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[InstSimplify] guard against unreachable code (PR43218) 

This would crash:
https://bugs.llvm.org/show_bug.cgi?id=43218

llvm-svn: 370911
This commit is contained in:
Sanjay Patel 2019-09-04 15:12:55 +00:00
parent 433927595d
commit 4a2cd7be5a
2 changed files with 29 additions and 1 deletions
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7
llvm/lib/Transforms/Scalar/InstSimplifyPass.cpp
View File

@ -34,6 +34,11 @@ static bool runImpl(Function &F, const SimplifyQuery &SQ,
do {
for (BasicBlock &BB : F) {
// Unreachable code can take on strange forms that we are not prepared to
// handle. For example, an instruction may have itself as an operand.
if (!SQ.DT->isReachableFromEntry(&BB))
continue;
SmallVector<Instruction *, 8> DeadInstsInBB;
for (Instruction &I : BB) {
// The first time through the loop, ToSimplify is empty and we try to
@ -87,7 +92,7 @@ struct InstSimplifyLegacyPass : public FunctionPass {
AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
}
/// runOnFunction - Remove instructions that simplify.
/// Remove instructions that simplify.
bool runOnFunction(Function &F) override {
if (skipFunction(F))
return false;

23
llvm/test/Transforms/InstSimplify/insertelement.ll
View File

@ -67,3 +67,26 @@ define <8 x i8> @extract_insert_same_vec_and_index2(<8 x i8> %in, i32 %index) {
%vec = insertelement <8 x i8> %in, i8 %val, i32 %index
ret <8 x i8> %vec
}
; The insert is in an unreachable block, so it is allowed to point to itself.
; This would crash via stack overflow.
define void @PR43218() {
; CHECK-LABEL: @PR43218(
; CHECK-NEXT: end:
; CHECK-NEXT: ret void
; CHECK: unreachable_infloop:
; CHECK-NEXT: [[EXTRACT:%.*]] = extractelement <2 x i64> [[BOGUS:%.*]], i32 0
; CHECK-NEXT: [[T0:%.*]] = inttoptr i64 [[EXTRACT]] to i16****
; CHECK-NEXT: [[BOGUS]] = insertelement <2 x i64> [[BOGUS]], i64 undef, i32 1
; CHECK-NEXT: br label [[UNREACHABLE_INFLOOP:%.*]]
;
end:
ret void
unreachable_infloop:
%extract = extractelement <2 x i64> %bogus, i32 0
%t0 = inttoptr i64 %extract to i16****
%bogus = insertelement <2 x i64> %bogus, i64 undef, i32 1
br label %unreachable_infloop
}