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| author | Simon Pilgrim <llvm-dev@redking.me.uk> | 2020-03-20 11:04:38 +0000 |
|---|---|---|
| committer | Simon Pilgrim <llvm-dev@redking.me.uk> | 2020-03-20 11:08:08 +0000 |
| commit | c1efdbcbe0dfef846a9774eea280a74b9ea19437 (patch) | |
| tree | c9bdbbb9cdde6a6a2c9595a11767e84b61e01cc5 /llvm/lib/Analysis/ValueTracking.cpp | |
| parent | a09ff56b5b5edc3aef0e2f572f9ffd1c4deb8e08 (diff) | |
| download | llvm-c1efdbcbe0dfef846a9774eea280a74b9ea19437.zip llvm-c1efdbcbe0dfef846a9774eea280a74b9ea19437.tar.gz llvm-c1efdbcbe0dfef846a9774eea280a74b9ea19437.tar.bz2 | |
[ValueTracking] Add computeKnownBits DemandedElts support to shift instructions (PR36319)
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 7a7be5bd..ea6391d 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -1003,16 +1003,17 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, /// amount. The results from calling KZF and KOF are conservatively combined for /// all permitted shift amounts. static void computeKnownBitsFromShiftOperator( - const Operator *I, KnownBits &Known, KnownBits &Known2, - unsigned Depth, const Query &Q, + const Operator *I, const APInt &DemandedElts, KnownBits &Known, + KnownBits &Known2, unsigned Depth, const Query &Q, function_ref<APInt(const APInt &, unsigned)> KZF, function_ref<APInt(const APInt &, unsigned)> KOF) { unsigned BitWidth = Known.getBitWidth(); - if (auto *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { - unsigned ShiftAmt = SA->getLimitedValue(BitWidth-1); + computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); + if (Known.isConstant()) { + unsigned ShiftAmt = Known.getConstant().getLimitedValue(BitWidth - 1); - computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); + computeKnownBits(I->getOperand(0), DemandedElts, Known, Depth + 1, Q); Known.Zero = KZF(Known.Zero, ShiftAmt); Known.One = KOF(Known.One, ShiftAmt); // If the known bits conflict, this must be an overflowing left shift, so @@ -1024,11 +1025,10 @@ static void computeKnownBitsFromShiftOperator( return; } - computeKnownBits(I->getOperand(1), Known, Depth + 1, Q); - // If the shift amount could be greater than or equal to the bit-width of the // LHS, the value could be poison, but bail out because the check below is - // expensive. TODO: Should we just carry on? + // expensive. + // TODO: Should we just carry on? if (Known.getMaxValue().uge(BitWidth)) { Known.resetAll(); return; @@ -1057,7 +1057,7 @@ static void computeKnownBitsFromShiftOperator( return; } - computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); + computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); Known.Zero.setAllBits(); Known.One.setAllBits(); @@ -1302,7 +1302,8 @@ static void computeKnownBitsFromOperator(const Operator *I, return KOResult; }; - computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); + computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, + KZF, KOF); break; } case Instruction::LShr: { @@ -1318,7 +1319,8 @@ static void computeKnownBitsFromOperator(const Operator *I, return KnownOne.lshr(ShiftAmt); }; - computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); + computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, + KZF, KOF); break; } case Instruction::AShr: { @@ -1331,7 +1333,8 @@ static void computeKnownBitsFromOperator(const Operator *I, return KnownOne.ashr(ShiftAmt); }; - computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); + computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, + KZF, KOF); break; } case Instruction::Sub: { |