compiler: Revert -Zregparm handling for extern Rust

Author: workingjubilee

compiler/rustc_target/src/callconv/mod.rs

@@ -720,28 +720,6 @@ impl<'a, Ty> FnAbi<'a, Ty> {
 
         Ok(())
     }
-
-    pub fn fill_inregs_for_rust_abi<C>(&mut self, cx: &C)
-    where
-        Ty: TyAbiInterface<'a, C> + Copy,
-        C: HasTargetSpec + HasX86AbiOpt,
-    {
-        let spec = cx.target_spec();
-        match &spec.arch[..] {
-            "x86" => {
-                x86::fill_inregs(
-                    cx,
-                    self,
-                    x86::X86Options {
-                        flavor: x86::Flavor::General,
-                        regparm: cx.x86_abi_opt().regparm,
-                    },
-                    true,
-                );
-            }
-            _ => {}
-        }
-    }
 }
 
 impl FromStr for Conv {

compiler/rustc_ty_utils/src/abi.rs

@@ -797,9 +797,6 @@ fn fn_abi_adjust_for_abi<'tcx>(
         for (arg_idx, arg) in fn_abi.args.iter_mut().enumerate() {
             fixup(arg, Some(arg_idx));
         }
-        if tcx.sess.target.arch == "x86" {
-            fn_abi.fill_inregs_for_rust_abi(cx);
-        }
     } else {
         fn_abi
             .adjust_for_foreign_abi(cx, abi)

tests/codegen/regparm-inreg-rust-cc.rs

@@ -25,13 +25,6 @@ pub mod tests {
     #[no_mangle]
     pub extern "fastcall" fn f1(_: i32, _: i32, _: i32) {}
 
-    // regparm0: @f2(i32 noundef %_1, i32 noundef %_2, i32 noundef %_3)
-    // regparm1: @f2(i32 inreg noundef %_1, i32 noundef %_2, i32 noundef %_3)
-    // regparm2: @f2(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 noundef %_3)
-    // regparm3: @f2(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 inreg noundef %_3)
-    #[no_mangle]
-    pub extern "Rust" fn f2(_: i32, _: i32, _: i32) {}
-
     // regparm0: @f3(i32 noundef %_1, i32 noundef %_2, i32 noundef %_3)
     // regparm1: @f3(i32 inreg noundef %_1, i32 noundef %_2, i32 noundef %_3)
     // regparm2: @f3(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 noundef %_3)