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[Bug rtl-optimization/21329] optimize i386 block copy
- From: "vda at port dot imtp dot ilyichevsk dot odessa dot ua" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 2 May 2005 09:10:49 -0000
- Subject: [Bug rtl-optimization/21329] optimize i386 block copy
- References: <20050502085919.21329.vda@port.imtp.ilyichevsk.odessa.ua>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-05-02 09:10 -------
BTW, see above comment: gcc -O2 allocated 24 bytes on stack
and never uset them. ?!
Now, unoptimized compilation comparison:
--- t.s Mon May 2 11:41:20 2005
+++ t-new.s Mon May 2 11:39:40 2005
@@ -32,8 +32,8 @@
movl $t21, %edi
movl $w21, %esi
cld
- movl $9, %ecx
- rep
+ movsl
+ movsl
movsb
popl %esi
popl %edi
@@ -50,9 +50,9 @@
movl $t22, %edi
movl $w22, %esi
cld
- movl $10, %ecx
- rep
- movsb
+ movsl
+ movsl
+ movsw
popl %esi
popl %edi
leave
@@ -68,8 +68,9 @@
movl $t23, %edi
movl $w23, %esi
cld
- movl $11, %ecx
- rep
+ movsl
+ movsl
+ movsw
movsb
popl %esi
popl %edi
@@ -86,9 +87,8 @@
movl $t30, %edi
movl $w30, %esi
cld
- movl $3, %eax
- movl %eax, %ecx
- rep
+ movsl
+ movsl
movsl
popl %esi
popl %edi
@@ -105,9 +105,9 @@
movl $t40, %edi
movl $w40, %esi
cld
- movl $4, %eax
- movl %eax, %ecx
- rep
+ movsl
+ movsl
+ movsl
movsl
popl %esi
popl %edi
@@ -168,34 +168,34 @@
movl $t21, %edi
movl $w21, %esi
cld
- movl $9, %ecx
- rep
+ movsl
+ movsl
movsb
movl $t22, %edi
movl $w22, %esi
cld
- movl $10, %ecx
- rep
- movsb
+ movsl
+ movsl
+ movsw
movl $t23, %edi
movl $w23, %esi
cld
- movl $11, %ecx
- rep
+ movsl
+ movsl
+ movsw
movsb
movl $t30, %edi
movl $w30, %esi
cld
- movl $3, %eax
- movl %eax, %ecx
- rep
+ movsl
+ movsl
movsl
movl $t40, %edi
movl $w40, %esi
cld
- movl $4, %eax
- movl %eax, %ecx
- rep
+ movsl
+ movsl
+ movsl
movsl
movl $t50, %edi
movl $w50, %esi
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21329