => riscv::compute_abi_info(cx,self),
 "wasm32" | "wasm64" => {
-if cx.target_spec().adjust_abi(abi,self.c_variadic) == spec::abi::Abi::Wasm{
+if cx.target_spec().adjust_abi(cx,abi,self.c_variadic) == spec::abi::Abi::Wasm{
  wasm::compute_wasm_abi_info(self)
 }else{
  wasm::compute_c_abi_info(cx,self)

compiler/rustc_target/src/spec/mod.rs

@@ -1807,6 +1807,19 @@ impl HasTargetSpec for Target {
 }
 }
 
+/// Which C ABI to use for `wasm32-unknown-unknown`.
+#[derive(Debug,Copy,Clone,Hash,PartialEq,Eq)]
+pubenumWasmCAbi{
+/// Spec-compliant C ABI.
+Spec,
+/// Legacy ABI. Which is non-spec-compliant.
+Legacy,
+}
+
+pubtraitHasWasmCAbiOpt{
+fnwasm_c_abi_opt(&self) -> WasmCAbi;
+}
+
 typeStaticCow<T> = Cow<'static,T>;
 
 /// Optional aspects of a target specification.
@@ -2417,9 +2430,21 @@ impl DerefMut for Target {
 
 implTarget{
 /// Given a function ABI, turn it into the correct ABI for this target.
-pubfnadjust_abi(&self,abi:Abi,c_variadic:bool) -> Abi{
+pubfnadjust_abi<C>(&self,cx:&C,abi:Abi,c_variadic:bool) -> Abi
+where
+C:HasWasmCAbiOpt,
+{
 match abi {
-Abi::C{ .. } => self.default_adjusted_cabi.unwrap_or(abi),
+Abi::C{ .. } => {
+ifself.arch == "wasm32"
+ && self.os == "unknown"
+ && cx.wasm_c_abi_opt() == WasmCAbi::Spec
+{
+ abi
+}else{
+self.default_adjusted_cabi.unwrap_or(abi)
+}
+}
 
 // On Windows, `extern "system"` behaves like msvc's `__stdcall`.
 // `__stdcall` only applies on x86 and on non-variadic functions:

compiler/rustc_ty_utils/src/abi.rs

@@ -311,7 +311,7 @@ fn fn_sig_for_fn_abi<'tcx>(
 #[inline]
 fnconv_from_spec_abi(tcx:TyCtxt<'_>,abi:SpecAbi,c_variadic:bool) -> Conv{
 use rustc_target::spec::abi::Abi::*;
-match tcx.sess.target.adjust_abi(abi, c_variadic){
+match tcx.sess.target.adjust_abi(&tcx,abi, c_variadic){
 RustIntrinsic | Rust | RustCall => Conv::Rust,
 
 // This is intentionally not using `Conv::Cold`, as that has to preserve

src/doc/unstable-book/src/compiler-flags/wasm-c-abi.md

@@ -0,0 +1,10 @@
+# `wasm-c-abi`
+
+This option controls whether Rust uses the spec-compliant C ABI when compiling
+for the `wasm32-unknown-unknown` target.
+
+This makes it possible to be ABI-compatible with all other spec-compliant Wasm
+like Rusts `wasm32-wasi`.
+
+This compiler flag is perma-unstable, as it will be enabled by default in the
+future with no option to fall back to the old non-spec-compliant ABI.