[llvm] r267767 - [CodeGenPrepare] Don't sink a cast past its user

[David Majnemer via llvm-commits]

Author: majnemer
Date: Wed Apr 27 14:36:38 2016
New Revision: 267767

URL: http://llvm.org/viewvc/llvm-project?rev=267767&view=rev
Log:
[CodeGenPrepare] Don't sink a cast past its user

The sink cast machinery is supposed to sink casts as close to their user
as possible.  However, an EH pad is the first instruction in it's basic
block.  Don't sink if the user is an EH pad.

This fixes PR27536.

Added:
    llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr27536.ll
Modified:
    llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp

Modified: llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp?rev=267767&r1=267766&r2=267767&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp Wed Apr 27 14:36:38 2016
@@ -758,6 +758,11 @@ static bool SinkCast(CastInst *CI) {
     // Preincrement use iterator so we don't invalidate it.
     ++UI;
 
+    // The first insertion point of a block containing an EH pad is after the
+    // pad.  If the pad is the user, we cannot sink the cast past the pad.
+    if (User->isEHPad())
+      continue;
+
     // 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.

Added: llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr27536.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr27536.ll?rev=267767&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr27536.ll (added)
+++ llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr27536.ll Wed Apr 27 14:36:38 2016
@@ -0,0 +1,32 @@
+; RUN: opt -S -codegenprepare < %s | FileCheck %s
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+ at rtti = external global i8
+
+define void @test1() personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+  %e = alloca i8
+  %tmpcast = bitcast i8* %e to i16*
+  invoke void @_CxxThrowException(i8* null, i8* null)
+          to label %catchret.dest unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %0 = catchswitch within none [label %catch] unwind to caller
+
+catch:                                            ; preds = %catch.dispatch
+  %1 = catchpad within %0 [i8* @rtti, i32 0, i16* %tmpcast]
+  catchret from %1 to label %catchret.dest
+
+catchret.dest:                                    ; preds = %catch
+  ret void
+}
+; CHECK-LABEL: define void @test1(
+; CHECK: %[[alloca:.*]] = alloca i8
+; CHECK-NEXT: %[[bc:.*]] = bitcast i8* %[[alloca]] to i16*
+
+; CHECK: catchpad within {{.*}} [i8* @rtti, i32 0, i16* %[[bc]]]
+
+declare void @_CxxThrowException(i8*, i8*)
+
+declare i32 @__CxxFrameHandler3(...)