Re: [PATCH 3/4] msvc: Fix some compiler warnings
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:49:00
Ramsay Jones [off-list ref] writes:
In particular, using the normal (or production) compiler warning level (-W3), msvc complains as follows: .../sha1.c(244) : warning C4018: '<' : signed/unsigned mismatch .../sha1.c(270) : warning C4244: 'function' : conversion from \ 'unsigned __int64' to 'unsigned long', possible loss of data .../sha1.c(271) : warning C4244: 'function' : conversion from \ 'unsigned __int64' to 'unsigned long', possible loss of data Note that gcc issues a similar complaint about line 244 when compiling with -Wextra. Signed-off-by: Ramsay Jones <redacted>
I do not think it matters much, but ...
quoted hunk
block-sha1/sha1.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-)diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c index e102856..c0054a0 100644 --- a/block-sha1/sha1.c +++ b/block-sha1/sha1.c@@ -237,13 +237,13 @@ void blk_SHA1_Init(blk_SHA_CTX *ctx) void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len) { - int lenW = ctx->size & 63; + unsigned int lenW = ctx->size & 63; ctx->size += len; /* Read the data into W and process blocks as they get full */ if (lenW) { - int left = 64 - lenW; + unsigned int left = 64 - lenW; if (len < left) left = len; memcpy(lenW + (char *)ctx->W, data, left);
... surprisingly this patch changes the compiler output slightly.
Disassembly of section .text:
0000000000000000 <blk_SHA1_Init>:
...
unsigned int left = 64 - lenW;
11ee: bb 40 00 00 00 mov $0x40,%ebx
11f3: 44 29 f3 sub %r14d,%ebx
if (len < left)
- 11f6: 41 89 df mov %ebx,%r15d
+ 11f6: 4c 63 fb movslq %ebx,%r15
11f9: 4c 39 fd cmp %r15,%rbp
11fc: 73 05 jae 1203 <blk_SHA1_Update+0x53>
left = len;
11fe: 89 eb mov %ebp,%ebx
- 1200: 41 89 ef mov %ebp,%r15d
+ 1200: 4c 63 fd movslq %ebp,%r15
memcpy(lenW + (char *)ctx->W, data, left);
1203: 49 8d 45 1c lea 0x1c(%r13),%rax
- 1207: 44 89 f7 mov %r14d,%edi
+ 1207: 49 63 fe movslq %r14d,%rdi
120a: 4c 89 fa mov %r15,%rdx
120d: 4c 89 e6 mov %r12,%rsi
1210: 48 01 c7 add %rax,%rdi
1213: 48 89 04 24 mov %rax,(%rsp)