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Remove inline assembly as the bug in clang was fixed

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PiperOrigin-RevId: 387356237
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Snappy Team
2021-07-28 15:32:22 +00:00
committed by Victor Costan
parent 9cc3689b21
commit c8f7641646
1 changed files with 0 additions and 16 deletions
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snappy.cc
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@@ -1141,22 +1141,6 @@ std::pair<const uint8_t*, ptrdiff_t> DecompressBranchless(
} }
std::ptrdiff_t delta = op + len_min_offset - len; std::ptrdiff_t delta = op + len_min_offset - len;
if (SNAPPY_PREDICT_FALSE(delta < 0)) { if (SNAPPY_PREDICT_FALSE(delta < 0)) {
#if defined(__GNUC__) && defined(__x86_64__)
// TODO
// When validating, both code path reduced to `op += len`. Ie. this
// becomes effectively
//
// if (delta < 0) if (tag_type != 0) goto break_loop;
// op += len;
//
// The compiler interchanges the predictable and almost always false
// first if-statement with the completely unpredictable second
// if-statement, putting an unpredictable branch on every iteration.
// This empty asm is worth almost 2x, which I think qualifies for an
// award for the most load-bearing empty statement.
asm("");
#endif
// Due to the spurious offset in literals have this will trigger // Due to the spurious offset in literals have this will trigger
// at the start of a block when op is still smaller than 256. // at the start of a block when op is still smaller than 256.
if (tag_type != 0) goto break_loop; if (tag_type != 0) goto break_loop;