#include "llvm/Function.h"
#include "llvm/Pass.h"
#include "llvm/Type.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
STATISTIC(NumSimplified, "Number of redundant instructions removed");
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
+ AU.addRequired<TargetLibraryInfo>();
}
/// runOnFunction - Remove instructions that simplify.
bool runOnFunction(Function &F) {
- bool Changed = false;
- const TargetData *TD = getAnalysisIfAvailable<TargetData>();
const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
- Instruction *I = BI++;
- if (Value *V = SimplifyInstruction(I, TD, DT)) {
- I->replaceAllUsesWith(V);
- I->eraseFromParent();
- Changed = true;
- ++NumSimplified;
+ const TargetData *TD = getAnalysisIfAvailable<TargetData>();
+ const TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfo>();
+ SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
+ bool Changed = false;
+
+ do {
+ for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
+ DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
+ for (BasicBlock::iterator BI = DI->begin(), BE = DI->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 waste time simplifying unused instructions.
+ if (!I->use_empty())
+ if (Value *V = SimplifyInstruction(I, TD, TLI, DT)) {
+ // 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);
+ ++NumSimplified;
+ Changed = true;
+ }
+ Changed |= RecursivelyDeleteTriviallyDeadInstructions(I);
}
- }
+
+ // Place the list of instructions to simplify on the next loop iteration
+ // into ToSimplify.
+ std::swap(ToSimplify, Next);
+ Next->clear();
+ } while (!ToSimplify->empty());
+
return Changed;
}
};
}
char InstSimplifier::ID = 0;
-INITIALIZE_PASS(InstSimplifier, "instsimplify", "Remove redundant instructions",
- false, false)
+INITIALIZE_PASS_BEGIN(InstSimplifier, "instsimplify",
+ "Remove redundant instructions", false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_END(InstSimplifier, "instsimplify",
+ "Remove redundant instructions", false, false)
char &llvm::InstructionSimplifierID = InstSimplifier::ID;
// Public interface to the simplify instructions pass.