[COFF, ARM64] Fix ABI implementation of struct returns

Summary:
Related llvm patch: D60348.
Patch co-authored by Sanjin Sijaric.

Reviewers: rnk, efriedma, TomTan, ssijaric, ostannard

Reviewed By: efriedma

Subscribers: dmajor, richard.townsend.arm, ostannard, javed.absar, kristof.beyls, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60349

llvm-svn: 359932
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index b837fa4..bc9be14 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1999,8 +1999,7 @@
   // Attach attributes to sret.
   if (IRFunctionArgs.hasSRetArg()) {
     llvm::AttrBuilder SRETAttrs;
-    if (!RetAI.getSuppressSRet())
-      SRETAttrs.addAttribute(llvm::Attribute::StructRet);
+    SRETAttrs.addAttribute(llvm::Attribute::StructRet);
     hasUsedSRet = true;
     if (RetAI.getInReg())
       SRETAttrs.addAttribute(llvm::Attribute::InReg);