diff options
Diffstat (limited to 'llvm/lib/Support/KnownBits.cpp')
| -rw-r--r-- | llvm/lib/Support/KnownBits.cpp | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/llvm/lib/Support/KnownBits.cpp b/llvm/lib/Support/KnownBits.cpp index 8bc6562..ce2813e 100644 --- a/llvm/lib/Support/KnownBits.cpp +++ b/llvm/lib/Support/KnownBits.cpp @@ -758,6 +758,13 @@ KnownBits KnownBits::sdiv(const KnownBits &LHS, const KnownBits &RHS, assert(!LHS.hasConflict() && !RHS.hasConflict() && "Bad inputs"); KnownBits Known(BitWidth); + if (LHS.isZero() || RHS.isZero()) { + // Result is either known Zero or UB. Return Zero either way. + // Checking this earlier saves us a lot of special cases later on. + Known.setAllZero(); + return Known; + } + std::optional<APInt> Res; if (LHS.isNegative() && RHS.isNegative()) { // Result non-negative. @@ -819,6 +826,13 @@ KnownBits KnownBits::udiv(const KnownBits &LHS, const KnownBits &RHS, assert(!LHS.hasConflict() && !RHS.hasConflict()); KnownBits Known(BitWidth); + if (LHS.isZero() || RHS.isZero()) { + // Result is either known Zero or UB. Return Zero either way. + // Checking this earlier saves us a lot of special cases later on. + Known.setAllZero(); + return Known; + } + // We can figure out the minimum number of upper zero bits by doing // MaxNumerator / MinDenominator. If the Numerator gets smaller or Denominator // gets larger, the number of upper zero bits increases. |