Fix llc to not reuse spill slots in functions that invoke setjmp()

We need to ensure that StackSlotColoring.cpp does not reuse stack
spill slots in functions that call "returns_twice" functions such as
setjmp(), otherwise this can lead to miscompiled code, because a stack
slot would be clobbered when it's still live.

This was already handled correctly for functions that call setjmp()
(though this wasn't covered by a test), but not for functions that
invoke setjmp().

We fix this by changing callsFunctionThatReturnsTwice() to check for
invoke instructions.

This fixes PR18244.

llvm-svn: 199180

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 970bbae..bb6bef7 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -736,10 +736,8 @@ bool Function::isDefTriviallyDead() const {
 bool Function::callsFunctionThatReturnsTwice() const {
   for (const_inst_iterator
          I = inst_begin(this), E = inst_end(this); I != E; ++I) {
-    const CallInst* callInst = dyn_cast<CallInst>(&*I);
-    if (!callInst)
-      continue;
-    if (callInst->canReturnTwice())
+    ImmutableCallSite CS(&*I);
+    if (CS && CS.hasFnAttr(Attribute::ReturnsTwice))
       return true;
   }