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ValueTracking: Start enhancing isKnownNeverNaN 

llvm-svn: 339399
This commit is contained in:
Matt Arsenault 2018-08-09 22:40:08 +00:00
parent 41b25c6cf4
commit d54b7f0592
5 changed files with 97 additions and 15 deletions
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3
llvm/include/llvm/Analysis/ValueTracking.h
View File

@ -194,7 +194,8 @@ class Value;
/// Return true if the floating-point scalar value is not a NaN or if the
/// floating-point vector value has no NaN elements. Return false if a value
/// could ever be NaN.
bool isKnownNeverNaN(const Value *V);
bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
unsigned Depth = 0);
/// Return true if we can prove that the specified FP value's sign bit is 0.
///

20
llvm/lib/Analysis/InstructionSimplify.cpp
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@ -1694,7 +1694,8 @@ static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
return nullptr;
}
static Value *simplifyAndOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
static Value *simplifyAndOrOfFCmps(const TargetLibraryInfo *TLI,
FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
if (LHS0->getType() != RHS0->getType())
@ -1711,8 +1712,8 @@ static Value *simplifyAndOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
// (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X
// (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y
// (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X
if ((isKnownNeverNaN(LHS0) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
(isKnownNeverNaN(LHS1) && (LHS0 == RHS0 || LHS0 == RHS1)))
if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
(isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1)))
return RHS;
// (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y
@ -1723,15 +1724,16 @@ static Value *simplifyAndOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
// (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X
// (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y
// (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X
if ((isKnownNeverNaN(RHS0) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
(isKnownNeverNaN(RHS1) && (RHS0 == LHS0 || RHS0 == LHS1)))
if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
(isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1)))
return LHS;
}
return nullptr;
}
static Value *simplifyAndOrOfCmps(Value *Op0, Value *Op1, bool IsAnd) {
static Value *simplifyAndOrOfCmps(const TargetLibraryInfo *TLI,
Value *Op0, Value *Op1, bool IsAnd) {
// Look through casts of the 'and' operands to find compares.
auto *Cast0 = dyn_cast<CastInst>(Op0);
auto *Cast1 = dyn_cast<CastInst>(Op1);
@ -1751,7 +1753,7 @@ static Value *simplifyAndOrOfCmps(Value *Op0, Value *Op1, bool IsAnd) {
auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
if (FCmp0 && FCmp1)
V = simplifyAndOrOfFCmps(FCmp0, FCmp1, IsAnd);
V = simplifyAndOrOfFCmps(TLI, FCmp0, FCmp1, IsAnd);
if (!V)
return nullptr;
@ -1831,7 +1833,7 @@ static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
return Op1;
}
if (Value *V = simplifyAndOrOfCmps(Op0, Op1, true))
if (Value *V = simplifyAndOrOfCmps(Q.TLI, Op0, Op1, true))
return V;
// Try some generic simplifications for associative operations.
@ -1981,7 +1983,7 @@ static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
return Op0;
if (Value *V = simplifyAndOrOfCmps(Op0, Op1, false))
if (Value *V = simplifyAndOrOfCmps(Q.TLI, Op0, Op1, false))
return V;
// Try some generic simplifications for associative operations.

24
llvm/lib/Analysis/ValueTracking.cpp
View File

@ -2841,10 +2841,10 @@ static bool cannotBeOrderedLessThanZeroImpl(const Value *V,
default:
break;
case Intrinsic::maxnum:
return (isKnownNeverNaN(I->getOperand(0)) &&
return (isKnownNeverNaN(I->getOperand(0), TLI) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI,
SignBitOnly, Depth + 1)) ||
(isKnownNeverNaN(I->getOperand(1)) &&
(isKnownNeverNaN(I->getOperand(1), TLI) &&
cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI,
SignBitOnly, Depth + 1));
@ -2909,7 +2909,8 @@ bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0);
}
bool llvm::isKnownNeverNaN(const Value *V) {
bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
unsigned Depth) {
assert(V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type");
// If we're told that NaNs won't happen, assume they won't.
@ -2924,6 +2925,23 @@ bool llvm::isKnownNeverNaN(const Value *V) {
if (auto *CFP = dyn_cast<ConstantFP>(V))
return !CFP->isNaN();
if (Depth == MaxDepth)
return false;
if (const auto *II = dyn_cast<IntrinsicInst>(V)) {
switch (II->getIntrinsicID()) {
case Intrinsic::canonicalize:
case Intrinsic::fabs:
case Intrinsic::copysign:
return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1);
case Intrinsic::sqrt:
return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) &&
CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI);
default:
return false;
}
}
// Bail out for constant expressions, but try to handle vector constants.
if (!V->getType()->isVectorTy() || !isa<Constant>(V))
return false;

4
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -5153,11 +5153,11 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
// If we're just checking for a NaN (ORD/UNO) and have a non-NaN operand,
// then canonicalize the operand to 0.0.
if (Pred == CmpInst::FCMP_ORD || Pred == CmpInst::FCMP_UNO) {
if (!match(Op0, m_PosZeroFP()) && isKnownNeverNaN(Op0)) {
if (!match(Op0, m_PosZeroFP()) && isKnownNeverNaN(Op0, &TLI)) {
I.setOperand(0, ConstantFP::getNullValue(Op0->getType()));
return &I;
}
if (!match(Op1, m_PosZeroFP()) && isKnownNeverNaN(Op1)) {
if (!match(Op1, m_PosZeroFP()) && isKnownNeverNaN(Op1, &TLI)) {
I.setOperand(1, ConstantFP::getNullValue(Op0->getType()));
return &I;
}

61
llvm/test/Transforms/InstCombine/known-never-nan.ll Normal file
View File

@ -0,0 +1,61 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine %s | FileCheck %s
define i1 @nnan_fabs_src(double %arg) {
; CHECK-LABEL: @nnan_fabs_src(
; CHECK-NEXT: ret i1 true
;
%nnan = fadd nnan double %arg, 1.0
%op = call double @llvm.fabs.f64(double %nnan)
%tmp = fcmp ord double %op, %op
ret i1 %tmp
}
define i1 @nnan_opicalize_src(double %arg) {
; CHECK-LABEL: @nnan_opicalize_src(
; CHECK-NEXT: ret i1 true
;
%nnan = fadd nnan double %arg, 1.0
%op = call double @llvm.canonicalize.f64(double %nnan)
%tmp = fcmp ord double %op, %op
ret i1 %tmp
}
define i1 @nnan_copysign_src(double %arg0, double %arg1) {
; CHECK-LABEL: @nnan_copysign_src(
; CHECK-NEXT: ret i1 true
;
%nnan = fadd nnan double %arg0, 1.0
%op = call double @llvm.copysign.f64(double %nnan, double %arg1)
%tmp = fcmp ord double %op, %op
ret i1 %tmp
}
define i1 @fabs_sqrt_src(double %arg0, double %arg1) {
; CHECK-LABEL: @fabs_sqrt_src(
; CHECK-NEXT: ret i1 true
;
%nnan = fadd nnan double %arg0, 1.0
%fabs = call double @llvm.fabs.f64(double %nnan)
%op = call double @llvm.sqrt.f64(double %fabs)
%tmp = fcmp ord double %op, %op
ret i1 %tmp
}
define i1 @fabs_sqrt_src_maybe_nan(double %arg0, double %arg1) {
; CHECK-LABEL: @fabs_sqrt_src_maybe_nan(
; CHECK-NEXT: [[FABS:%.*]] = call double @llvm.fabs.f64(double [[ARG0:%.*]])
; CHECK-NEXT: [[OP:%.*]] = call double @llvm.sqrt.f64(double [[FABS]])
; CHECK-NEXT: [[TMP:%.*]] = fcmp ord double [[OP]], 0.000000e+00
; CHECK-NEXT: ret i1 [[TMP]]
;
%fabs = call double @llvm.fabs.f64(double %arg0)
%op = call double @llvm.sqrt.f64(double %fabs)
%tmp = fcmp ord double %op, %op
ret i1 %tmp
}
declare double @llvm.sqrt.f64(double)
declare double @llvm.fabs.f64(double)
declare double @llvm.canonicalize.f64(double)
declare double @llvm.copysign.f64(double, double)