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| author | Mike Frysinger <vapier@gentoo.org> | 2012-07-31 09:02:35 +0000 |
|---|---|---|
| committer | Mike Frysinger <vapier@gentoo.org> | 2012-07-31 09:02:35 +0000 |
| commit | 902e4335501e73ad45ad2ebc2510b1d41786873f (patch) | |
| tree | 2699b97dd537d8bbf8605c398d4a18106bb55469 /libiberty/md5.c | |
| parent | 4a2608e354d22289f40944bb29d85db3f3c5ca04 (diff) | |
| download | gdb-902e4335501e73ad45ad2ebc2510b1d41786873f.zip gdb-902e4335501e73ad45ad2ebc2510b1d41786873f.tar.gz gdb-902e4335501e73ad45ad2ebc2510b1d41786873f.tar.bz2 | |
libiberty/md5: fix strict alias warnings
Current libiberty md5 code triggers these warnings with gcc-4.7.1 for me:
libiberty/md5.c: In function âmd5_finish_ctxâ:
libiberty/md5.c:117:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
libiberty/md5.c:118:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
The change below fixes things for me. The optimized output (-O2) is the same
before/after my change on x86_64-linux. I imagine it'll be the same for most
targets. It seems simpler than using a union on the md5_ctx buffer since these
are the only two locations in the code where this occurs.
Diffstat (limited to 'libiberty/md5.c')
| -rw-r--r-- | libiberty/md5.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/libiberty/md5.c b/libiberty/md5.c index 0db8fc8..8cc0cb5 100644 --- a/libiberty/md5.c +++ b/libiberty/md5.c @@ -103,6 +103,7 @@ md5_finish_ctx (struct md5_ctx *ctx, void *resbuf) { /* Take yet unprocessed bytes into account. */ md5_uint32 bytes = ctx->buflen; + md5_uint32 swap_bytes; size_t pad; /* Now count remaining bytes. */ @@ -113,10 +114,13 @@ md5_finish_ctx (struct md5_ctx *ctx, void *resbuf) pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes; memcpy (&ctx->buffer[bytes], fillbuf, pad); - /* Put the 64-bit file length in *bits* at the end of the buffer. */ - *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3); - *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) | - (ctx->total[0] >> 29)); + /* Put the 64-bit file length in *bits* at the end of the buffer. + Use memcpy to avoid aliasing problems. On most systems, this + will be optimized away to the same code. */ + swap_bytes = SWAP (ctx->total[0] << 3); + memcpy (&ctx->buffer[bytes + pad], &swap_bytes, sizeof (swap_bytes)); + swap_bytes = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29)); + memcpy (&ctx->buffer[bytes + pad + 4], &swap_bytes, sizeof (swap_bytes)); /* Process last bytes. */ md5_process_block (ctx->buffer, bytes + pad + 8, ctx); |