const DominatorTree *DT = 0);
- /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
- /// delete the From instruction. In addition to a basic RAUW, this does a
- /// recursive simplification of the updated instructions. This catches
- /// things where one simplification exposes other opportunities. This only
- /// simplifies and deletes scalar operations, it does not change the CFG.
+ /// \brief Replace all uses of 'I' with 'SimpleV' and simplify the uses
+ /// recursively.
///
- void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
- const TargetData *TD = 0,
- const TargetLibraryInfo *TLI = 0,
- const DominatorTree *DT = 0);
+ /// This first performs a normal RAUW of I with SimpleV. It then recursively
+ /// attempts to simplify those users updated by the operation. The 'I'
+ /// instruction must not be equal to the simplified value 'SimpleV'.
+ ///
+ /// The function returns true if any simplifications were performed.
+ bool replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
+ const TargetData *TD = 0,
+ const TargetLibraryInfo *TLI = 0,
+ const DominatorTree *DT = 0);
+
+ /// \brief Recursively attempt to simplify an instruction.
+ ///
+ /// This routine uses SimplifyInstruction to simplify 'I', and if successful
+ /// replaces uses of 'I' with the simplified value. It then recurses on each
+ /// of the users impacted. It returns true if any simplifications were
+ /// performed.
+ bool recursivelySimplifyInstruction(Instruction *I,
+ const TargetData *TD = 0,
+ const TargetLibraryInfo *TLI = 0,
+ const DominatorTree *DT = 0);
} // end namespace llvm
#endif
return Result == I ? UndefValue::get(I->getType()) : Result;
}
-/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
-/// delete the From instruction. In addition to a basic RAUW, this does a
-/// recursive simplification of the newly formed instructions. This catches
-/// things where one simplification exposes other opportunities. This only
-/// simplifies and deletes scalar operations, it does not change the CFG.
+/// \brief Implementation of recursive simplification through an instructions
+/// uses.
///
-void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
- const TargetData *TD,
- const TargetLibraryInfo *TLI,
- const DominatorTree *DT) {
- assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
-
- // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
- // we can know if it gets deleted out from under us or replaced in a
- // recursive simplification.
- WeakVH FromHandle(From);
- WeakVH ToHandle(To);
-
- while (!From->use_empty()) {
- // Update the instruction to use the new value.
- Use &TheUse = From->use_begin().getUse();
- Instruction *User = cast<Instruction>(TheUse.getUser());
- TheUse = To;
-
- // Check to see if the instruction can be folded due to the operand
- // replacement. For example changing (or X, Y) into (or X, -1) can replace
- // the 'or' with -1.
- Value *SimplifiedVal;
- {
- // Sanity check to make sure 'User' doesn't dangle across
- // SimplifyInstruction.
- AssertingVH<> UserHandle(User);
-
- SimplifiedVal = SimplifyInstruction(User, TD, TLI, DT);
- if (SimplifiedVal == 0) continue;
- }
+/// This is the common implementation of the recursive simplification routines.
+/// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
+/// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
+/// instructions to process and attempt to simplify it using
+/// InstructionSimplify.
+///
+/// This routine returns 'true' only when *it* simplifies something. The passed
+/// in simplified value does not count toward this.
+static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
+ const TargetData *TD,
+ const TargetLibraryInfo *TLI,
+ const DominatorTree *DT) {
+ bool Simplified = false;
+ SmallVector<Instruction *, 8> Worklist;
+
+ // If we have an explicit value to collapse to, do that round of the
+ // simplification loop by hand initially.
+ if (SimpleV) {
+ for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
+ ++UI)
+ Worklist.push_back(cast<Instruction>(*UI));
+
+ // Replace the instruction with its simplified value.
+ I->replaceAllUsesWith(SimpleV);
+
+ // Gracefully handle edge cases where the instruction is not wired into any
+ // parent block.
+ if (I->getParent())
+ I->eraseFromParent();
+ } else {
+ Worklist.push_back(I);
+ }
- // Recursively simplify this user to the new value.
- ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, TLI, DT);
- From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
- To = ToHandle;
+ while (!Worklist.empty()) {
+ I = Worklist.pop_back_val();
- assert(ToHandle && "To value deleted by recursive simplification?");
+ // See if this instruction simplifies.
+ SimpleV = SimplifyInstruction(I, TD, TLI, DT);
+ if (!SimpleV)
+ continue;
+
+ Simplified = true;
+
+ // Stash away all the uses of the old instruction so we can check them for
+ // recursive simplifications after a RAUW. This is cheaper than checking all
+ // uses of To on the recursive step in most cases.
+ for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
+ ++UI)
+ Worklist.push_back(cast<Instruction>(*UI));
- // If the recursive simplification ended up revisiting and deleting
- // 'From' then we're done.
- if (From == 0)
- return;
+ // Replace the instruction with its simplified value.
+ I->replaceAllUsesWith(SimpleV);
+
+ // Gracefully handle edge cases where the instruction is not wired into any
+ // parent block.
+ if (I->getParent())
+ I->eraseFromParent();
}
+ return Simplified;
+}
- // If 'From' has value handles referring to it, do a real RAUW to update them.
- From->replaceAllUsesWith(To);
+bool llvm::recursivelySimplifyInstruction(Instruction *I,
+ const TargetData *TD,
+ const TargetLibraryInfo *TLI,
+ const DominatorTree *DT) {
+ return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT);
+}
- From->eraseFromParent();
+bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
+ const TargetData *TD,
+ const TargetLibraryInfo *TLI,
+ const DominatorTree *DT) {
+ assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
+ assert(SimpleV && "Must provide a simplified value.");
+ return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT);
}
bool MadeChange = false;
for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
Instruction *Inst = BI++;
-
- if (Value *V = SimplifyInstruction(Inst, TD)) {
- WeakVH BIHandle(BI);
- ReplaceAndSimplifyAllUses(Inst, V, TD);
+
+ WeakVH BIHandle(BI);
+ if (recursivelySimplifyInstruction(Inst, TD)) {
MadeChange = true;
if (BIHandle != BI)
BI = BB->begin();
if (Inst->isTerminator())
break;
- WeakVH BIHandle(BI);
MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst);
if (BIHandle != BI)
BI = BB->begin();
WeakVH PhiIt = &BB->front();
while (PHINode *PN = dyn_cast<PHINode>(PhiIt)) {
PhiIt = &*++BasicBlock::iterator(cast<Instruction>(PhiIt));
+ Value *OldPhiIt = PhiIt;
- Value *PNV = SimplifyInstruction(PN, TD);
- if (PNV == 0) continue;
+ if (!recursivelySimplifyInstruction(PN, TD))
+ continue;
- // If we're able to simplify the phi to a single value, substitute the new
- // value into all of its uses.
- assert(PNV != PN && "SimplifyInstruction broken!");
-
- Value *OldPhiIt = PhiIt;
- ReplaceAndSimplifyAllUses(PN, PNV, TD);
-
// If recursive simplification ended up deleting the next PHI node we would
// iterate to, then our iterator is invalid, restart scanning from the top
// of the block.
projects / oota-llvm.git / commitdiff