#include "llvm/Pass.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/CallSite.h"
-#include "llvm/Support/Compiler.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallVector.h"
using namespace llvm;
namespace {
/// IPCP - The interprocedural constant propagation pass
///
- struct VISIBILITY_HIDDEN IPCP : public ModulePass {
+ struct IPCP : public ModulePass {
static char ID; // Pass identification, replacement for typeid
- IPCP() : ModulePass((intptr_t)&ID) {}
+ IPCP() : ModulePass(ID) {
+ initializeIPCPPass(*PassRegistry::getPassRegistry());
+ }
bool runOnModule(Module &M);
private:
}
char IPCP::ID = 0;
-static RegisterPass<IPCP>
-X("ipconstprop", "Interprocedural constant propagation");
+INITIALIZE_PASS(IPCP, "ipconstprop",
+ "Interprocedural constant propagation", false, false)
ModulePass *llvm::createIPConstantPropagationPass() { return new IPCP(); }
if (!I->isDeclaration()) {
// Delete any klingons.
I->removeDeadConstantUsers();
- if (I->hasInternalLinkage())
+ if (I->hasLocalLinkage())
LocalChange |= PropagateConstantsIntoArguments(*I);
Changed |= PropagateConstantReturn(*I);
}
unsigned NumNonconstant = 0;
for (Value::use_iterator UI = F.use_begin(), E = F.use_end(); UI != E; ++UI) {
+ User *U = *UI;
+ // Ignore blockaddress uses.
+ if (isa<BlockAddress>(U)) continue;
+
// Used by a non-instruction, or not the callee of a function, do not
// transform.
- if (UI.getOperandNo() != 0 ||
- (!isa<CallInst>(*UI) && !isa<InvokeInst>(*UI)))
+ if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
return false;
- CallSite CS = CallSite::get(cast<Instruction>(*UI));
+ CallSite CS(cast<Instruction>(U));
+ if (!CS.isCallee(UI))
+ return false;
// Check out all of the potentially constant arguments. Note that we don't
// inspect varargs here.
Function::arg_iterator AI = F.arg_begin();
for (unsigned i = 0, e = ArgumentConstants.size(); i != e; ++i, ++AI) {
// Do we have a constant argument?
- if (ArgumentConstants[i].second || AI->use_empty())
+ if (ArgumentConstants[i].second || AI->use_empty() ||
+ (AI->hasByValAttr() && !F.onlyReadsMemory()))
continue;
Value *V = ArgumentConstants[i].first;
// all callers that use those return values with the constant value. This will
// leave in the actual return values and instructions, but deadargelim will
// clean that up.
+//
+// Additionally if a function always returns one of its arguments directly,
+// callers will be updated to use the value they pass in directly instead of
+// using the return value.
bool IPCP::PropagateConstantReturn(Function &F) {
- if (F.getReturnType() == Type::VoidTy)
+ if (F.getReturnType()->isVoidTy())
return false; // No return value.
// If this function could be overridden later in the link stage, we can't
// propagate information about its results into callers.
- if (F.hasLinkOnceLinkage() || F.hasWeakLinkage())
+ if (F.mayBeOverridden())
return false;
-
+
// Check to see if this function returns a constant.
SmallVector<Value *,4> RetVals;
- const StructType *STy = dyn_cast<StructType>(F.getReturnType());
+ StructType *STy = dyn_cast<StructType>(F.getReturnType());
if (STy)
for (unsigned i = 0, e = STy->getNumElements(); i < e; ++i)
RetVals.push_back(UndefValue::get(STy->getElementType(i)));
unsigned NumNonConstant = 0;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
- // Return type does not match operand type, this is an old style multiple
- // return
- bool OldReturn = (F.getReturnType() != RI->getOperand(0)->getType());
-
for (unsigned i = 0, e = RetVals.size(); i != e; ++i) {
// Already found conflicting return values?
Value *RV = RetVals[i];
// Find the returned value
Value *V;
- if (!STy || OldReturn)
- V = RI->getOperand(i);
+ if (!STy)
+ V = RI->getOperand(0);
else
V = FindInsertedValue(RI->getOperand(0), i);
if (isa<UndefValue>(V))
continue;
- // Try to see if all the rets return the same constant.
- if (isa<Constant>(V)) {
+ // Try to see if all the rets return the same constant or argument.
+ if (isa<Constant>(V) || isa<Argument>(V)) {
if (isa<UndefValue>(RV)) {
// No value found yet? Try the current one.
RetVals[i] = V;
// constant.
bool MadeChange = false;
for (Value::use_iterator UI = F.use_begin(), E = F.use_end(); UI != E; ++UI) {
- // Make sure this is an invoke or call and that the use is for the callee.
- if (!(isa<InvokeInst>(*UI) || isa<CallInst>(*UI)) ||
- UI.getOperandNo() != 0) {
+ CallSite CS(*UI);
+ Instruction* Call = CS.getInstruction();
+
+ // Not a call instruction or a call instruction that's not calling F
+ // directly?
+ if (!Call || !CS.isCallee(UI))
continue;
- }
- Instruction *Call = cast<Instruction>(*UI);
+ // Call result not used?
if (Call->use_empty())
continue;
MadeChange = true;
if (STy == 0) {
- Call->replaceAllUsesWith(RetVals[0]);
+ Value* New = RetVals[0];
+ if (Argument *A = dyn_cast<Argument>(New))
+ // Was an argument returned? Then find the corresponding argument in
+ // the call instruction and use that.
+ New = CS.getArgument(A->getArgNo());
+ Call->replaceAllUsesWith(New);
continue;
}
for (Value::use_iterator I = Call->use_begin(), E = Call->use_end();
I != E;) {
- Instruction *Ins = dyn_cast<Instruction>(*I);
+ Instruction *Ins = cast<Instruction>(*I);
// Increment now, so we can remove the use
++I;
- // Not an instruction? Ignore
- if (!Ins)
- continue;
-
// Find the index of the retval to replace with
int index = -1;
- if (GetResultInst *GR = dyn_cast<GetResultInst>(Ins))
- index = GR->getIndex();
- else if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Ins))
+ if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Ins))
if (EV->hasIndices())
index = *EV->idx_begin();
if (index != -1) {
Value *New = RetVals[index];
if (New) {
+ if (Argument *A = dyn_cast<Argument>(New))
+ // Was an argument returned? Then find the corresponding argument in
+ // the call instruction and use that.
+ New = CS.getArgument(A->getArgNo());
Ins->replaceAllUsesWith(New);
Ins->eraseFromParent();
}
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