[llvm] r355099 - Add support for computing "zext of value" in KnownBits. NFCI
Bjorn Pettersson via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 28 07:45:29 PST 2019
Author: bjope
Date: Thu Feb 28 07:45:29 2019
New Revision: 355099
URL: http://llvm.org/viewvc/llvm-project?rev=355099&view=rev
Log:
Add support for computing "zext of value" in KnownBits. NFCI
Summary:
The description of KnownBits::zext() and
KnownBits::zextOrTrunc() has confusingly been telling
that the operation is equivalent to zero extending the
value we're tracking. That has not been true, instead
the user has been forced to explicitly set the extended
bits as known zero afterwards.
This patch adds a second argument to KnownBits::zext()
and KnownBits::zextOrTrunc() to control if the extended
bits should be considered as known zero or as unknown.
Reviewers: craig.topper, RKSimon
Reviewed By: RKSimon
Subscribers: javed.absar, hiraditya, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58650
Modified:
llvm/trunk/include/llvm/Support/KnownBits.h
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
Modified: llvm/trunk/include/llvm/Support/KnownBits.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/KnownBits.h?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/KnownBits.h (original)
+++ llvm/trunk/include/llvm/Support/KnownBits.h Thu Feb 28 07:45:29 2019
@@ -113,10 +113,16 @@ public:
return KnownBits(Zero.trunc(BitWidth), One.trunc(BitWidth));
}
- /// Zero extends the underlying known Zero and One bits. This is equivalent
- /// to zero extending the value we're tracking.
- KnownBits zext(unsigned BitWidth) {
- return KnownBits(Zero.zext(BitWidth), One.zext(BitWidth));
+ /// Extends the underlying known Zero and One bits.
+ /// By setting ExtendedBitsAreKnownZero=true this will be equivalent to
+ /// zero extending the value we're tracking.
+ /// With ExtendedBitsAreKnownZero=false the extended bits are set to unknown.
+ KnownBits zext(unsigned BitWidth, bool ExtendedBitsAreKnownZero) {
+ unsigned OldBitWidth = getBitWidth();
+ APInt NewZero = Zero.zext(BitWidth);
+ if (ExtendedBitsAreKnownZero)
+ NewZero.setBitsFrom(OldBitWidth);
+ return KnownBits(NewZero, One.zext(BitWidth));
}
/// Sign extends the underlying known Zero and One bits. This is equivalent
@@ -125,9 +131,13 @@ public:
return KnownBits(Zero.sext(BitWidth), One.sext(BitWidth));
}
- /// Zero extends or truncates the underlying known Zero and One bits. This is
- /// equivalent to zero extending or truncating the value we're tracking.
- KnownBits zextOrTrunc(unsigned BitWidth) {
+ /// Extends or truncates the underlying known Zero and One bits. When
+ /// extending the extended bits can either be set as known zero (if
+ /// ExtendedBitsAreKnownZero=true) or as unknown (if
+ /// ExtendedBitsAreKnownZero=false).
+ KnownBits zextOrTrunc(unsigned BitWidth, bool ExtendedBitsAreKnownZero) {
+ if (BitWidth > getBitWidth())
+ return zext(BitWidth, ExtendedBitsAreKnownZero);
return KnownBits(Zero.zextOrTrunc(BitWidth), One.zextOrTrunc(BitWidth));
}
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Thu Feb 28 07:45:29 2019
@@ -1128,12 +1128,9 @@ static void computeKnownBitsFromOperator
Q.DL.getTypeSizeInBits(ScalarTy);
assert(SrcBitWidth && "SrcBitWidth can't be zero");
- Known = Known.zextOrTrunc(SrcBitWidth);
+ Known = Known.zextOrTrunc(SrcBitWidth, false);
computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
- Known = Known.zextOrTrunc(BitWidth);
- // Any top bits are known to be zero.
- if (BitWidth > SrcBitWidth)
- Known.Zero.setBitsFrom(SrcBitWidth);
+ Known = Known.zextOrTrunc(BitWidth, true /* ExtendedBitsAreKnownZero */);
break;
}
case Instruction::BitCast: {
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp Thu Feb 28 07:45:29 2019
@@ -400,7 +400,7 @@ FunctionLoweringInfo::GetLiveOutRegInfo(
if (BitWidth > LOI->Known.getBitWidth()) {
LOI->NumSignBits = 1;
- LOI->Known = LOI->Known.zextOrTrunc(BitWidth);
+ LOI->Known = LOI->Known.zext(BitWidth, false /* => any extend */);
}
return LOI;
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Thu Feb 28 07:45:29 2019
@@ -2800,15 +2800,12 @@ KnownBits SelectionDAG::computeKnownBits
EVT InVT = Op.getOperand(0).getValueType();
APInt InDemandedElts = DemandedElts.zextOrSelf(InVT.getVectorNumElements());
Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
- Known = Known.zext(BitWidth);
- Known.Zero.setBitsFrom(InVT.getScalarSizeInBits());
+ Known = Known.zext(BitWidth, true /* ExtendedBitsAreKnownZero */);
break;
}
case ISD::ZERO_EXTEND: {
- EVT InVT = Op.getOperand(0).getValueType();
Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
- Known = Known.zext(BitWidth);
- Known.Zero.setBitsFrom(InVT.getScalarSizeInBits());
+ Known = Known.zext(BitWidth, true /* ExtendedBitsAreKnownZero */);
break;
}
case ISD::SIGN_EXTEND_VECTOR_INREG: {
@@ -2829,7 +2826,7 @@ KnownBits SelectionDAG::computeKnownBits
}
case ISD::ANY_EXTEND: {
Known = computeKnownBits(Op.getOperand(0), Depth+1);
- Known = Known.zext(BitWidth);
+ Known = Known.zext(BitWidth, false /* ExtendedBitsAreKnownZero */);
break;
}
case ISD::TRUNCATE: {
@@ -3026,7 +3023,7 @@ KnownBits SelectionDAG::computeKnownBits
Known = computeKnownBits(InVec, Depth + 1);
}
if (BitWidth > EltBitWidth)
- Known = Known.zext(BitWidth);
+ Known = Known.zext(BitWidth, false /* => any extend */);
break;
}
case ISD::INSERT_VECTOR_ELT: {
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Thu Feb 28 07:45:29 2019
@@ -1163,8 +1163,8 @@ bool TargetLowering::SimplifyDemandedBit
if (SimplifyDemandedBits(Src, InDemandedBits, Known, TLO, Depth + 1))
return true;
assert(!Known.hasConflict() && "Bits known to be one AND zero?");
- Known = Known.zext(BitWidth);
- Known.Zero.setBitsFrom(InBits);
+ assert(Known.getBitWidth() == InBits && "Src width has changed?");
+ Known = Known.zext(BitWidth, true /* ExtendedBitsAreKnownZero */);
break;
}
case ISD::SIGN_EXTEND: {
@@ -1217,7 +1217,7 @@ bool TargetLowering::SimplifyDemandedBit
if (SimplifyDemandedBits(Src, InDemandedBits, Known, TLO, Depth + 1))
return true;
assert(!Known.hasConflict() && "Bits known to be one AND zero?");
- Known = Known.zext(BitWidth);
+ Known = Known.zext(BitWidth, false /* => any extend */);
break;
}
case ISD::TRUNCATE: {
@@ -1312,7 +1312,7 @@ bool TargetLowering::SimplifyDemandedBit
Known = Known2;
if (BitWidth > EltBitWidth)
- Known = Known.zext(BitWidth);
+ Known = Known.zext(BitWidth, false /* => any extend */);
break;
}
case ISD::BITCAST: {
Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Thu Feb 28 07:45:29 2019
@@ -13706,8 +13706,7 @@ void ARMTargetLowering::computeKnownBits
if (Op.getOpcode() == ARMISD::VGETLANEs)
Known = Known.sext(DstSz);
else {
- Known = Known.zext(DstSz);
- Known.Zero.setBitsFrom(SrcSz);
+ Known = Known.zext(DstSz, true /* extended bits are known zero */);
}
assert(DstSz == Known.getBitWidth());
break;
Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Thu Feb 28 07:45:29 2019
@@ -6053,12 +6053,10 @@ SystemZTargetLowering::computeKnownBitsF
case Intrinsic::s390_vuplhw:
case Intrinsic::s390_vuplf: {
SDValue SrcOp = Op.getOperand(1);
- unsigned SrcBitWidth = SrcOp.getScalarValueSizeInBits();
APInt SrcDemE = getDemandedSrcElements(Op, DemandedElts, 0);
Known = DAG.computeKnownBits(SrcOp, SrcDemE, Depth + 1);
if (IsLogical) {
- Known = Known.zext(BitWidth);
- Known.Zero.setBitsFrom(SrcBitWidth);
+ Known = Known.zext(BitWidth, true);
} else
Known = Known.sext(BitWidth);
break;
@@ -6087,7 +6085,7 @@ SystemZTargetLowering::computeKnownBitsF
// Known has the width of the source operand(s). Adjust if needed to match
// the passed bitwidth.
if (Known.getBitWidth() != BitWidth)
- Known = Known.zextOrTrunc(BitWidth);
+ Known = Known.zextOrTrunc(BitWidth, false);
}
static unsigned computeNumSignBitsBinOp(SDValue Op, const APInt &DemandedElts,
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Feb 28 07:45:29 2019
@@ -30412,7 +30412,7 @@ void X86TargetLowering::computeKnownBits
APInt DemandedElt = APInt::getOneBitSet(SrcVT.getVectorNumElements(),
Op.getConstantOperandVal(1));
Known = DAG.computeKnownBits(Src, DemandedElt, Depth + 1);
- Known = Known.zextOrTrunc(BitWidth);
+ Known = Known.zextOrTrunc(BitWidth, false);
Known.Zero.setBitsFrom(SrcVT.getScalarSizeInBits());
break;
}
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp?rev=355099&r1=355098&r2=355099&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp Thu Feb 28 07:45:29 2019
@@ -365,10 +365,9 @@ Value *InstCombiner::SimplifyDemandedUse
KnownBits InputKnown(SrcBitWidth);
if (SimplifyDemandedBits(I, 0, InputDemandedMask, InputKnown, Depth + 1))
return I;
- Known = InputKnown.zextOrTrunc(BitWidth);
- // Any top bits are known to be zero.
- if (BitWidth > SrcBitWidth)
- Known.Zero.setBitsFrom(SrcBitWidth);
+ assert(InputKnown.getBitWidth() == SrcBitWidth && "Src width changed?");
+ Known = InputKnown.zextOrTrunc(BitWidth,
+ true /* ExtendedBitsAreKnownZero */);
assert(!Known.hasConflict() && "Bits known to be one AND zero?");
break;
}
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