instcombine: Migrate *abs optimizations
This patch migrates the *abs optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168574 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index dd623dc..ec98e93 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1250,6 +1250,23 @@
}
};
+struct AbsOpt : public LibCallOptimization {
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ FunctionType *FT = Callee->getFunctionType();
+ // We require integer(integer) where the types agree.
+ if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
+ FT->getParamType(0) != FT->getReturnType())
+ return 0;
+
+ // abs(x) -> x >s -1 ? x : -x
+ Value *Op = CI->getArgOperand(0);
+ Value *Pos = B.CreateICmpSGT(Op, Constant::getAllOnesValue(Op->getType()),
+ "ispos");
+ Value *Neg = B.CreateNeg(Op, "neg");
+ return B.CreateSelect(Pos, Op, Neg);
+ }
+};
+
} // End anonymous namespace.
namespace llvm {
@@ -1298,6 +1315,7 @@
// Integer library call optimizations.
FFSOpt FFS;
+ AbsOpt Abs;
void initOptimizations();
void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1413,6 +1431,9 @@
addOpt(LibFunc::ffs, &FFS);
addOpt(LibFunc::ffsl, &FFS);
addOpt(LibFunc::ffsll, &FFS);
+ addOpt(LibFunc::abs, &Abs);
+ addOpt(LibFunc::labs, &Abs);
+ addOpt(LibFunc::llabs, &Abs);
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {