This change shuffles the code in Simulator::VisitBitfield a bit
to work around a MemorySanitizer bug. New code should not be any
slower or less readable than before.
More info:
https://code.google.com/p/memory-sanitizer/issues/detail?id=50
R=jkummerow@chromium.org
Review URL: https://codereview.chromium.org/
212863002
Patch from Evgeniy Stepanov <eugenis@chromium.org>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20401
ce2b1a6d-e550-0410-aec6-
3dcde31c8c00
// Rotate source bitfield into place.
int64_t result = (static_cast<uint64_t>(src) >> R) | (src << (reg_size - R));
// Determine the sign extension.
- int64_t topbits = ((1L << (reg_size - diff - 1)) - 1) << (diff + 1);
- int64_t signbits = extend && ((src >> S) & 1) ? topbits : 0;
+ int64_t topbits_preshift = (1L << (reg_size - diff - 1)) - 1;
+ int64_t signbits = (extend && ((src >> S) & 1) ? topbits_preshift : 0)
+ << (diff + 1);
// Merge sign extension, dest/zero and bitfield.
result = signbits | (result & mask) | (dst & ~mask);