instcombine: Migrate sprintf optimizations
This patch migrates the sprintf optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168677 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 2e494fd..96f09d2 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1409,6 +1409,99 @@
}
};
+struct SPrintFOpt : public LibCallOptimization {
+ Value *OptimizeFixedFormatString(Function *Callee, CallInst *CI,
+ IRBuilder<> &B) {
+ // Check for a fixed format string.
+ StringRef FormatStr;
+ if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
+ return 0;
+
+ // If we just have a format string (nothing else crazy) transform it.
+ if (CI->getNumArgOperands() == 2) {
+ // Make sure there's no % in the constant array. We could try to handle
+ // %% -> % in the future if we cared.
+ for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
+ if (FormatStr[i] == '%')
+ return 0; // we found a format specifier, bail out.
+
+ // These optimizations require DataLayout.
+ if (!TD) return 0;
+
+ // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
+ B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
+ ConstantInt::get(TD->getIntPtrType(*Context), // Copy the
+ FormatStr.size() + 1), 1); // nul byte.
+ return ConstantInt::get(CI->getType(), FormatStr.size());
+ }
+
+ // The remaining optimizations require the format string to be "%s" or "%c"
+ // and have an extra operand.
+ if (FormatStr.size() != 2 || FormatStr[0] != '%' ||
+ CI->getNumArgOperands() < 3)
+ return 0;
+
+ // Decode the second character of the format string.
+ if (FormatStr[1] == 'c') {
+ // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
+ if (!CI->getArgOperand(2)->getType()->isIntegerTy()) return 0;
+ Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char");
+ Value *Ptr = CastToCStr(CI->getArgOperand(0), B);
+ B.CreateStore(V, Ptr);
+ Ptr = B.CreateGEP(Ptr, B.getInt32(1), "nul");
+ B.CreateStore(B.getInt8(0), Ptr);
+
+ return ConstantInt::get(CI->getType(), 1);
+ }
+
+ if (FormatStr[1] == 's') {
+ // These optimizations require DataLayout.
+ if (!TD) return 0;
+
+ // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
+ if (!CI->getArgOperand(2)->getType()->isPointerTy()) return 0;
+
+ Value *Len = EmitStrLen(CI->getArgOperand(2), B, TD, TLI);
+ if (!Len)
+ return 0;
+ Value *IncLen = B.CreateAdd(Len,
+ ConstantInt::get(Len->getType(), 1),
+ "leninc");
+ B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(2), IncLen, 1);
+
+ // The sprintf result is the unincremented number of bytes in the string.
+ return B.CreateIntCast(Len, CI->getType(), false);
+ }
+ return 0;
+ }
+
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ // Require two fixed pointer arguments and an integer result.
+ FunctionType *FT = Callee->getFunctionType();
+ if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() ||
+ !FT->getParamType(1)->isPointerTy() ||
+ !FT->getReturnType()->isIntegerTy())
+ return 0;
+
+ if (Value *V = OptimizeFixedFormatString(Callee, CI, B)) {
+ return V;
+ }
+
+ // sprintf(str, format, ...) -> siprintf(str, format, ...) if no floating
+ // point arguments.
+ if (TLI->has(LibFunc::siprintf) && !callHasFloatingPointArgument(CI)) {
+ Module *M = B.GetInsertBlock()->getParent()->getParent();
+ Constant *SIPrintFFn =
+ M->getOrInsertFunction("siprintf", FT, Callee->getAttributes());
+ CallInst *New = cast<CallInst>(CI->clone());
+ New->setCalledFunction(SIPrintFFn);
+ B.Insert(New);
+ return New;
+ }
+ return 0;
+ }
+};
+
} // End anonymous namespace.
namespace llvm {
@@ -1464,6 +1557,7 @@
// Formatting and IO library call optimizations.
PrintFOpt PrintF;
+ SPrintFOpt SPrintF;
void initOptimizations();
void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1588,6 +1682,7 @@
// Formatting and IO library call optimizations.
addOpt(LibFunc::printf, &PrintF);
+ addOpt(LibFunc::sprintf, &SPrintF);
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {