fabi/Snappy
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add "cc" clobbers to inline asm that modifies flags.

Browse Source 
As far as we know, the lack of "cc" in the clobbers hasn't caused
problems yet, but it could.  This change is to improve correctness,
and is also almost certainly performance neutral.

PiperOrigin-RevId: 487133620
This commit is contained in:
Snappy Team
2022-11-09 05:32:52 +00:00
committed by Victor Costan
parent 8881ba172a
commit 15e2a0e13d
2 changed files with 6 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
snappy-internal.h
View File

@@ -246,7 +246,8 @@ static inline std::pair<size_t, bool> FindMatchLength(const char* s1,
asm("testl %k2, %k2\n\t"
"cmovzq %1, %0\n\t"
: "+r"(a2)
: "r"(a3), "r"(xorval));
: "r"(a3), "r"(xorval)
: "cc");
#endif
*data = a2 >> (shift & (3 * 8));
return std::pair<size_t, bool>(matched_bytes, true);
@@ -277,7 +278,8 @@ static inline std::pair<size_t, bool> FindMatchLength(const char* s1,
asm("testl %k2, %k2\n\t"
"cmovzq %1, %0\n\t"
: "+r"(a2)
: "r"(a3), "r"(xorval));
: "r"(a3), "r"(xorval)
: "cc");
#endif
*data = a2 >> (shift & (3 * 8));
matched += matched_bytes;