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InstSimplify: Eliminate fabs on known positive

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291624 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matt Arsenault 2017-01-11 00:33:24 +00:00
parent a618f4d4ce
commit 1f4353fb62
6 changed files with 212 additions and 32 deletions
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8
include/llvm/Analysis/ValueTracking.h
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@ -169,8 +169,12 @@ template <typename T> class ArrayRef;
/// Return true if we can prove that the specified FP value is either a NaN or
/// never less than 0.0.
bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI,
unsigned Depth = 0);
/// If \p IncludeNeg0 is false, -0.0 is considered less than 0.0.
bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);
/// \returns true if we can prove that the specified FP value has a 0 sign
/// bit.
bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);
/// If the specified value can be set by repeating the same byte in memory,
/// return the i8 value that it is represented with. This is true for all i8

15
lib/Analysis/InstructionSimplify.cpp
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@ -4308,10 +4308,21 @@ static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
return nullptr;
// Unary Ops
if (NumOperands == 1)
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
if (NumOperands == 1) {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin)) {
if (II->getIntrinsicID() == IID)
return II;
}
switch (IID) {
case Intrinsic::fabs: {
if (SignBitMustBeZero(*ArgBegin, Q.TLI))
return *ArgBegin;
}
default:
break;
}
}
return nullptr;
}

71
lib/Analysis/ValueTracking.cpp
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@ -2580,51 +2580,70 @@ bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
return false;
}
bool llvm::CannotBeOrderedLessThanZero(const Value *V,
const TargetLibraryInfo *TLI,
unsigned Depth) {
if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V))
return !CFP->getValueAPF().isNegative() || CFP->getValueAPF().isZero();
/// If \p SignBitOnly is true, test for a known 0 sign bit rather than a
/// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign
/// bit despite comparing equal.
static bool cannotBeOrderedLessThanZeroImpl(const Value *V,
const TargetLibraryInfo *TLI,
bool SignBitOnly,
unsigned Depth) {
if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
return !CFP->getValueAPF().isNegative() ||
(!SignBitOnly && CFP->getValueAPF().isZero());
}
if (Depth == MaxDepth)
return false; // Limit search depth.
return false; // Limit search depth.
const Operator *I = dyn_cast<Operator>(V);
if (!I) return false;
if (!I)
return false;
switch (I->getOpcode()) {
default: break;
default:
break;
// Unsigned integers are always nonnegative.
case Instruction::UIToFP:
return true;
case Instruction::FMul:
// x*x is always non-negative or a NaN.
if (I->getOperand(0) == I->getOperand(1))
if (I->getOperand(0) == I->getOperand(1) &&
(!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()))
return true;
LLVM_FALLTHROUGH;
case Instruction::FAdd:
case Instruction::FDiv:
case Instruction::FRem:
return CannotBeOrderedLessThanZero(I->getOperand(0), TLI, Depth + 1) &&
CannotBeOrderedLessThanZero(I->getOperand(1), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
Depth + 1) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
Depth + 1);
case Instruction::Select:
return CannotBeOrderedLessThanZero(I->getOperand(1), TLI, Depth + 1) &&
CannotBeOrderedLessThanZero(I->getOperand(2), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
Depth + 1) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly,
Depth + 1);
case Instruction::FPExt:
case Instruction::FPTrunc:
// Widening/narrowing never change sign.
return CannotBeOrderedLessThanZero(I->getOperand(0), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
Depth + 1);
case Instruction::Call:
Intrinsic::ID IID = getIntrinsicForCallSite(cast<CallInst>(I), TLI);
switch (IID) {
default:
break;
case Intrinsic::maxnum:
return CannotBeOrderedLessThanZero(I->getOperand(0), TLI, Depth + 1) ||
CannotBeOrderedLessThanZero(I->getOperand(1), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
Depth + 1) ||
cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
Depth + 1);
case Intrinsic::minnum:
return CannotBeOrderedLessThanZero(I->getOperand(0), TLI, Depth + 1) &&
CannotBeOrderedLessThanZero(I->getOperand(1), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
Depth + 1) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
Depth + 1);
case Intrinsic::exp:
case Intrinsic::exp2:
case Intrinsic::fabs:
@ -2636,18 +2655,30 @@ bool llvm::CannotBeOrderedLessThanZero(const Value *V,
if (CI->getBitWidth() <= 64 && CI->getSExtValue() % 2u == 0)
return true;
}
return CannotBeOrderedLessThanZero(I->getOperand(0), TLI, Depth + 1);
return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
Depth + 1);
case Intrinsic::fma:
case Intrinsic::fmuladd:
// x*x+y is non-negative if y is non-negative.
return I->getOperand(0) == I->getOperand(1) &&
CannotBeOrderedLessThanZero(I->getOperand(2), TLI, Depth + 1);
(!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly,
Depth + 1);
}
break;
}
return false;
}
bool llvm::CannotBeOrderedLessThanZero(const Value *V,
const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0);
}
bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0);
}
/// If the specified value can be set by repeating the same byte in memory,
/// return the i8 value that it is represented with. This is
/// true for all i8 values obviously, but is also true for i32 0, i32 -1,

50
test/Transforms/InstCombine/fabs.ll
View File

@ -5,6 +5,8 @@
declare float @fabsf(float)
declare double @fabs(double)
declare fp128 @fabsl(fp128)
declare float @llvm.fma.f32(float, float, float)
declare float @llvm.fmuladd.f32(float, float, float)
define float @square_fabs_call_f32(float %x) {
%mul = fmul float %x, %x
@ -80,7 +82,6 @@ define fp128 @square_fabs_intrinsic_f128(fp128 %x) {
; CHECK-NEXT: ret fp128 %fabsl
}
; TODO: This should be able to elimnated the fabs
define float @square_nnan_fabs_intrinsic_f32(float %x) {
%mul = fmul nnan float %x, %x
%fabsf = call float @llvm.fabs.f32(float %mul)
@ -88,8 +89,7 @@ define float @square_nnan_fabs_intrinsic_f32(float %x) {
; CHECK-LABEL: square_nnan_fabs_intrinsic_f32(
; CHECK-NEXT: %mul = fmul nnan float %x, %x
; CHECK-NEXT: %fabsf = call float @llvm.fabs.f32(float %mul)
; CHECK-NEXT: ret float %fabsf
; CHECK-NEXT: ret float %mul
}
; Shrinking a library call to a smaller type should not be inhibited by nor inhibit the square optimization.
@ -170,3 +170,47 @@ define float @fabs_select_var_constant_negative(i32 %c, float %x) {
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; The fabs cannot be eliminated because %x may be a NaN
define float @square_fma_fabs_intrinsic_f32(float %x) {
%fma = call float @llvm.fma.f32(float %x, float %x, float 1.0)
%fabsf = call float @llvm.fabs.f32(float %fma)
ret float %fabsf
; CHECK-LABEL: @square_fma_fabs_intrinsic_f32(
; CHECK-NEXT: %fma = call float @llvm.fma.f32(float %x, float %x, float 1.000000e+00)
; CHECK-NEXT: %fabsf = call float @llvm.fabs.f32(float %fma)
; CHECK-NEXT: ret float %fabsf
}
; The fabs cannot be eliminated because %x may be a NaN
define float @square_nnan_fma_fabs_intrinsic_f32(float %x) {
%fma = call nnan float @llvm.fma.f32(float %x, float %x, float 1.0)
%fabsf = call float @llvm.fabs.f32(float %fma)
ret float %fabsf
; CHECK-LABEL: @square_nnan_fma_fabs_intrinsic_f32(
; CHECK-NEXT: %fma = call nnan float @llvm.fma.f32(float %x, float %x, float 1.000000e+00)
; CHECK-NEXT: ret float %fma
}
define float @square_fmuladd_fabs_intrinsic_f32(float %x) {
%fmuladd = call float @llvm.fmuladd.f32(float %x, float %x, float 1.0)
%fabsf = call float @llvm.fabs.f32(float %fmuladd)
ret float %fabsf
; CHECK-LABEL: @square_fmuladd_fabs_intrinsic_f32(
; CHECK-NEXT: %fmuladd = call float @llvm.fmuladd.f32(float %x, float %x, float 1.000000e+00)
; CHECK-NEXT: %fabsf = call float @llvm.fabs.f32(float %fmuladd)
; CHECK-NEXT: ret float %fabsf
}
define float @square_nnan_fmuladd_fabs_intrinsic_f32(float %x) {
%fmuladd = call nnan float @llvm.fmuladd.f32(float %x, float %x, float 1.0)
%fabsf = call float @llvm.fabs.f32(float %fmuladd)
ret float %fabsf
; CHECK-LABEL: @square_nnan_fmuladd_fabs_intrinsic_f32(
; CHECK-NEXT: %fmuladd = call nnan float @llvm.fmuladd.f32(float %x, float %x, float 1.000000e+00)
; CHECK-NEXT: ret float %fmuladd
}

8
test/Transforms/InstCombine/fast-math.ll
View File

@ -241,7 +241,7 @@ define float @fmul2(float %f1) {
; X/C1 * C2 => X * (C2/C1) is disabled if X/C1 has multiple uses
@fmul2_external = external global float
define float @fmul2_disable(float %f1) {
%div = fdiv fast float 1.000000e+00, %f1
%div = fdiv fast float 1.000000e+00, %f1
store float %div, float* @fmul2_external
%mul = fmul fast float %div, 2.000000e+00
ret float %mul
@ -672,8 +672,7 @@ define double @sqrt_intrinsic_arg_4th(double %x) {
; CHECK-LABEL: sqrt_intrinsic_arg_4th(
; CHECK-NEXT: %mul = fmul fast double %x, %x
; CHECK-NEXT: %fabs = call fast double @llvm.fabs.f64(double %mul)
; CHECK-NEXT: ret double %fabs
; CHECK-NEXT: ret double %mul
}
define double @sqrt_intrinsic_arg_5th(double %x) {
@ -685,9 +684,8 @@ define double @sqrt_intrinsic_arg_5th(double %x) {
; CHECK-LABEL: sqrt_intrinsic_arg_5th(
; CHECK-NEXT: %mul = fmul fast double %x, %x
; CHECK-NEXT: %fabs = call fast double @llvm.fabs.f64(double %mul)
; CHECK-NEXT: %sqrt1 = call fast double @llvm.sqrt.f64(double %x)
; CHECK-NEXT: %1 = fmul fast double %fabs, %sqrt1
; CHECK-NEXT: %1 = fmul fast double %mul, %sqrt1
; CHECK-NEXT: ret double %1
}

92
test/Transforms/InstSimplify/floating-point-arithmetic.ll
View File

@ -103,3 +103,95 @@ define float @PR22688(float %x) {
ret float %7
}
declare float @llvm.fabs.f32(float)
; CHECK-LABEL: @fabs_select_positive_constants(
; CHECK: %select = select i1 %cmp, float 1.000000e+00, float 2.000000e+00
; CHECK-NEXT: ret float %select
define float @fabs_select_positive_constants(i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 1.0, float 2.0
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_constant_variable(
; CHECK: %select = select i1 %cmp, float 1.000000e+00, float %x
; CHECK-NEXT: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_constant_variable(i32 %c, float %x) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 1.0, float %x
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_neg0_pos0(
; CHECK: %select = select i1 %cmp, float -0.000000e+00, float 0.000000e+00
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
; CHECK-NEXT: ret float %fabs
define float @fabs_select_neg0_pos0(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float -0.0, float 0.0
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_neg0_neg1(
; CHECK: %select = select i1 %cmp, float -0.000000e+00, float -1.000000e+00
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_neg0_neg1(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float -0.0, float -1.0
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_nan_nan(
; CHECK: %select = select i1 %cmp, float 0x7FF8000000000000, float 0x7FF8000100000000
; CHECK-NEXT: ret float %select
define float @fabs_select_nan_nan(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 0x7FF8000000000000, float 0x7FF8000100000000
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_negnan_nan(
; CHECK: %select = select i1 %cmp, float 0xFFF8000000000000, float 0x7FF8000000000000
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_negnan_nan(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 0xFFF8000000000000, float 0x7FF8000000000000
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_negnan_negnan(
; CHECK: %select = select i1 %cmp, float 0xFFF8000000000000, float 0x7FF8000100000000
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_negnan_negnan(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 0xFFF8000000000000, float 0x7FF8000100000000
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_negnan_negzero(
; CHECK: %select = select i1 %cmp, float 0xFFF8000000000000, float -0.000000e+00
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_negnan_negzero(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 0xFFF8000000000000, float -0.0
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
; CHECK-LABEL: @fabs_select_negnan_zero(
; CHECK: %select = select i1 %cmp, float 0xFFF8000000000000, float 0.000000e+00
; CHECK: %fabs = call float @llvm.fabs.f32(float %select)
define float @fabs_select_negnan_zero(float addrspace(1)* %out, i32 %c) {
%cmp = icmp eq i32 %c, 0
%select = select i1 %cmp, float 0xFFF8000000000000, float 0.0
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}