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[KnownBits] Pull out repeated getMinValue() calls from shift analysis. NFCI.

This commit is contained in:
Simon Pilgrim 2021-02-22 18:40:43 +00:00
parent 1c932baeaa
commit bb20cf2f1c
1 changed files with 10 additions and 7 deletions
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17
llvm/lib/Support/KnownBits.cpp
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@ -181,8 +181,9 @@ KnownBits KnownBits::shl(const KnownBits &LHS, const KnownBits &RHS) {
unsigned MinTrailingZeros = LHS.countMinTrailingZeros();
// Minimum shift amount low bits are known zero.
if (RHS.getMinValue().ult(BitWidth)) {
MinTrailingZeros += RHS.getMinValue().getZExtValue();
APInt MinShiftAmount = RHS.getMinValue();
if (MinShiftAmount.ult(BitWidth)) {
MinTrailingZeros += MinShiftAmount.getZExtValue();
MinTrailingZeros = std::min(MinTrailingZeros, BitWidth);
}
@ -208,8 +209,9 @@ KnownBits KnownBits::lshr(const KnownBits &LHS, const KnownBits &RHS) {
unsigned MinLeadingZeros = LHS.countMinLeadingZeros();
// Minimum shift amount high bits are known zero.
if (RHS.getMinValue().ult(BitWidth)) {
MinLeadingZeros += RHS.getMinValue().getZExtValue();
APInt MinShiftAmount = RHS.getMinValue();
if (MinShiftAmount.ult(BitWidth)) {
MinLeadingZeros += MinShiftAmount.getZExtValue();
MinLeadingZeros = std::min(MinLeadingZeros, BitWidth);
}
@ -234,13 +236,14 @@ KnownBits KnownBits::ashr(const KnownBits &LHS, const KnownBits &RHS) {
unsigned MinLeadingOnes = LHS.countMinLeadingOnes();
// Minimum shift amount high bits are known sign bits.
if (RHS.getMinValue().ult(BitWidth)) {
APInt MinShiftAmount = RHS.getMinValue();
if (MinShiftAmount.ult(BitWidth)) {
if (MinLeadingZeros) {
MinLeadingZeros += RHS.getMinValue().getZExtValue();
MinLeadingZeros += MinShiftAmount.getZExtValue();
MinLeadingZeros = std::min(MinLeadingZeros, BitWidth);
}
if (MinLeadingOnes) {
MinLeadingOnes += RHS.getMinValue().getZExtValue();
MinLeadingOnes += MinShiftAmount.getZExtValue();
MinLeadingOnes = std::min(MinLeadingOnes, BitWidth);
}
}