[WinEH] Fix problem where CodeGenPrepare incorrectly sinks a bitcast into an EH pad.

Differential Revision: http://reviews.llvm.org/D14842

llvm-svn: 253902

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -730,6 +730,12 @@ static bool SinkCast(CastInst *CI) {
     // Preincrement use iterator so we don't invalidate it.
     ++UI;
 
+    // If the block selected to receive the cast is an EH pad that does not
+    // allow non-PHI instructions before the terminator, we can't sink the
+    // cast.
+    if (UserBB->getTerminator()->isEHPad())
+      continue;
+
     // If this user is in the same block as the cast, don't change the cast.
     if (UserBB == DefBB) continue;
 

llvm/test/Transforms/CodeGenPrepare/catchpad-phi-cast.ll

@@ -0,0 +1,59 @@
+; RUN: opt -codegenprepare -S < %s | FileCheck %s
+
+; The following target lines are needed for the test to exercise what it should.
+; Without these lines, CodeGenPrepare does not try to sink the bitcasts.
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+declare i32 @__CxxFrameHandler3(...)
+
+declare void @f()
+
+declare void @g(i8*)
+
+; CodeGenPrepare will want to sink these bitcasts, but it selects the catchpad
+; blocks as the place to which the bitcast should be sunk.  Since catchpads
+; do not allow non-phi instructions before the terminator, this isn't possible. 
+
+; CHECK-LABEL: @test(
+define void @test(i32* %addr) personality i32 (...)* @__CxxFrameHandler3 {
+; CHECK: entry:
+; CHECK-NEXT: %x = getelementptr i32, i32* %addr, i32 1
+; CHECK-NEXT: %p1 = bitcast i32* %x to i8*
+entry:
+  %x = getelementptr i32, i32* %addr, i32 1
+  %p1 = bitcast i32* %x to i8*
+  invoke void @f()
+          to label %invoke.cont unwind label %catch1
+
+; CHECK: invoke.cont:
+; CHECK-NEXT: %y = getelementptr i32, i32* %addr, i32 2
+; CHECK-NEXT: %p2 = bitcast i32* %y to i8*
+invoke.cont:
+  %y = getelementptr i32, i32* %addr, i32 2
+  %p2 = bitcast i32* %y to i8*
+  invoke void @f()
+          to label %done unwind label %catch2
+
+done:
+  ret void
+
+catch1:
+  %cp1 = catchpad [] to label %catch.dispatch unwind label %catchend1
+
+catch2:
+  %cp2 = catchpad [] to label %catch.dispatch unwind label %catchend2
+
+; CHECK: catch.dispatch:
+; CHECK-NEXT: %p = phi i8* [ %p1, %catch1 ], [ %p2, %catch2 ]
+catch.dispatch:
+  %p = phi i8* [ %p1, %catch1 ], [ %p2, %catch2 ]
+  call void @g(i8* %p)
+  unreachable
+
+catchend1:
+  catchendpad unwind to caller
+
+catchend2:
+  catchendpad unwind to caller
+}