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[SimplifyLibCalls] Constant fold fdim
Signed-off-by: Kushal Pal <[email protected]>
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‎llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h

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@@ -212,6 +212,7 @@ class LibCallSimplifier {
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Value *optimizeTrigInversionPairs(CallInst *CI, IRBuilderBase &B);
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Value *optimizeSymmetric(CallInst *CI, LibFunc Func, IRBuilderBase &B);
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Value *optimizeRemquo(CallInst *CI, IRBuilderBase &B);
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Value *optimizeFdim(CallInst *CI, IRBuilderBase &B);
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// Wrapper for all floating point library call optimizations
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Value *optimizeFloatingPointLibCall(CallInst *CI, LibFunc Func,
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IRBuilderBase &B);

‎llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

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@@ -3109,6 +3109,33 @@ Value *LibCallSimplifier::optimizeRemquo(CallInst *CI, IRBuilderBase &B) {
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return ConstantFP::get(CI->getType(), Rem);
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}
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/// Constant folds fdim
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Value *LibCallSimplifier::optimizeFdim(CallInst *CI, IRBuilderBase &B) {
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// Cannot perform the fold unless the call has attribute memory(none)
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if (!CI->doesNotAccessMemory())
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return nullptr;
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// TODO : Handle undef values
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// Propagate poison if any
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if (isa<PoisonValue>(CI->getArgOperand(0)))
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return CI->getArgOperand(0);
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if (isa<PoisonValue>(CI->getArgOperand(1)))
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return CI->getArgOperand(1);
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const APFloat *X, *Y;
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// Check if both values are constants
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if (!match(CI->getArgOperand(0), m_APFloat(X)) ||
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!match(CI->getArgOperand(1), m_APFloat(Y)))
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return nullptr;
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APFloat Difference = *X;
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Difference.subtract(*Y, RoundingMode::NearestTiesToEven);
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APFloat MaxVal =
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maximum(Difference, APFloat::getZero(CI->getType()->getFltSemantics()));
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return ConstantFP::get(CI->getType(), MaxVal);
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}
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//===----------------------------------------------------------------------===//
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// Integer Library Call Optimizations
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//===----------------------------------------------------------------------===//
@@ -4042,6 +4069,10 @@ Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
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if (hasFloatVersion(M, CI->getCalledFunction()->getName()))
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return optimizeBinaryDoubleFP(CI, Builder, TLI);
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return nullptr;
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case LibFunc_fdim:
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case LibFunc_fdimf:
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case LibFunc_fdiml:
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return optimizeFdim(CI, Builder);
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case LibFunc_fminf:
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case LibFunc_fmin:
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case LibFunc_fminl:

‎llvm/test/Transforms/InstCombine/fdim.ll

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@@ -0,0 +1,123 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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define double @fdim_double() {
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; CHECK-LABEL: define double @fdim_double() {
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; CHECK-NEXT: ret double 2.500000e+00
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;
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%dim = call double @fdim(double 10.5, double 8.0)
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ret double %dim
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}
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define double @fdim_double1() {
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; CHECK-LABEL: define double @fdim_double1() {
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; CHECK-NEXT: ret double 0.000000e+00
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;
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%dim = call double @fdim(double 7.0, double 8.0)
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ret double %dim
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}
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define float @fdim_float() {
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; CHECK-LABEL: define float @fdim_float() {
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; CHECK-NEXT: ret float 0.000000e+00
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;
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%dim = call float @fdimf(float 1.500000e+00, float 8.0)
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ret float %dim
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}
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define float @fdim_float1() {
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; CHECK-LABEL: define float @fdim_float1() {
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; CHECK-NEXT: ret float 2.000000e+00
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;
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%dim = call float @fdimf(float 1.000000e+01, float 8.0)
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ret float %dim
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}
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define double @fdim_poison1() {
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; CHECK-LABEL: define double @fdim_poison1() {
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; CHECK-NEXT: ret double poison
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;
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%dim = call double @fdim(double poison, double 1.0)
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ret double %dim
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}
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define double @fdim_poison2() {
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; CHECK-LABEL: define double @fdim_poison2() {
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; CHECK-NEXT: ret double poison
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;
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%dim = call double @fdim(double 1.0, double poison)
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ret double %dim
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}
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define double @fdim_poison3() {
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; CHECK-LABEL: define double @fdim_poison3() {
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; CHECK-NEXT: ret double poison
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;
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%dim = call double @fdim(double poison, double poison)
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ret double %dim
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}
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; undef folding is not implemented yet
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define double @fdim_undef1() {
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; CHECK-LABEL: define double @fdim_undef1() {
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; CHECK-NEXT: [[DIM:%.*]] = call double @fdim(double undef, double 1.000000e+00)
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; CHECK-NEXT: ret double [[DIM]]
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;
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%dim = call double @fdim(double undef, double 1.0)
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ret double %dim
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}
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define double @fdim_inf_ninf() {
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; CHECK-LABEL: define double @fdim_inf_ninf() {
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; CHECK-NEXT: ret double 0x7FF0000000000000
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;
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%dim = call double @fdim(double 0x7FF0000000000000, double 0x8000000000000000 )
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ret double %dim
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}
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define double @fdim_inf() {
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; CHECK-LABEL: define double @fdim_inf() {
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; CHECK-NEXT: ret double 0x7FF8000000000000
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;
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%dim = call double @fdim(double 0x7FF0000000000000, double 0x7FF0000000000000)
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ret double %dim
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}
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define double @fdim_nzero() {
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; CHECK-LABEL: define double @fdim_nzero() {
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; CHECK-NEXT: ret double 0.000000e+00
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;
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%dim = call double @fdim(double -0.0, double +0.0)
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ret double %dim
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}
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define double @fdim_strictfp() {
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; CHECK-LABEL: define double @fdim_strictfp() {
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; CHECK-NEXT: [[DIM:%.*]] = call double @fdim(double 1.000000e+01, double 8.000000e+00) #[[ATTR1:[0-9]+]]
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; CHECK-NEXT: ret double [[DIM]]
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;
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%dim = call double @fdim(double 10.0, double 8.0) strictfp
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ret double %dim
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}
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define double @fdim_nan1() {
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; CHECK-LABEL: define double @fdim_nan1() {
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; CHECK-NEXT: ret double 0x7FF8000000000000
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;
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%dim = call double @fdim(double 10.0, double 0x7FF8000000000000)
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ret double %dim
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}
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define double @fdim_nan2() {
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; CHECK-LABEL: define double @fdim_nan2() {
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; CHECK-NEXT: ret double 0x7FF8000000000000
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;
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%dim = call double @fdim(double 0x7FF8000000000000, double 1.4)
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ret double %dim
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}
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declare double @fdim(double, double) #0
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declare float @fdimf(float, float) #0
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attributes #0 = { memory(none) }

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