[llvm] [SimplifyCFG] Use hash map to continue hoisting the common instructions (PR #78615)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 20 08:35:47 PDT 2024
================
@@ -1635,87 +1675,149 @@ bool SimplifyCFGOpt::hoistCommonCodeFromSuccessors(BasicBlock *BB,
// many instructions we skip, serving as a compilation time control as well as
// preventing excessive increase of life ranges.
unsigned NumSkipped = 0;
- // If we find an unreachable instruction at the beginning of a basic block, we
- // can still hoist instructions from the rest of the basic blocks.
- if (SuccIterPairs.size() > 2) {
- erase_if(SuccIterPairs,
- [](const auto &Pair) { return isa<UnreachableInst>(Pair.first); });
- if (SuccIterPairs.size() < 2)
- return false;
- }
bool Changed = false;
+ auto *SuccIterPairBegin = SuccIterPairs.begin();
+ ++SuccIterPairBegin;
+ auto BBItrPair = *SuccIterPairBegin++;
+ auto OtherSuccIterPairRange =
+ iterator_range(SuccIterPairBegin, SuccIterPairs.end());
+
+ DenseMap<llvm::hash_code, SmallVector<Instruction *, 2>> OtherSuccessorsHash;
+ DenseMap<Instruction *, unsigned> InstToSkipFlag;
+ unsigned skipFlag = 0;
+ Instruction *I = nullptr;
+ do {
+ I = &*BBItrPair.first;
+ auto HashValue = getHash(I);
+ skipFlag |= skippedInstrFlags(I);
+ // For the first successor we created hashmap for, put all instructions
+ // in the hashmap execept for the ones that have the same hash as some
+ // previous instruction in that BB.
+ if (OtherSuccessorsHash.find(HashValue) == OtherSuccessorsHash.end()) {
+ OtherSuccessorsHash[HashValue] = {I};
+ InstToSkipFlag[I] = skipFlag;
+ }
+ BBItrPair.first++;
+ } while (!I->isTerminator());
+
+ unsigned Index = 1;
+ for (auto BBItrPair : OtherSuccIterPairRange) {
+ // Fill the hashmap for every other successor
+ unsigned skipFlag = 0;
+ Instruction *I = nullptr;
+ do {
+ I = &*BBItrPair.first;
+ auto HashValue = getHash(I);
+ skipFlag |= skippedInstrFlags(I);
+ auto &InstVec = OtherSuccessorsHash[HashValue];
+ // For other successors put the instrcution in the map only if there are
+ // instructions with the same hash from other successors and this is the
+ // first instruction with this hash value from current successor.
+ if (OtherSuccessorsHash.find(HashValue) != OtherSuccessorsHash.end() &&
+ InstVec.size() == Index) {
+ InstVec.push_back(I);
+ InstToSkipFlag[I] = skipFlag;
+ }
+ BBItrPair.first++;
+ } while (!I->isTerminator());
+ Index++;
+ }
+
+ // Keep track of instructions skipped in the first successor
+ unsigned SkipFlagsBB1 = 0;
+ bool SameLevelHoist = true;
for (;;) {
auto *SuccIterPairBegin = SuccIterPairs.begin();
auto &BB1ItrPair = *SuccIterPairBegin++;
auto OtherSuccIterPairRange =
iterator_range(SuccIterPairBegin, SuccIterPairs.end());
auto OtherSuccIterRange = make_first_range(OtherSuccIterPairRange);
-
Instruction *I1 = &*BB1ItrPair.first;
// Skip debug info if it is not identical.
- bool AllDbgInstsAreIdentical = all_of(OtherSuccIterRange, [I1](auto &Iter) {
+ bool IdenticalDebugs = all_of(OtherSuccIterRange, [I1](auto &Iter) {
Instruction *I2 = &*Iter;
return I1->isIdenticalToWhenDefined(I2);
});
- if (!AllDbgInstsAreIdentical) {
+ if (!IdenticalDebugs) {
while (isa<DbgInfoIntrinsic>(I1))
I1 = &*++BB1ItrPair.first;
- for (auto &SuccIter : OtherSuccIterRange) {
- Instruction *I2 = &*SuccIter;
- while (isa<DbgInfoIntrinsic>(I2))
- I2 = &*++SuccIter;
- }
}
-
- bool AllInstsAreIdentical = true;
- bool HasTerminator = I1->isTerminator();
- for (auto &SuccIter : OtherSuccIterRange) {
- Instruction *I2 = &*SuccIter;
- HasTerminator |= I2->isTerminator();
- if (AllInstsAreIdentical && !I1->isIdenticalToWhenDefined(I2))
- AllInstsAreIdentical = false;
+ auto OtherInsts = OtherSuccessorsHash[getHash(I1)];
----------------
nikic wrote:
```suggestion
const auto &OtherInsts = OtherSuccessorsHash[getHash(I1)];
```
https://github.com/llvm/llvm-project/pull/78615
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