Re: [PATCH 3/4] msvc: Fix some compiler warnings

[Junio C Hamano <gitster@pobox.com>]

Ramsay Jones <ramsay@ramsay1.demon.co.uk> 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 <ramsay@ramsay1.demon.co.uk>

I do not think it matters much, but ...

>  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)