[i386 ABI] expand small C like structs in C++, just like how we handle small

C structs.

This comes up when we have a function that takes a struct and is defined in a
C++ file and used in a C file.

Before this commit, we will generate byval for C++ and will expand the struct
for C, thus causing difference at IR level. We will use bitcast of function type
at the callsite, which causes the inliner to not inline the function.

This commit changes how we handle small C like structs at IR level, but at
backend, we should generate the same argument passing before and after the
commit.

Note that the condition for expanding is still over conservative. We should be
able to expand type that is spelled with “class” and types that are not C-like.
But this commit fixes the inconsistent argument passing between C/C++.

Reviewed by John.

rdar://20121030

llvm-svn: 234033

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 081895f1e9a21b793933055791b099fe27adff9b..c217273bc0d9e86f3ec50101845d20cb2f6d5bf6 100644 (file)
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -339,9 +339,15 @@ static bool canExpandIndirectArgument(QualType Ty, ASTContext &Context) {
   //
   // FIXME: This needs to be generalized to handle classes as well.
   const RecordDecl *RD = RT->getDecl();
-  if (!RD->isStruct() || isa<CXXRecordDecl>(RD))
+  if (!RD->isStruct())
     return false;
 
+  // We try to expand CLike CXXRecordDecl.
+  if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
+    if (!CXXRD->isCLike())
+      return false;
+  }
+
   uint64_t Size = 0;
 
   for (const auto *FD : RD->fields()) {

diff --git a/clang/test/CodeGenCXX/call-with-static-chain.cpp b/clang/test/CodeGenCXX/call-with-static-chain.cpp
index 7cf929189f2cf1a5f5e543777cefa7476aedcd1e..ac1149b52eddf7bb705f1ddd4345a225ded36b2f 100644 (file)
--- a/clang/test/CodeGenCXX/call-with-static-chain.cpp
+++ b/clang/test/CodeGenCXX/call-with-static-chain.cpp
@@ -21,7 +21,7 @@ A &f4();
 void test() {
   A a;
 
-  // CHECK32: call i32 bitcast (i32 (%struct.A*, %struct.A*, %struct.A*, %struct.A*)* @f1 to i32 (i8*, %struct.A*, %struct.A*, %struct.A*, %struct.A*)*)(i8* nest bitcast (i32 (%struct.A*, %struct.A*, %struct.A*, %struct.A*)* @f1 to i8*)
+  // CHECK32: call i32 bitcast (i32 (i32, i32, i32, i32, i32, i32, i32, i32)* @f1 to i32 (i8*, i32, i32, i32, i32, i32, i32, i32, i32)*)(i8* nest bitcast (i32 (i32, i32, i32, i32, i32, i32, i32, i32)* @f1 to i8*)
   // CHECK64: call i32 bitcast (i32 (i64, i64, i64, i64, i64, i64, %struct.A*)* @f1 to i32 (i8*, i64, i64, i64, i64, i64, i64, %struct.A*)*)(i8* nest bitcast (i32 (i64, i64, i64, i64, i64, i64, %struct.A*)* @f1 to i8*)
   __builtin_call_with_static_chain(f1(a, a, a, a), f1);
 

diff --git a/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp b/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
index a4eaa1cfbc1b99645fb5ee60713d7dad7c5e55f3..4c2d8506af7089cec60da8b0ba2b9e3ca5caa0b8 100644 (file)
--- a/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
@@ -101,12 +101,12 @@ Big big_return() { return Big(); }
 
 
 void small_arg(Small s) {}
-// LINUX-LABEL: define void @_Z9small_arg5Small(%struct.Small* byval align 4 %s)
+// LINUX-LABEL: define void @_Z9small_arg5Small(i32 %s.0)
 // WIN32: define void @"\01?small_arg@@YAXUSmall@@@Z"(%struct.Small* byval align 4 %s)
 // WIN64: define void @"\01?small_arg@@YAXUSmall@@@Z"(i32 %s.coerce)
 
 void medium_arg(Medium s) {}
-// LINUX-LABEL: define void @_Z10medium_arg6Medium(%struct.Medium* byval align 4 %s)
+// LINUX-LABEL: define void @_Z10medium_arg6Medium(i32 %s.0, i32 %s.1)
 // WIN32: define void @"\01?medium_arg@@YAXUMedium@@@Z"(%struct.Medium* byval align 4 %s)
 // WIN64: define void @"\01?medium_arg@@YAXUMedium@@@Z"(i64 %s.coerce)
 
@@ -229,7 +229,7 @@ class Class {
   // WIN64: define linkonce_odr void @"\01?thiscall_method_arg@Class@@QEAAXUEmptyWithCtor@@@Z"(%class.Class* %this, i8 %s.coerce)
 
   void thiscall_method_arg(Small s) {}
-  // LINUX: define {{.*}} void @_ZN5Class19thiscall_method_argE5Small(%class.Class* %this, %struct.Small* byval align 4 %s)
+  // LINUX: define {{.*}} void @_ZN5Class19thiscall_method_argE5Small(%class.Class* %this, i32 %s.0)
   // WIN32: define {{.*}} void @"\01?thiscall_method_arg@Class@@QAEXUSmall@@@Z"(%class.Class* %this, %struct.Small* byval align 4 %s)
   // WIN64: define linkonce_odr void @"\01?thiscall_method_arg@Class@@QEAAXUSmall@@@Z"(%class.Class* %this, i32 %s.coerce)