[ConstantRange] Rewrite shl to avoid repeated calls to getUnsignedMax and avoid creating the min APInt until we're sure we need it. Use inplace shift operations.
llvm-svn: 302510
diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index 6801ed4..a33d062 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -892,16 +892,20 @@
if (isEmptySet() || Other.isEmptySet())
return ConstantRange(getBitWidth(), /*isFullSet=*/false);
- APInt min = getUnsignedMin().shl(Other.getUnsignedMin());
- APInt max = getUnsignedMax().shl(Other.getUnsignedMax());
+ APInt max = getUnsignedMax();
+ APInt Other_umax = Other.getUnsignedMax();
- // there's no overflow!
- APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
- if (Zeros.ugt(Other.getUnsignedMax()))
- return ConstantRange(std::move(min), std::move(max) + 1);
+ // there's overflow!
+ if (Other_umax.uge(max.countLeadingZeros()))
+ return ConstantRange(getBitWidth(), /*isFullSet=*/true);
// FIXME: implement the other tricky cases
- return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+
+ APInt min = getUnsignedMin();
+ min <<= Other.getUnsignedMin();
+ max <<= Other_umax;
+
+ return ConstantRange(std::move(min), std::move(max) + 1);
}
ConstantRange