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.

llvm-svn: 127497

2 files changed, 22 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
index fcaee4208ba..02d8fd6dea9 100644
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/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/llvm/test/CodeGen/X86/unreachable-stack-protector.ll b/llvm/test/CodeGen/X86/unreachable-stack-protector.ll
new file mode 100644
index 00000000000..eeebceea71d
--- /dev/null
+++ b/llvm/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
+}