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| author | Jonathan Roelofs <jonathan@codesourcery.com> | 2016-08-10 19:50:14 +0000 |
|---|---|---|
| committer | Jonathan Roelofs <jonathan@codesourcery.com> | 2016-08-10 19:50:14 +0000 |
| commit | 851b79dc4d96c6331093d273fdc51eb3c65cb72b (patch) | |
| tree | 052d07c3ecce65c22c82242632b0412deaf5e343 /llvm/lib/Support/APInt.cpp | |
| parent | 9ef6b6b4f4e4004f260563e312036d7be132cfbf (diff) | |
| download | llvm-851b79dc4d96c6331093d273fdc51eb3c65cb72b.zip llvm-851b79dc4d96c6331093d273fdc51eb3c65cb72b.tar.gz llvm-851b79dc4d96c6331093d273fdc51eb3c65cb72b.tar.bz2 | |
Fix UB in APInt::ashr
i64 -1, whose sign bit is the 0th one, can't be left shifted without invoking UB.
https://reviews.llvm.org/D23362
llvm-svn: 278280
Diffstat (limited to 'llvm/lib/Support/APInt.cpp')
| -rw-r--r-- | llvm/lib/Support/APInt.cpp | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp index 8c921ce..31ffffc 100644 --- a/llvm/lib/Support/APInt.cpp +++ b/llvm/lib/Support/APInt.cpp @@ -1042,11 +1042,7 @@ APInt APInt::ashr(unsigned shiftAmt) const { if (isSingleWord()) { if (shiftAmt == BitWidth) return APInt(BitWidth, 0); // undefined - else { - unsigned SignBit = APINT_BITS_PER_WORD - BitWidth; - return APInt(BitWidth, - (((int64_t(VAL) << SignBit) >> SignBit) >> shiftAmt)); - } + return APInt(BitWidth, SignExtend64(VAL, BitWidth) >> shiftAmt); } // If all the bits were shifted out, the result is, technically, undefined. |