From 0c80e2eac64d6f25e522079632de8bf4d201b459 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Wed, 27 Apr 2016 19:36:38 +0000
Subject: [PATCH] [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.

llvm-svn: 267767
---
 llvm/lib/CodeGen/CodeGenPrepare.cpp                |  5 ++++
 llvm/test/Transforms/CodeGenPrepare/X86/pr27536.ll | 32 ++++++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 llvm/test/Transforms/CodeGenPrepare/X86/pr27536.ll

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 3adad3b..b5ffbeb 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -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.
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/pr27536.ll b/llvm/test/Transforms/CodeGenPrepare/X86/pr27536.ll
new file mode 100644
index 0000000..7ab1b03
--- /dev/null
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/pr27536.ll
@@ -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"
+
+@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(...)
-- 
2.7.4