diff options
Diffstat (limited to 'llvm/lib/Support/KnownBits.cpp')
| -rw-r--r-- | llvm/lib/Support/KnownBits.cpp | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/llvm/lib/Support/KnownBits.cpp b/llvm/lib/Support/KnownBits.cpp index a7ca7c0..84e23d4 100644 --- a/llvm/lib/Support/KnownBits.cpp +++ b/llvm/lib/Support/KnownBits.cpp @@ -172,7 +172,7 @@ static unsigned getMaxShiftAmount(const APInt &MaxValue, unsigned BitWidth) { } KnownBits KnownBits::shl(const KnownBits &LHS, const KnownBits &RHS, bool NUW, - bool NSW) { + bool NSW, bool ShAmtNonZero) { unsigned BitWidth = LHS.getBitWidth(); auto ShiftByConst = [&](const KnownBits &LHS, unsigned ShiftAmt) { KnownBits Known; @@ -198,6 +198,8 @@ KnownBits KnownBits::shl(const KnownBits &LHS, const KnownBits &RHS, bool NUW, // Fast path for a common case when LHS is completely unknown. KnownBits Known(BitWidth); unsigned MinShiftAmount = RHS.getMinValue().getLimitedValue(BitWidth); + if (MinShiftAmount == 0 && ShAmtNonZero) + MinShiftAmount = 1; if (LHS.isUnknown()) { Known.Zero.setLowBits(MinShiftAmount); if (NUW && NSW && MinShiftAmount != 0) @@ -254,7 +256,8 @@ KnownBits KnownBits::shl(const KnownBits &LHS, const KnownBits &RHS, bool NUW, return Known; } -KnownBits KnownBits::lshr(const KnownBits &LHS, const KnownBits &RHS) { +KnownBits KnownBits::lshr(const KnownBits &LHS, const KnownBits &RHS, + bool ShAmtNonZero) { unsigned BitWidth = LHS.getBitWidth(); auto ShiftByConst = [&](const KnownBits &LHS, unsigned ShiftAmt) { KnownBits Known = LHS; @@ -268,6 +271,8 @@ KnownBits KnownBits::lshr(const KnownBits &LHS, const KnownBits &RHS) { // Fast path for a common case when LHS is completely unknown. KnownBits Known(BitWidth); unsigned MinShiftAmount = RHS.getMinValue().getLimitedValue(BitWidth); + if (MinShiftAmount == 0 && ShAmtNonZero) + MinShiftAmount = 1; if (LHS.isUnknown()) { Known.Zero.setHighBits(MinShiftAmount); return Known; @@ -297,7 +302,8 @@ KnownBits KnownBits::lshr(const KnownBits &LHS, const KnownBits &RHS) { return Known; } -KnownBits KnownBits::ashr(const KnownBits &LHS, const KnownBits &RHS) { +KnownBits KnownBits::ashr(const KnownBits &LHS, const KnownBits &RHS, + bool ShAmtNonZero) { unsigned BitWidth = LHS.getBitWidth(); auto ShiftByConst = [&](const KnownBits &LHS, unsigned ShiftAmt) { KnownBits Known = LHS; @@ -309,6 +315,8 @@ KnownBits KnownBits::ashr(const KnownBits &LHS, const KnownBits &RHS) { // Fast path for a common case when LHS is completely unknown. KnownBits Known(BitWidth); unsigned MinShiftAmount = RHS.getMinValue().getLimitedValue(BitWidth); + if (MinShiftAmount == 0 && ShAmtNonZero) + MinShiftAmount = 1; if (LHS.isUnknown()) { if (MinShiftAmount == BitWidth) { // Always poison. Return zero because we don't like returning conflict. |