diff options
Diffstat (limited to 'lib/Transforms/Utils/SimplifyLibCalls.cpp')
-rw-r--r-- | lib/Transforms/Utils/SimplifyLibCalls.cpp | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp index cceec66..dd623dc 100644 --- a/lib/Transforms/Utils/SimplifyLibCalls.cpp +++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp @@ -20,6 +20,7 @@ #include "llvm/Analysis/ValueTracking.h" #include "llvm/Function.h" #include "llvm/IRBuilder.h" +#include "llvm/Intrinsics.h" #include "llvm/Module.h" #include "llvm/LLVMContext.h" #include "llvm/Target/TargetLibraryInfo.h" @@ -1212,6 +1213,43 @@ struct Exp2Opt : public UnsafeFPLibCallOptimization { } }; +//===----------------------------------------------------------------------===// +// Integer Library Call Optimizations +//===----------------------------------------------------------------------===// + +struct FFSOpt : public LibCallOptimization { + virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) { + FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 2 arguments of the same FP type, which match the + // result type. + if (FT->getNumParams() != 1 || + !FT->getReturnType()->isIntegerTy(32) || + !FT->getParamType(0)->isIntegerTy()) + return 0; + + Value *Op = CI->getArgOperand(0); + + // Constant fold. + if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) { + if (CI->isZero()) // ffs(0) -> 0. + return B.getInt32(0); + // ffs(c) -> cttz(c)+1 + return B.getInt32(CI->getValue().countTrailingZeros() + 1); + } + + // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0 + Type *ArgType = Op->getType(); + Value *F = Intrinsic::getDeclaration(Callee->getParent(), + Intrinsic::cttz, ArgType); + Value *V = B.CreateCall2(F, Op, B.getFalse(), "cttz"); + V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1)); + V = B.CreateIntCast(V, B.getInt32Ty(), false); + + Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType)); + return B.CreateSelect(Cond, V, B.getInt32(0)); + } +}; + } // End anonymous namespace. namespace llvm { @@ -1258,6 +1296,9 @@ class LibCallSimplifierImpl { UnaryDoubleFPOpt UnaryDoubleFP, UnsafeUnaryDoubleFP; CosOpt Cos; PowOpt Pow; Exp2Opt Exp2; + // Integer library call optimizations. + FFSOpt FFS; + void initOptimizations(); void addOpt(LibFunc::Func F, LibCallOptimization* Opt); void addOpt(LibFunc::Func F1, LibFunc::Func F2, LibCallOptimization* Opt); @@ -1367,6 +1408,11 @@ void LibCallSimplifierImpl::initOptimizations() { Optimizations["llvm.exp2.f80"] = &Exp2; Optimizations["llvm.exp2.f64"] = &Exp2; Optimizations["llvm.exp2.f32"] = &Exp2; + + // Integer library call optimizations. + addOpt(LibFunc::ffs, &FFS); + addOpt(LibFunc::ffsl, &FFS); + addOpt(LibFunc::ffsll, &FFS); } Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) { |