rust_for_linux: -Zregparm=<N> commandline flag for X86 (rust-lang#116972)

Author: azhogin

src/builder.rs

@@ -30,7 +30,7 @@ use rustc_middle::ty::{Instance, ParamEnv, Ty, TyCtxt};
 use rustc_span::Span;
 use rustc_span::def_id::DefId;
 use rustc_target::abi::call::FnAbi;
-use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, Target, WasmCAbi};
+use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, WasmCAbi, X86Abi};
 
 use crate::common::{SignType, TypeReflection, type_is_pointer};
 use crate::context::CodegenCx;
@@ -2347,6 +2347,12 @@ impl<'tcx> HasWasmCAbiOpt for Builder<'_, '_, 'tcx> {
     }
 }
 
+impl<'tcx> HasX86AbiOpt for Builder<'_, '_, 'tcx> {
+    fn x86_abi_opt(&self) -> X86Abi {
+        self.cx.x86_abi_opt()
+    }
+}
+
 pub trait ToGccComp {
     fn to_gcc_comparison(&self) -> ComparisonOp;
 }

src/context.rs

@@ -19,7 +19,9 @@ 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, Target, TlsModel, WasmCAbi};
+use rustc_target::spec::{
+    HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, TlsModel, WasmCAbi, X86Abi,
+};
 
 use crate::callee::get_fn;
 use crate::common::SignType;
@@ -538,6 +540,12 @@ impl<'gcc, 'tcx> HasWasmCAbiOpt for CodegenCx<'gcc, 'tcx> {
     }
 }
 
+impl<'gcc, 'tcx> HasX86AbiOpt for CodegenCx<'gcc, 'tcx> {
+    fn x86_abi_opt(&self) -> X86Abi {
+        X86Abi { regparm: self.tcx.sess.opts.unstable_opts.regparm }
+    }
+}
+
 impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
     #[inline]
     fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {