From 39b8b2b623087fa643daeed424bd2fa79076f463 Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Sat, 14 Nov 2020 19:16:43 +0100
Subject: [PATCH] Remove StructRet arg attr

It is applied exactly when the return value has an indirect pass mode.
Except for InReg on x86 fastcall, arg attrs are now only used for
optimization purposes and thus are fine to ignore.
---
 compiler/rustc_codegen_llvm/src/abi.rs    | 9 ++++++---
 compiler/rustc_middle/src/ty/layout.rs    | 4 ----
 compiler/rustc_target/src/abi/call/mod.rs | 5 -----
 3 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index e988fdb9d5c5..bb152104d64d 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -36,7 +36,7 @@ impl ArgAttributeExt for ArgAttribute {
     where
         F: FnMut(llvm::Attribute),
     {
-        for_each_kind!(self, f, NoAlias, NoCapture, NonNull, ReadOnly, StructRet, InReg)
+        for_each_kind!(self, f, NoAlias, NoCapture, NonNull, ReadOnly, InReg)
     }
 }
 
@@ -429,7 +429,8 @@ impl<'tcx> FnAbiLlvmExt<'tcx> for FnAbi<'tcx, Ty<'tcx>> {
             }
             PassMode::Indirect { ref attrs, extra_attrs: _, on_stack } => {
                 assert!(!on_stack);
-                apply(attrs);
+                let i = apply(attrs);
+                llvm::Attribute::StructRet.apply_llfn(llvm::AttributePlace::Argument(i), llfn);
             }
             _ => {}
         }
@@ -484,7 +485,9 @@ impl<'tcx> FnAbiLlvmExt<'tcx> for FnAbi<'tcx, Ty<'tcx>> {
             }
             PassMode::Indirect { ref attrs, extra_attrs: _, on_stack } => {
                 assert!(!on_stack);
-                apply(attrs);
+                let i = apply(attrs);
+                llvm::Attribute::StructRet
+                    .apply_callsite(llvm::AttributePlace::Argument(i), callsite);
             }
             _ => {}
         }
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 24d2ee6ec34a..666160ba4976 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2801,10 +2801,6 @@ where
             for arg in &mut self.args {
                 fixup(arg, false);
             }
-            if let PassMode::Indirect { ref mut attrs, extra_attrs: _, on_stack: _ } = self.ret.mode
-            {
-                attrs.set(ArgAttribute::StructRet);
-            }
             return;
         }
 
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index 0931e8a37714..91b004c41d95 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -59,7 +59,6 @@ mod attr_impl {
             const NoCapture = 1 << 2;
             const NonNull   = 1 << 3;
             const ReadOnly  = 1 << 4;
-            const StructRet = 1 << 6;
             const InReg     = 1 << 8;
         }
     }
@@ -619,10 +618,6 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             a => return Err(format!("unrecognized arch \"{}\" in target specification", a)),
         }
 
-        if let PassMode::Indirect { ref mut attrs, extra_attrs: _, on_stack: _ } = self.ret.mode {
-            attrs.set(ArgAttribute::StructRet);
-        }
-
         Ok(())
     }
 }