L->getUniqueExitBlocks(ExitBlocks);
array_pod_sort(ExitBlocks.begin(), ExitBlocks.end());
+ SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
+
SmallVector<BasicBlock*, 16> VisitStack;
SmallPtrSet<BasicBlock*, 32> Visited;
// Simplify instructions in the current basic block.
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = BI++;
+
+ // The first time through the loop ToSimplify is empty and we try to
+ // simplify all instructions. On later iterations ToSimplify is not
+ // empty and we only bother simplifying instructions that are in it.
+ if (!ToSimplify->empty() && !ToSimplify->count(I))
+ continue;
+
// Don't bother simplifying unused instructions.
if (!I->use_empty()) {
Value *V = SimplifyInstruction(I, TD, DT);
if (V && LI->replacementPreservesLCSSAForm(I, V)) {
+ // Mark all uses for resimplification next time round the loop.
+ for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
+ UI != UE; ++UI)
+ Next->insert(cast<Instruction>(*UI));
+
I->replaceAllUsesWith(V);
LocalChanged = true;
++NumSimplified;
}
}
+ // Place the list of instructions to simplify on the next loop iteration
+ // into ToSimplify.
+ std::swap(ToSimplify, Next);
+ Next->clear();
+
Changed |= LocalChanged;
} while (LocalChanged);