On Mon, Jun 21, 2010 at 12:33 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> Hi,
>
> This patch adds 8bit divmov pattern for x86. X86 8bit divide
> instructions return result in AX with
>
> AL <- Quotient
> AH <- Remainder
>
> This patch models it and properly extends quotient. Tested
> on Intel64 with -m64 and -m32.  There are no regressions.
> OK for trunk?
>
> BTW, there is only one divb used in subreg_get_info in
> gcc compilers. The old code is
>
>        movzbl  mode_size(%r13), %edi
>        movzbl  mode_size(%r14), %esi
>        xorl    %edx, %edx
>        movl    %edi, %eax
>        divw    %si
>        testw   %dx, %dx
>        jne     .L1194
>
> The new one is
>
>        movzbl  mode_size(%r13), %edi
>        movl    %edi, %eax
>        divb    mode_size(%r14)
>        movzbl  %ah, %eax
>        testb   %al, %al
>        jne     .L1194
>
> Thanks.
>
>
> H.J.
> ---
> gcc/
>
> 2010-06-21  H.J. Lu  <hongjiu.lu@intel.com>
>
>        PR target/44588
>        * config/i386/i386.md (UNSPEC_MOVQI_EXTZV): New.
>        (any_div_code): Likewise.
>        (extend_code): Likewise.
>        (extract_code): Likewise.
>        (*movqi_extzv_3): Likewise.
>        (*movqi_extzv_3_rex64): Likewise.
>        (*movqi_extzv): Likewise.
>        (<u>divmodqi4): Likewise.
>        (*<u>divqi3): Likewise.
>        (<u>divqi3): Remvoved.
>
> gcc/testsuite/
>
> 2010-06-21  H.J. Lu  <hongjiu.lu@intel.com>
>
>        PR target/44588
>        * gcc.target/i386/umod-1.c: New.
>        * gcc.target/i386/umod-2.c: Likewise.
>        * gcc.target/i386/umod-3.c: Likewise.
>

Here is the updated patch.  It uses UNSPEC to extract
remainder in AH from AL. If we only need quotient, it
will be in AL.  Now we generate:

[hjl@gnu-6 divb]$ cat umod-2.c
extern unsigned char z;

unsigned char
foo (unsigned char x, unsigned char y)
{
  z = x/y;
   return x % y;
}
[hjl@gnu-6 divb]$ make umod-2.s
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -Os -S umod-2.c
[hjl@gnu-6 divb]$ cat umod-2.s
	.file	"umod-2.c"
	.text
.globl foo
	.type	foo, @function
foo:
.LFB0:
	.cfi_startproc
	movzbl	%dil, %eax
	divb	%sil
	movb	%al, z(%rip)
	movzbl	%ah, %eax
	ret

OK for trunk?

Thanks.


-- 
H.J.
---
gcc/

2010-06-22  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/44588
	* config/i386/i386.md (UNSPEC_MOVQI_EXTZH): New.
	(any_div_code): Likewise.
	(extend_code): Likewise.
	(extract_code): Likewise.
	(*movqi_extzh): Likewise.
	(*movqi_extzh_rex64): Likewise.
	(<u>divmodqi4): Likewise.
	(*<u>divqi3): Likewise.
	(<u>divqi3): Remvoved.

gcc/testsuite/

2010-06-22  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/44588
	* gcc.target/i386/umod-1.c: New.
	* gcc.target/i386/umod-2.c: Likewise.
	* gcc.target/i386/umod-3.c: Likewise.