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Promote partial-loads after stores.

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Swift SVN r14217
This commit is contained in:
Nadav Rotem
2014-02-21 18:41:58 +00:00
parent 0a5f7b57a7
commit 20c8272388
2 changed files with 37 additions and 0 deletions
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19
lib/SILPasses/LoadStoreOpts.cpp
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@@ -144,6 +144,25 @@ bool performLoadStoreOptimizations(SILBasicBlock *BB, AliasAnalysis *AA) {
continue;
}
// Promote partial loads.
// Check that we are loading a struct element:
if (auto *SEAI = dyn_cast<StructElementAddrInst>(LI->getOperand())) {
// And that the previous store stores into that struct.
if (PrevStore && PrevStore->getDest() == SEAI->getOperand()) {
// And that the stored value is a struct construction instruction:
if (auto *SI = dyn_cast<StructInst>(PrevStore->getSrc())) {
DEBUG(llvm::dbgs() << " Forwarding element store from: " <<
*PrevStore);
unsigned FieldNo = SEAI->getFieldNo();
SILValue(LI, 0).replaceAllUsesWith(SI->getOperand(FieldNo));
recursivelyDeleteTriviallyDeadInstructions(LI, true);
Changed = true;
NumForwardedLoads++;
continue;
}
}
}
// Search the previous loads and replace the current load with one of the
// previous loads.
for (auto PrevLI : Loads) {