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Revert commits r222146 and r222137.

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They were producing the wrong result if NumBits == BitsInWord. The old mask
produced -1, the new mask 0.

This should fix the 32 bit bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222166 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2014-11-17 19:26:40 +00:00
parent 95764ec6ed
commit d5b5eb6c97
1 changed files with 5 additions and 3 deletions
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8
include/llvm/Bitcode/BitstreamReader.h
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@@ -338,14 +338,16 @@ public:
} }
word_t Read(unsigned NumBits) { word_t Read(unsigned NumBits) {
assert(NumBits && NumBits <= sizeof(word_t) * 8 && static const unsigned BitsInWord = sizeof(word_t) * 8;
assert(NumBits && NumBits <= BitsInWord &&
"Cannot return zero or more than BitsInWord bits!"); "Cannot return zero or more than BitsInWord bits!");
static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f; static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
// If the field is fully contained by CurWord, return it quickly. // If the field is fully contained by CurWord, return it quickly.
if (BitsInCurWord >= NumBits) { if (BitsInCurWord >= NumBits) {
word_t R = CurWord & ((word_t(1) << (NumBits & Mask)) - 1); word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
// Use a mask to avoid undefined behavior. // Use a mask to avoid undefined behavior.
CurWord >>= (NumBits & Mask); CurWord >>= (NumBits & Mask);
@@ -363,7 +365,7 @@ public:
if (BitsLeft > BitsInCurWord) if (BitsLeft > BitsInCurWord)
return 0; return 0;
word_t R2 = CurWord & ((word_t(1) << (BitsLeft & Mask)) - 1); word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
// Use a mask to avoid undefined behavior. // Use a mask to avoid undefined behavior.
CurWord >>= (BitsLeft & Mask); CurWord >>= (BitsLeft & Mask);