[PATCH] D49464: [COFF, ARM64] Mark only POD-type returns as SRET

[Mandeep Singh Grang via Phabricator via llvm-commits]

mgrang updated this revision to Diff 156928.
mgrang added a comment.

Addressed comments.


https://reviews.llvm.org/D49464

Files:
  include/clang/CodeGen/CGFunctionInfo.h
  lib/CodeGen/CGCall.cpp
  lib/CodeGen/TargetInfo.cpp
  test/CodeGen/arm64-microsoft-arguments.cpp


Index: test/CodeGen/arm64-microsoft-arguments.cpp
===================================================================
--- /dev/null
+++ test/CodeGen/arm64-microsoft-arguments.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple aarch64-windows -ffreestanding -emit-llvm \
+// RUN: -x c++ -o - %s | FileCheck %s
+
+struct pod { int a, b, c, d, e; };
+
+struct non_pod {
+  int a;
+  non_pod() {}
+};
+
+struct pod s;
+struct non_pod t;
+
+struct pod bar() { return s; }
+struct non_pod foo() { return t; }
+// CHECK: define {{.*}} void @{{.*}}bar{{.*}}(%struct.pod* noalias sret %agg.result)
+// CHECK: define {{.*}} void @{{.*}}foo{{.*}}(%struct.non_pod* noalias %agg.result)
+
+
+// Check instance methods.
+struct pod2 { int x; };
+struct Baz {
+  pod2 baz() { return pod2 {3}; }
+};
+
+int qux() { return Baz().baz().x; }
+// CHECK: define {{.*}} void @{{.*}}baz at Baz{{.*}}(%struct.Baz* %this, %struct.pod2* noalias sret %agg.result)
Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -4923,6 +4923,8 @@
     if (!::classifyReturnType(getCXXABI(), FI, *this))
       FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
 
+    FI.setSuppressSRet(Kind == Win64);
+
     for (auto &it : FI.arguments())
       it.info = classifyArgumentType(it.type);
   }
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -825,6 +825,7 @@
   FI->NumArgs = argTypes.size();
   FI->HasExtParameterInfos = !paramInfos.empty();
   FI->getArgsBuffer()[0].type = resultType;
+  FI->SuppressSRet = 0;
   for (unsigned i = 0, e = argTypes.size(); i != e; ++i)
     FI->getArgsBuffer()[i + 1].type = argTypes[i];
   for (unsigned i = 0, e = paramInfos.size(); i != e; ++i)
@@ -1984,7 +1985,12 @@
   // Attach attributes to sret.
   if (IRFunctionArgs.hasSRetArg()) {
     llvm::AttrBuilder SRETAttrs;
-    SRETAttrs.addAttribute(llvm::Attribute::StructRet);
+    if (FI.isSuppressSRet()) {
+      const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
+      if (RD && RD->isPOD())
+        SRETAttrs.addAttribute(llvm::Attribute::StructRet);
+    } else
+      SRETAttrs.addAttribute(llvm::Attribute::StructRet);
     hasUsedSRet = true;
     if (RetAI.getInReg())
       SRETAttrs.addAttribute(llvm::Attribute::InReg);
Index: include/clang/CodeGen/CGFunctionInfo.h
===================================================================
--- include/clang/CodeGen/CGFunctionInfo.h
+++ include/clang/CodeGen/CGFunctionInfo.h
@@ -518,6 +518,9 @@
   /// Whether this function has nocf_check attribute.
   unsigned NoCfCheck : 1;
 
+  /// Whether the SRet attribute should be suppressed for this function.
+  unsigned SuppressSRet : 1;
+
   RequiredArgs Required;
 
   /// The struct representing all arguments passed in memory.  Only used when
@@ -605,6 +608,10 @@
   /// Whether this function has nocf_check attribute.
   bool isNoCfCheck() const { return NoCfCheck; }
 
+  /// Whether the SRet attribute should be suppresed for this function.
+  bool isSuppressSRet() const { return SuppressSRet; }
+  void setSuppressSRet(bool Value) { SuppressSRet = Value; }
+
   /// getASTCallingConvention() - Return the AST-specified calling
   /// convention.
   CallingConv getASTCallingConvention() const {


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