diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/EarlyCSE.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/EarlyCSE.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp index 6376aae5cbd..0a8a7508c19 100644 --- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp +++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp @@ -562,6 +562,19 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { continue; } + // Skip invariant.start intrinsics since they only read memory, and we can + // forward values across it. Also, we dont need to consume the last store + // since the semantics of invariant.start allow us to perform DSE of the + // last store, if there was a store following invariant.start. Consider: + // + // store 30, i8* p + // invariant.start(p) + // store 40, i8* p + // We can DSE the store to 30, since the store 40 to invariant location p + // causes undefined behaviour. + if (match(Inst, m_Intrinsic<Intrinsic::invariant_start>())) + continue; + if (match(Inst, m_Intrinsic<Intrinsic::experimental_guard>())) { if (auto *CondI = dyn_cast<Instruction>(cast<CallInst>(Inst)->getArgOperand(0))) { |
