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Add a simple call constant propagation interface.

llvm-svn: 12919
This commit is contained in:
Chris Lattner 2004-04-13 19:28:52 +00:00
parent 2bf8038c69
commit 778f09027f

View File

@ -57,6 +57,18 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I) {
// If we reach here, all incoming values are the same constant.
return Result;
} else if (CallInst *CI = dyn_cast<CallInst>(I)) {
if (Function *F = CI->getCalledFunction())
if (canConstantFoldCallTo(F)) {
std::vector<Constant*> Args;
for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
if (Constant *Op = dyn_cast<Constant>(CI->getOperand(i)))
Args.push_back(Op);
else
return 0;
return ConstantFoldCall(F, Args);
}
return 0;
}
Constant *Op0 = 0, *Op1 = 0;
@ -216,6 +228,45 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
return false;
}
/// canConstantFoldCallTo - Return true if its even possible to fold a call to
/// the specified function.
bool llvm::canConstantFoldCallTo(Function *F) {
const std::string &Name = F->getName();
return Name == "sin" || Name == "cos" || Name == "tan" || Name == "sqrt";
}
/// ConstantFoldCall - Attempt to constant fold a call to the specified function
/// with the specified arguments, returning null if unsuccessful.
Constant *llvm::ConstantFoldCall(Function *F,
const std::vector<Constant*> &Operands) {
const std::string &Name = F->getName();
const Type *Ty = F->getReturnType();
if (Name == "sin") {
if (Operands.size() == 1)
if (ConstantFP *CFP = dyn_cast<ConstantFP>(Operands[0]))
return ConstantFP::get(Ty, sin(CFP->getValue()));
} else if (Name == "cos") {
if (Operands.size() == 1)
if (ConstantFP *CFP = dyn_cast<ConstantFP>(Operands[0]))
return ConstantFP::get(Ty, cos(CFP->getValue()));
} else if (Name == "tan") {
if (Operands.size() == 1)
if (ConstantFP *CFP = dyn_cast<ConstantFP>(Operands[0]))
return ConstantFP::get(Ty, tan(CFP->getValue()));
} else if (Name == "sqrt") {
if (Operands.size() == 1)
if (ConstantFP *CFP = dyn_cast<ConstantFP>(Operands[0]))
if (CFP->getValue() >= 0)
return ConstantFP::get(Ty, sqrt(CFP->getValue()));
}
return 0;
}
//===----------------------------------------------------------------------===//