/// ChangeToUnreachable - Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
-static void ChangeToUnreachable(Instruction *I) {
+static void ChangeToUnreachable(Instruction *I, bool UseLLVMTrap) {
BasicBlock *BB = I->getParent();
// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
(*SI)->removePredecessor(BB);
+ // Insert a call to llvm.trap right before this. This turns the undefined
+ // behavior into a hard fail instead of falling through into random code.
+ if (UseLLVMTrap) {
+ Function *TrapFn =
+ Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
+ CallInst::Create(TrapFn, "", I);
+ }
new UnreachableInst(I->getContext(), I);
// All instructions after this are dead.
// though.
++BBI;
if (!isa<UnreachableInst>(BBI)) {
- ChangeToUnreachable(BBI);
+ // Don't insert a call to llvm.trap right before the unreachable.
+ ChangeToUnreachable(BBI, false);
Changed = true;
}
break;
if (isa<UndefValue>(Ptr) ||
(isa<ConstantPointerNull>(Ptr) &&
SI->getPointerAddressSpace() == 0)) {
- ChangeToUnreachable(SI);
+ ChangeToUnreachable(SI, true);
Changed = true;
break;
}
-; RUN: opt < %s -simplifycfg -S | grep {volatile load}
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
; PR2967
target datalayout =
"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32"
target triple = "i386-pc-linux-gnu"
-define void @foo(i32 %x) nounwind {
+define void @test1(i32 %x) nounwind {
entry:
%0 = icmp eq i32 %x, 0 ; <i1> [#uses=1]
br i1 %0, label %bb, label %return
bb: ; preds = %entry
- %1 = volatile load i32* null ; <i32> [#uses=0]
+ %1 = volatile load i32* null
unreachable
+
br label %return
return: ; preds = %entry
ret void
+; CHECK: @test1
+; CHECK: volatile load
+}
+
+; rdar://7958343
+define void @test2() nounwind {
+entry:
+ store i32 4,i32* null
+ ret void
+
+; CHECK: @test2
+; CHECK: call void @llvm.trap
+; CHECK: unreachable
}