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Fix shl to produce the correct result when the bitwidth is > 64 and the

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shift amount is 0. Previously this code would do a lshr by the bit width
which can lead to incorrect results.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37010 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer 2007-05-12 18:01:57 +00:00
parent 45d6764ca1
commit 92c7283500
1 changed files with 6 additions and 0 deletions
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6
lib/Support/APInt.cpp
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@ -1199,6 +1199,12 @@ APInt APInt::shl(uint32_t shiftAmt) const {
if (shiftAmt == BitWidth)
return APInt(BitWidth, 0);
// If none of the bits are shifted out, the result is *this. This avoids a
// lshr by the words size in the loop below which can produce incorrect
// results. It also avoids the expensive computation below for a common case.
if (shiftAmt == 0)
return *this;
// Create some space for the result.
uint64_t * val = new uint64_t[getNumWords()];