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[GVNHoist] Prune out useless CHI insertions 

Fix for the out-of-memory error when compiling SemaChecking.cpp
with GVNHoist and ubsan enabled. I've used a cache for inserted
CHIs to avoid excessive memory usage.

Differential Revision: https://reviews.llvm.org/D50323

llvm-svn: 340818
This commit is contained in:
Alexandros Lamprineas 2018-08-28 11:07:54 +00:00
parent 99fc18c387
commit 484bd13e2d
1 changed files with 5 additions and 2 deletions
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7
llvm/lib/Transforms/Scalar/GVNHoist.cpp
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@ -155,6 +155,7 @@ struct CHIArg {
using CHIIt = SmallVectorImpl<CHIArg>::iterator;
using CHIArgs = iterator_range<CHIIt>;
using CHICache = DenseMap<BasicBlock *, SmallPtrSet<Instruction *, 4>>;
using OutValuesType = DenseMap<BasicBlock *, SmallVector<CHIArg, 2>>;
using InValuesType =
DenseMap<BasicBlock *, SmallVector<std::pair<VNType, Instruction *>, 2>>;
@ -766,6 +767,7 @@ private:
ReverseIDFCalculator IDFs(*PDT);
OutValuesType OutValue;
InValuesType InValue;
CHICache CachedCHIs;
for (const auto &R : Ranks) {
const SmallVecInsn &V = Map.lookup(R);
if (V.size() < 2)
@ -792,11 +794,12 @@ private:
}
// Insert empty CHI node for this VN. This is used to factor out
// basic blocks where the ANTIC can potentially change.
for (auto IDFB : IDFBlocks) { // TODO: Prune out useless CHI insertions.
for (auto IDFB : IDFBlocks) {
for (unsigned i = 0; i < V.size(); ++i) {
CHIArg C = {VN, nullptr, nullptr};
// Ignore spurious PDFs.
if (DT->properlyDominates(IDFB, V[i]->getParent())) {
if (DT->properlyDominates(IDFB, V[i]->getParent()) &&
CachedCHIs[IDFB].insert(V[i]).second) {
OutValue[IDFB].push_back(C);
LLVM_DEBUG(dbgs() << "\nInsertion a CHI for BB: " << IDFB->getName()
<< ", for Insn: " << *V[i]);