[Module] Disable lifting for inline asm resembling memory fences with return values

Inline asm used for memory barriers might use their operands and propagate them as
return value.

This is currently not supported. Tighten check for this condition and do not to
lift those inline asm instructions.

Fixes #1252

1 files changed, 6 insertions, 4 deletions

diff --git a/lib/Module/RaiseAsm.cpp b/lib/Module/RaiseAsm.cpp
index acb7d0cf..3de28f4d 100644
--- a/lib/Module/RaiseAsm.cpp
+++ b/lib/Module/RaiseAsm.cpp
@@ -10,14 +10,15 @@
 #include "Passes.h"
 #include "klee/Config/Version.h"
 #include "klee/Support/ErrorHandling.h"
+
+#include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InlineAsm.h"
-#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Instructions.h"
-
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/raw_ostream.h"
 #if LLVM_VERSION_CODE >= LLVM_VERSION(6, 0)
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
@@ -63,7 +64,8 @@ bool RaiseAsmPass::runOnInstruction(Module &M, Instruction *I) {
        triple.getOS() == llvm::Triple::Darwin ||
        triple.getOS() == llvm::Triple::FreeBSD)) {
 
-    if (ia->getAsmString() == "" && ia->hasSideEffects()) {
+    if (ia->getAsmString() == "" && ia->hasSideEffects() &&
+        ia->getFunctionType()->getReturnType()->isVoidTy()) {
       IRBuilder<> Builder(I);
 #if LLVM_VERSION_CODE >= LLVM_VERSION(3, 9)
       Builder.CreateFence(llvm::AtomicOrdering::SequentiallyConsistent);