[PATCH] D60349: [COFF, ARM64] Fix ABI implementation of struct returns

[Mandeep Singh Grang via Phabricator via cfe-commits]

mgrang created this revision.
mgrang added reviewers: rnk, efriedma, TomTan, ssijaric.
Herald added subscribers: kristof.beyls, javed.absar.
Herald added a project: clang.

Related llvm patch: D60348 <https://reviews.llvm.org/D60348>.


Repository:
  rC Clang

https://reviews.llvm.org/D60349

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


Index: test/CodeGen/arm64-microsoft-arguments.cpp
===================================================================
--- test/CodeGen/arm64-microsoft-arguments.cpp
+++ test/CodeGen/arm64-microsoft-arguments.cpp
@@ -14,7 +14,7 @@
 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: define {{.*}} void @{{.*}}foo{{.*}}(%struct.non_pod* inreg noalias sret %agg.result)
 
 
 // Check instance methods.
@@ -22,4 +22,4 @@
 struct Baz { pod2 baz(); };
 
 int qux() { return Baz().baz().x; }
-// CHECK: declare {{.*}} void @{{.*}}baz@Baz{{.*}}(%struct.Baz*, %struct.pod2*)
+// CHECK: declare {{.*}} void @{{.*}}baz@Baz{{.*}}(%struct.Baz*, %struct.pod2* sret)
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1056,28 +1056,25 @@
   if (!RD)
     return false;
 
+  // Note: The "inreg" attribute is used to signal that the struct return
+  // should be in X0.
+  bool sretInX0 = (CGM.getTarget().getTriple().getArch() ==
+                   llvm::Triple::aarch64) && !RD->isPOD();
+
   CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
   if (FI.isInstanceMethod()) {
     // If it's an instance method, aggregates are always returned indirectly via
     // the second parameter.
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
     FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
+    FI.getReturnInfo().setInReg(sretInX0);
 
-    // aarch64-windows requires that instance methods use X1 for the return
-    // address. So for aarch64-windows we do not mark the
-    // return as SRet.
-    FI.getReturnInfo().setSuppressSRet(CGM.getTarget().getTriple().getArch() ==
-                                       llvm::Triple::aarch64);
     return true;
   } else if (!RD->isPOD()) {
     // If it's a free function, non-POD types are returned indirectly.
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
+    FI.getReturnInfo().setInReg(sretInX0);
 
-    // aarch64-windows requires that non-POD, non-instance returns use X0 for
-    // the return address. So for aarch64-windows we do not mark the return as
-    // SRet.
-    FI.getReturnInfo().setSuppressSRet(CGM.getTarget().getTriple().getArch() ==
-                                       llvm::Triple::aarch64);
     return true;
   }
 
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ 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);
Index: include/clang/CodeGen/CGFunctionInfo.h
===================================================================
--- include/clang/CodeGen/CGFunctionInfo.h
+++ include/clang/CodeGen/CGFunctionInfo.h
@@ -95,7 +95,6 @@
   bool InReg : 1;           // isDirect() || isExtend() || isIndirect()
   bool CanBeFlattened: 1;   // isDirect()
   bool SignExt : 1;         // isExtend()
-  bool SuppressSRet : 1;    // isIndirect()
 
   bool canHavePaddingType() const {
     return isDirect() || isExtend() || isIndirect() || isExpand();
@@ -111,14 +110,13 @@
   }
 
   ABIArgInfo(Kind K)
-      : TheKind(K), PaddingInReg(false), InReg(false), SuppressSRet(false) {
+      : TheKind(K), PaddingInReg(false), InReg(false) {
   }
 
 public:
   ABIArgInfo()
       : TypeData(nullptr), PaddingType(nullptr), DirectOffset(0),
-        TheKind(Direct), PaddingInReg(false), InReg(false),
-        SuppressSRet(false) {}
+        TheKind(Direct), PaddingInReg(false), InReg(false) {}
 
   static ABIArgInfo getDirect(llvm::Type *T = nullptr, unsigned Offset = 0,
                               llvm::Type *Padding = nullptr,
@@ -407,16 +405,6 @@
     CanBeFlattened = Flatten;
   }
 
-  bool getSuppressSRet() const {
-    assert(isIndirect() && "Invalid kind!");
-    return SuppressSRet;
-  }
-
-  void setSuppressSRet(bool Suppress) {
-    assert(isIndirect() && "Invalid kind!");
-    SuppressSRet = Suppress;
-  }
-
   void dump() const;
 };
 

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