r249616 - [WinEH] Don't use lifetime markers for MS catch parameters

[Reid Kleckner via cfe-commits]

Author: rnk
Date: Wed Oct  7 16:03:41 2015
New Revision: 249616

URL: http://llvm.org/viewvc/llvm-project?rev=249616&view=rev
Log:
[WinEH] Don't use lifetime markers for MS catch parameters

We don't have a good place to put them. Our previous spot was causing us
to optimize loads from the exception object to undef, because it was
after the catchpad instruction that models the write to the catch
object.

Modified:
    cfe/trunk/lib/CodeGen/CGDecl.cpp
    cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-catch.cpp

Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=249616&r1=249615&r2=249616&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Wed Oct  7 16:03:41 2015
@@ -974,9 +974,15 @@ CodeGenFunction::EmitAutoVarAlloca(const
       address = CreateTempAlloca(allocaTy, allocaAlignment);
       address.getPointer()->setName(D.getName());
 
+      // Don't emit lifetime markers for MSVC catch parameters. The lifetime of
+      // the catch parameter starts in the catchpad instruction, and we can't
+      // insert code in those basic blocks.
+      bool IsMSCatchParam =
+          D.isExceptionVariable() && getTarget().getCXXABI().isMicrosoft();
+
       // Emit a lifetime intrinsic if meaningful.  There's no point
       // in doing this if we don't have a valid insertion point (?).
-      if (HaveInsertPoint()) {
+      if (HaveInsertPoint() && !IsMSCatchParam) {
         uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
         emission.SizeForLifetimeMarkers =
           EmitLifetimeStart(size, address.getPointer());

Modified: cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-catch.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-catch.cpp?rev=249616&r1=249615&r2=249616&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-catch.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/microsoft-abi-eh-catch.cpp Wed Oct  7 16:03:41 2015
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-pc-windows-msvc \
 // RUN:     -mconstructor-aliases -fexceptions -fcxx-exceptions -fnew-ms-eh \
+// RUN:     -O1 -disable-llvm-optzns \
 // RUN:     | FileCheck -check-prefix WIN64 %s
 
 extern "C" void might_throw();
@@ -47,8 +48,17 @@ extern "C" void catch_int() {
 
 // WIN64-LABEL: define void @catch_int()
 // WIN64: catchpad [%rtti.TypeDescriptor2* @"\01??_R0H at 8", i32 0, i32* %[[e_addr:[^\]]*]]]
+//
+// The catchpad instruction starts the lifetime of 'e'. Unfortunately, that
+// leaves us with nowhere to put lifetime.start, so we don't emit lifetime
+// markers for now.
+// WIN64-NOT: lifetime.start
+//
 // WIN64: %[[e_i8:[^ ]*]] = bitcast i32* %[[e_addr]] to i8*
-// WIN64: call void @handle_exception(i8* %[[e_i8]])
+// WIN64-NOT: lifetime.start
+// WIN64: call void @handle_exception
+// WIN64-SAME: (i8* %[[e_i8]])
+// WIN64-NOT: lifetime.end
 // WIN64: catchret
 
 extern "C" void catch_int_unnamed() {