Why GCC copies vectorized buffers to and from stack ?
Am I doing something wrong ?
===
Compiler:
===
gcc -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --enable-plugin
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic
--host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20080704 (Red Hat 4.1.2-46)
===
Source a.c:
===
typedef int BLOCK512 __attribute__((__vector_size__(512)));
void f (BLOCK512 *d, const BLOCK512 *s0, const BLOCK512 *s1) {
*d = *s0 ^ *s1;
}
===
Command:
===
gcc -O3 a.c -c -o a.o
===
Result (note 3 calls to memcpy):
===
Disassembly of section .text:
0000000000000000 <f>:
0: 41 54 push %r12
2: 49 89 fc mov %rdi,%r12
5: 53 push %rbx
6: 48 89 d3 mov %rdx,%rbx
9: ba 00 02 00 00 mov $0x200,%edx
e: 48 81 ec 08 06 00 00 sub $0x608,%rsp
15: 48 8d bc 24 00 02 00 lea 0x200(%rsp),%rdi
1c: 00
1d: e8 00 00 00 00 callq 22 <f+0x22>
1e: R_X86_64_PC32 memcpy+0xfffffffffffffffc
22: 48 8d bc 24 00 04 00 lea 0x400(%rsp),%rdi
29: 00
2a: 48 89 de mov %rbx,%rsi
2d: ba 00 02 00 00 mov $0x200,%edx
32: e8 00 00 00 00 callq 37 <f+0x37>
33: R_X86_64_PC32 memcpy+0xfffffffffffffffc
37: 66 0f 6f 84 24 00 04 movdqa 0x400(%rsp),%xmm0
3e: 00 00
40: 48 89 e6 mov %rsp,%rsi
43: 4c 89 e7 mov %r12,%rdi
46: ba 00 02 00 00 mov $0x200,%edx
4b: 66 0f ef 84 24 00 02 pxor 0x200(%rsp),%xmm0
52: 00 00
54: 66 0f 7f 04 24 movdqa %xmm0,(%rsp)
59: 66 0f 6f 84 24 10 04 movdqa 0x410(%rsp),%xmm0
60: 00 00
62: 66 0f ef 84 24 10 02 pxor 0x210(%rsp),%xmm0
69: 00 00
6b: 66 0f 7f 44 24 10 movdqa %xmm0,0x10(%rsp)
71: 66 0f 6f 84 24 20 04 movdqa 0x420(%rsp),%xmm0
78: 00 00
7a: 66 0f ef 84 24 20 02 pxor 0x220(%rsp),%xmm0
81: 00 00
83: 66 0f 7f 44 24 20 movdqa %xmm0,0x20(%rsp)
89: 66 0f 6f 84 24 30 04 movdqa 0x430(%rsp),%xmm0
90: 00 00
92: 66 0f ef 84 24 30 02 pxor 0x230(%rsp),%xmm0
99: 00 00
9b: 66 0f 7f 44 24 30 movdqa %xmm0,0x30(%rsp)
a1: 66 0f 6f 84 24 40 04 movdqa 0x440(%rsp),%xmm0
a8: 00 00
aa: 66 0f ef 84 24 40 02 pxor 0x240(%rsp),%xmm0
b1: 00 00
b3: 66 0f 7f 44 24 40 movdqa %xmm0,0x40(%rsp)
b9: 66 0f 6f 84 24 50 04 movdqa 0x450(%rsp),%xmm0
c0: 00 00
c2: 66 0f ef 84 24 50 02 pxor 0x250(%rsp),%xmm0
c9: 00 00
cb: 66 0f 7f 44 24 50 movdqa %xmm0,0x50(%rsp)
d1: 66 0f 6f 84 24 60 04 movdqa 0x460(%rsp),%xmm0
d8: 00 00
da: 66 0f ef 84 24 60 02 pxor 0x260(%rsp),%xmm0
e1: 00 00
e3: 66 0f 7f 44 24 60 movdqa %xmm0,0x60(%rsp)
e9: 66 0f 6f 84 24 70 04 movdqa 0x470(%rsp),%xmm0
f0: 00 00
f2: 66 0f ef 84 24 70 02 pxor 0x270(%rsp),%xmm0
f9: 00 00
fb: 66 0f 7f 44 24 70 movdqa %xmm0,0x70(%rsp)
101: 66 0f 6f 84 24 80 04 movdqa 0x480(%rsp),%xmm0
108: 00 00
10a: 66 0f ef 84 24 80 02 pxor 0x280(%rsp),%xmm0
111: 00 00
113: 66 0f 7f 84 24 80 00 movdqa %xmm0,0x80(%rsp)
11a: 00 00
11c: 66 0f 6f 84 24 90 04 movdqa 0x490(%rsp),%xmm0
123: 00 00
125: 66 0f ef 84 24 90 02 pxor 0x290(%rsp),%xmm0
12c: 00 00
12e: 66 0f 7f 84 24 90 00 movdqa %xmm0,0x90(%rsp)
135: 00 00
137: 66 0f 6f 84 24 a0 04 movdqa 0x4a0(%rsp),%xmm0
13e: 00 00
140: 66 0f ef 84 24 a0 02 pxor 0x2a0(%rsp),%xmm0
147: 00 00
149: 66 0f 7f 84 24 a0 00 movdqa %xmm0,0xa0(%rsp)
150: 00 00
152: 66 0f 6f 84 24 b0 04 movdqa 0x4b0(%rsp),%xmm0
159: 00 00
15b: 66 0f ef 84 24 b0 02 pxor 0x2b0(%rsp),%xmm0
162: 00 00
164: 66 0f 7f 84 24 b0 00 movdqa %xmm0,0xb0(%rsp)
16b: 00 00
16d: 66 0f 6f 84 24 c0 04 movdqa 0x4c0(%rsp),%xmm0
174: 00 00
176: 66 0f ef 84 24 c0 02 pxor 0x2c0(%rsp),%xmm0
17d: 00 00
17f: 66 0f 7f 84 24 c0 00 movdqa %xmm0,0xc0(%rsp)
186: 00 00
188: 66 0f 6f 84 24 d0 04 movdqa 0x4d0(%rsp),%xmm0
18f: 00 00
191: 66 0f ef 84 24 d0 02 pxor 0x2d0(%rsp),%xmm0
198: 00 00
19a: 66 0f 7f 84 24 d0 00 movdqa %xmm0,0xd0(%rsp)
1a1: 00 00
1a3: 66 0f 6f 84 24 e0 04 movdqa 0x4e0(%rsp),%xmm0
1aa: 00 00
1ac: 66 0f ef 84 24 e0 02 pxor 0x2e0(%rsp),%xmm0
1b3: 00 00
1b5: 66 0f 7f 84 24 e0 00 movdqa %xmm0,0xe0(%rsp)
1bc: 00 00
1be: 66 0f 6f 84 24 f0 04 movdqa 0x4f0(%rsp),%xmm0
1c5: 00 00
1c7: 66 0f ef 84 24 f0 02 pxor 0x2f0(%rsp),%xmm0
1ce: 00 00
1d0: 66 0f 7f 84 24 f0 00 movdqa %xmm0,0xf0(%rsp)
1d7: 00 00
1d9: 66 0f 6f 84 24 00 05 movdqa 0x500(%rsp),%xmm0
1e0: 00 00
1e2: 66 0f ef 84 24 00 03 pxor 0x300(%rsp),%xmm0
1e9: 00 00
1eb: 66 0f 7f 84 24 00 01 movdqa %xmm0,0x100(%rsp)
1f2: 00 00
1f4: 66 0f 6f 84 24 10 05 movdqa 0x510(%rsp),%xmm0
1fb: 00 00
1fd: 66 0f ef 84 24 10 03 pxor 0x310(%rsp),%xmm0
204: 00 00
206: 66 0f 7f 84 24 10 01 movdqa %xmm0,0x110(%rsp)
20d: 00 00
20f: 66 0f 6f 84 24 20 05 movdqa 0x520(%rsp),%xmm0
216: 00 00
218: 66 0f ef 84 24 20 03 pxor 0x320(%rsp),%xmm0
21f: 00 00
221: 66 0f 7f 84 24 20 01 movdqa %xmm0,0x120(%rsp)
228: 00 00
22a: 66 0f 6f 84 24 30 05 movdqa 0x530(%rsp),%xmm0
231: 00 00
233: 66 0f ef 84 24 30 03 pxor 0x330(%rsp),%xmm0
23a: 00 00
23c: 66 0f 7f 84 24 30 01 movdqa %xmm0,0x130(%rsp)
243: 00 00
245: 66 0f 6f 84 24 40 05 movdqa 0x540(%rsp),%xmm0
24c: 00 00
24e: 66 0f ef 84 24 40 03 pxor 0x340(%rsp),%xmm0
255: 00 00
257: 66 0f 7f 84 24 40 01 movdqa %xmm0,0x140(%rsp)
25e: 00 00
260: 66 0f 6f 84 24 50 05 movdqa 0x550(%rsp),%xmm0
267: 00 00
269: 66 0f ef 84 24 50 03 pxor 0x350(%rsp),%xmm0
270: 00 00
272: 66 0f 7f 84 24 50 01 movdqa %xmm0,0x150(%rsp)
279: 00 00
27b: 66 0f 6f 84 24 60 05 movdqa 0x560(%rsp),%xmm0
282: 00 00
284: 66 0f ef 84 24 60 03 pxor 0x360(%rsp),%xmm0
28b: 00 00
28d: 66 0f 7f 84 24 60 01 movdqa %xmm0,0x160(%rsp)
294: 00 00
296: 66 0f 6f 84 24 70 05 movdqa 0x570(%rsp),%xmm0
29d: 00 00
29f: 66 0f ef 84 24 70 03 pxor 0x370(%rsp),%xmm0
2a6: 00 00
2a8: 66 0f 7f 84 24 70 01 movdqa %xmm0,0x170(%rsp)
2af: 00 00
2b1: 66 0f 6f 84 24 80 05 movdqa 0x580(%rsp),%xmm0
2b8: 00 00
2ba: 66 0f ef 84 24 80 03 pxor 0x380(%rsp),%xmm0
2c1: 00 00
2c3: 66 0f 7f 84 24 80 01 movdqa %xmm0,0x180(%rsp)
2ca: 00 00
2cc: 66 0f 6f 84 24 90 05 movdqa 0x590(%rsp),%xmm0
2d3: 00 00
2d5: 66 0f ef 84 24 90 03 pxor 0x390(%rsp),%xmm0
2dc: 00 00
2de: 66 0f 7f 84 24 90 01 movdqa %xmm0,0x190(%rsp)
2e5: 00 00
2e7: 66 0f 6f 84 24 a0 05 movdqa 0x5a0(%rsp),%xmm0
2ee: 00 00
2f0: 66 0f ef 84 24 a0 03 pxor 0x3a0(%rsp),%xmm0
2f7: 00 00
2f9: 66 0f 7f 84 24 a0 01 movdqa %xmm0,0x1a0(%rsp)
300: 00 00
302: 66 0f 6f 84 24 b0 05 movdqa 0x5b0(%rsp),%xmm0
309: 00 00
30b: 66 0f ef 84 24 b0 03 pxor 0x3b0(%rsp),%xmm0
312: 00 00
314: 66 0f 7f 84 24 b0 01 movdqa %xmm0,0x1b0(%rsp)
31b: 00 00
31d: 66 0f 6f 84 24 c0 05 movdqa 0x5c0(%rsp),%xmm0
324: 00 00
326: 66 0f ef 84 24 c0 03 pxor 0x3c0(%rsp),%xmm0
32d: 00 00
32f: 66 0f 7f 84 24 c0 01 movdqa %xmm0,0x1c0(%rsp)
336: 00 00
338: 66 0f 6f 84 24 d0 05 movdqa 0x5d0(%rsp),%xmm0
33f: 00 00
341: 66 0f ef 84 24 d0 03 pxor 0x3d0(%rsp),%xmm0
348: 00 00
34a: 66 0f 7f 84 24 d0 01 movdqa %xmm0,0x1d0(%rsp)
351: 00 00
353: 66 0f 6f 84 24 e0 05 movdqa 0x5e0(%rsp),%xmm0
35a: 00 00
35c: 66 0f ef 84 24 e0 03 pxor 0x3e0(%rsp),%xmm0
363: 00 00
365: 66 0f 7f 84 24 e0 01 movdqa %xmm0,0x1e0(%rsp)
36c: 00 00
36e: 66 0f 6f 84 24 f0 05 movdqa 0x5f0(%rsp),%xmm0
375: 00 00
377: 66 0f ef 84 24 f0 03 pxor 0x3f0(%rsp),%xmm0
37e: 00 00
380: 66 0f 7f 84 24 f0 01 movdqa %xmm0,0x1f0(%rsp)
387: 00 00
389: e8 00 00 00 00 callq 38e <f+0x38e>
38a: R_X86_64_PC32 memcpy+0xfffffffffffffffc
38e: 48 81 c4 08 06 00 00 add $0x608,%rsp
395: 5b pop %rbx
396: 41 5c pop %r12
398: c3
--
Summary: long vector operation causes gcc to copy arguments
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: Shvaiger_Felix at emc dot com
GCC build triplet: x86_64-redhat-linux
GCC host triplet: x86_64-redhat-linux
GCC target triplet: x86_64-redhat-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42367
