[WinEH] Don't create an alloca for unnamed catch parameters

The catch object parameter to llvm.eh.begincatch is optional, and can be
null. We can save some ourselves the stack space, copy ctor, and dtor
calls if we pass null.

llvm-svn: 234264

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 2a76203e71c4225cbe5587d72cd127a151935a1f..f00cd9c81dff0700fe3fc6d4cf3bda8637b405a8 100644 (file)
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -809,7 +809,9 @@ void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
   llvm::Function *BeginCatch =
       CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_begincatch);
 
-  if (!CatchParam) {
+  // If this is a catch-all or the catch parameter is unnamed, we don't need to
+  // emit an alloca to the object.
+  if (!CatchParam || !CatchParam->getDeclName()) {
     llvm::Value *Args[2] = {Exn, llvm::Constant::getNullValue(CGF.Int8PtrTy)};
     CGF.EmitNounwindRuntimeCall(BeginCatch, Args);
     CGF.EHStack.pushCleanup<CallEndCatchMSVC>(NormalAndEHCleanup);

diff --git a/clang/test/CodeGenCXX/microsoft-abi-eh-catch.cpp b/clang/test/CodeGenCXX/microsoft-abi-eh-catch.cpp
index 15edef3d1319f2239dbe4ff20909aeabc9f87bf9..292fad2e4d6fee1ad882a3e8c32f90b6596ccccd 100644 (file)
--- a/clang/test/CodeGenCXX/microsoft-abi-eh-catch.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-eh-catch.cpp
@@ -48,6 +48,18 @@ extern "C" void catch_int() {
 // WIN64: call void @handle_exception(i8* %[[e_i8]])
 // WIN64: call void @llvm.eh.endcatch()
 
+extern "C" void catch_int_unnamed() {
+  try {
+    might_throw();
+  } catch (int) {
+  }
+}
+
+// WIN64-LABEL: define void @catch_int_unnamed()
+// WIN64: landingpad { i8*, i32 }
+// WIN64: call void @llvm.eh.begincatch(i8* %{{.*}}, i8* null)
+// WIN64: call void @llvm.eh.endcatch()
+
 struct A {
   A();
   A(const A &o);

diff --git a/clang/test/CodeGenCXX/microsoft-abi-try-throw.cpp b/clang/test/CodeGenCXX/microsoft-abi-try-throw.cpp
index a3a45a5468594fa8c2a010a519895649bd13d503..fed39761714ef18a2c25b1a1e2622346bc6cf87b 100644 (file)
--- a/clang/test/CodeGenCXX/microsoft-abi-try-throw.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-try-throw.cpp
@@ -21,7 +21,7 @@ int main() {
     external(); // TRY: invoke void @"\01?external@@YAXXZ"
   } catch (int) {
     rv = 1;
-    // TRY: call void @llvm.eh.begincatch(i8* %{{.*}}, i8* %{{.*}})
+    // TRY: call void @llvm.eh.begincatch(i8* %{{.*}}, i8* null)
     // TRY: call void @llvm.eh.endcatch()
   }
 #endif