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Use a worklist for later iterations just like ordinary instsimplify. The next

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step is to only process instructions in subloops if they have been modified by
an earlier simplification.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122869 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich
2011-01-05 05:47:47 +00:00
parent e389ab16f3
commit 08602ab1b4
1 changed files with 19 additions and 0 deletions
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19
lib/Transforms/Scalar/LoopInstSimplify.cpp
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@ -66,6 +66,8 @@ bool LoopInstSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
L->getUniqueExitBlocks(ExitBlocks); L->getUniqueExitBlocks(ExitBlocks);
array_pod_sort(ExitBlocks.begin(), ExitBlocks.end()); array_pod_sort(ExitBlocks.begin(), ExitBlocks.end());
SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
SmallVector<BasicBlock*, 16> VisitStack; SmallVector<BasicBlock*, 16> VisitStack;
SmallPtrSet<BasicBlock*, 32> Visited; SmallPtrSet<BasicBlock*, 32> Visited;
@ -86,10 +88,22 @@ bool LoopInstSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
// Simplify instructions in the current basic block. // Simplify instructions in the current basic block.
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) { for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = BI++; 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. // Don't bother simplifying unused instructions.
if (!I->use_empty()) { if (!I->use_empty()) {
Value *V = SimplifyInstruction(I, TD, DT); Value *V = SimplifyInstruction(I, TD, DT);
if (V && LI->replacementPreservesLCSSAForm(I, V)) { 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); I->replaceAllUsesWith(V);
LocalChanged = true; LocalChanged = true;
++NumSimplified; ++NumSimplified;
@ -109,6 +123,11 @@ bool LoopInstSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
} }
} }
// Place the list of instructions to simplify on the next loop iteration
// into ToSimplify.
std::swap(ToSimplify, Next);
Next->clear();
Changed |= LocalChanged; Changed |= LocalChanged;
} while (LocalChanged); } while (LocalChanged);