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Implement a few missing xforms: printf("foo\n") -> puts. printf("x") -> putchar 

printf("") -> noop.  Still need to do the xforms for fprintf.

This implements Transforms/SimplifyLibCalls/Printf.ll

llvm-svn: 35984
This commit is contained in:
Chris Lattner 2007-04-14 01:17:48 +00:00
parent ebf3cfccdb
commit 49fa8d2bff
1 changed files with 48 additions and 9 deletions
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57
llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp
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@ -1154,22 +1154,61 @@ public:
/// @brief Make sure that the "printf" function has the right prototype
virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
// Just make sure this has at least 1 arguments
return F->arg_size() >= 1;
// Just make sure this has at least 1 argument and returns an integer or
// void type.
const FunctionType *FT = F->getFunctionType();
return FT->getNumParams() >= 1 &&
(isa<IntegerType>(FT->getReturnType()) ||
FT->getReturnType() == Type::VoidTy);
}
/// @brief Perform the printf optimization.
virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
// If the call has more than 2 operands, we can't optimize it
if (CI->getNumOperands() != 3)
return false;
// All the optimizations depend on the length of the first argument and the
// fact that it is a constant string array. Check that now
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
return false;
// If this is a simple constant string with no format specifiers that ends
// with a \n, turn it into a puts call.
if (FormatStr.empty()) {
// Tolerate printf's declared void.
if (CI->use_empty()) return ReplaceCallWith(CI, 0);
return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 0));
}
if (FormatStr.size() == 1) {
// Turn this into a putchar call, even if it is a %.
Value *V = ConstantInt::get(Type::Int32Ty, FormatStr[0]);
new CallInst(SLC.get_putchar(), V, "", CI);
if (CI->use_empty()) return ReplaceCallWith(CI, 0);
return ReplaceCallWith(CI, ConstantInt::get(CI->getType(), 1));
}
// Check to see if the format str is something like "foo\n", in which case
// we convert it to a puts call. We don't allow it to contain any format
// characters.
if (FormatStr[FormatStr.size()-1] == '\n' &&
FormatStr.find('%') == std::string::npos) {
// Create a string literal with no \n on it. We expect the constant merge
// pass to be run after this pass, to merge duplicate strings.
FormatStr.erase(FormatStr.end()-1);
Constant *Init = ConstantArray::get(FormatStr, true);
Constant *GV = new GlobalVariable(Init->getType(), true,
GlobalVariable::InternalLinkage,
Init, "str",
CI->getParent()->getParent()->getParent());
// Cast GV to be a pointer to char.
GV = ConstantExpr::getBitCast(GV, PointerType::get(Type::Int8Ty));
new CallInst(SLC.get_puts(), GV, "", CI);
if (CI->use_empty()) return ReplaceCallWith(CI, 0);
return ReplaceCallWith(CI,
ConstantInt::get(CI->getType(), FormatStr.size()));
}
// Only support %c or "%s\n" for now.
if (FormatStr.size() < 2 || FormatStr[0] != '%')
return false;
@ -1178,7 +1217,7 @@ public:
switch (FormatStr[1]) {
default: return false;
case 's':
if (FormatStr != "%s\n" ||
if (FormatStr != "%s\n" || CI->getNumOperands() < 3 ||
// TODO: could insert strlen call to compute string length.
!CI->use_empty())
return false;
@ -1189,7 +1228,7 @@ public:
return ReplaceCallWith(CI, 0);
case 'c': {
// printf("%c",c) -> putchar(c)
if (FormatStr.size() != 2)
if (FormatStr.size() != 2 || CI->getNumOperands() < 3)
return false;
Value *V = CI->getOperand(2);
@ -1917,7 +1956,7 @@ static Value *CastToCStr(Value *V, Instruction *IP) {
// * pow(pow(x,y),z)-> pow(x,y*z)
//
// puts:
// * puts("") -> fputc("\n",stdout) (how do we get "stdout"?)
// * puts("") -> putchar("\n")
//
// round, roundf, roundl:
// * round(cnst) -> cnst'