From 53aac15a607d66926e586c7fc57634f6be4ef443 Mon Sep 17 00:00:00 2001
From: Cameron Zwarich <zwarich@apple.com>
Date: Fri, 11 Mar 2011 21:51:56 +0000
Subject: [PATCH] Fix the GCC test suite issue exposed by r127477, which was
 caused by stack protector insertion not working correctly with unreachable
 code. Since that revision was rolled out, this test doesn't actual fail
 before this fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127497 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/StackProtector.cpp                |  6 +++---
 .../X86/unreachable-stack-protector.ll        | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 test/CodeGen/X86/unreachable-stack-protector.ll

diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp
index fcaee4208ba..02d8fd6dea9 100644
--- a/lib/CodeGen/StackProtector.cpp
+++ b/lib/CodeGen/StackProtector.cpp
@@ -219,8 +219,8 @@ bool StackProtector::InsertStackProtectors() {
 
     // Split the basic block before the return instruction.
     BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return");
-    if (DT) {
-      DT->addNewBlock(NewBB, DT->isReachableFromEntry(BB) ? BB : 0);
+    if (DT && DT->isReachableFromEntry(BB)) {
+      DT->addNewBlock(NewBB, BB);
       FailBBDom = DT->findNearestCommonDominator(FailBBDom, BB);
     }
 
@@ -242,7 +242,7 @@ bool StackProtector::InsertStackProtectors() {
   // statements in the function.
   if (!FailBB) return false;
 
-  if (DT)
+  if (DT && FailBBDom)
     DT->addNewBlock(FailBB, FailBBDom);
 
   return true;
diff --git a/test/CodeGen/X86/unreachable-stack-protector.ll b/test/CodeGen/X86/unreachable-stack-protector.ll
new file mode 100644
index 00000000000..eeebceea71d
--- /dev/null
+++ b/test/CodeGen/X86/unreachable-stack-protector.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0.0"
+
+declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readnone
+
+define void @test5() nounwind optsize noinline ssp {
+entry:
+; CHECK: movq ___stack_chk_guard@GOTPCREL(%rip)
+  %buf = alloca [64 x i8], align 16
+  %0 = call i64 @llvm.objectsize.i64(i8* undef, i1 false)
+  br i1 false, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  unreachable
+
+if.end:                                           ; preds = %entry
+  ret void
+}