can you dump out the .s file after your change?
Thx!
Sun
On Wed, Apr 25, 2012 at 3:07 PM, zhangliwei <lifelong830...@gmail.com>wrote:
> **
>
> Hi,****
>
> could a gatekeeper please help review the fix for bug968? ****
>
> (https://bugs.open64.net/show_bug.cgi?id=968)****
>
> ** **
>
> [lwzhang@cario align]$ cat align1.c****
>
> int aaa[15]={0};****
>
> __attribute__((aligned(1024))) unsigned char test_align[2000]={0};****
>
> int bbb[15]={0};****
>
> __attribute__((aligned(1024))) unsigned char test_align11[1030]={0};****
>
> int ccc[15]={0};****
>
> int main()****
>
> {****
>
> memset(ccc, 0, sizeof(ccc));****
>
> memset(test_align, 0, sizeof(test_align));****
>
> memset(test_align11, 0, sizeof(test_align11));****
>
> }****
>
> ** **
>
> [lwzhang@cario align]$ opencc align1.c -o a1 -keep****
>
> [lwzhang@cario align]$ vi align1.s****
>
> ......****
>
> In align1.s:****
>
> 24 .section .bss****
>
> 25 .org 0x0****
>
> 26 .align 0****
>
> 27 .globl ccc****
>
> 28 .type ccc, @object****
>
> 29 .size ccc, 60****
>
> 30 ccc: # 0x0****
>
> 31 .skip 1024****
>
> 32 .org 0x400****
>
> 33 .align 0****
>
> 34 .globl test_align****
>
> 35 .type test_align, @object****
>
> 36 .size test_align, 2000****
>
> 37 test_align: # 0x400****
>
> 38 .skip 2048****
>
> 39 .org 0xc00****
>
> 40 .align 0****
>
> 41 .globl test_align11****
>
> 42 .type test_align11, @object****
>
> 43 .size test_align11, 1030****
>
> 44 test_align11: # 0xc00****
>
> 45 .skip 2048****
>
> 46 .org 0x1400****
>
> 47 .align 0****
>
> 48 .globl aaa****
>
> 49 .type aaa, @object****
>
> 50 .size aaa, 60****
>
> 51 aaa: # 0x1400****
>
> 52 .skip 64****
>
> 53 .org 0x1440****
>
> 54 .align 0****
>
> 55 .globl bbb****
>
> 56 .type bbb, @object****
>
> 57 .size bbb, 60****
>
> 58 bbb: # 0x1440****
>
> 59 .skip 60****
>
> ......****
>
> ** **
>
> (1)Problem:****
>
> For variable 'aaa': .org 0x1400 that means 'aaa''s align is same with
> the****
>
> last variable 'test_align11' 1024. ****
>
> But 'aaa''s align should be 16, not 1024. So here align for 'aaa' is wrong.
> ****
>
> ** **
>
> (2)Analysis:****
>
> From the source code of open64, I found the reason as follows:****
>
> Data_layout.cxx:****
>
> static void****
>
> Allocate_Space(ST *base, ST *blk, INT32 lpad, INT32 rpad, INT64 maxsize)**
> **
>
> {****
>
> ……****
>
> if (!STB_decrement(base)) {****
>
> old_offset = STB_size(base);****
>
> Set_ST_ofst(blk, ROUNDUP(old_offset + lpad, align));****
>
> Set_STB_size(base, ROUNDUP(ST_ofst(blk) + size + rpad, align));****
>
> }****
>
> else {****
>
> old_offset = STB_size(base);****
>
> /* align object end */****
>
> Set_ST_ofst(blk, ROUNDUP(old_offset + lpad, align)); ****
>
> Set_ST_ofst(blk,****
>
> -(INT64) ROUNDUP(ST_ofst(blk) + size + rpad, align)); /* start */****
>
> Set_STB_size(base, -ST_ofst(blk));****
>
> }****
>
> ……****
>
> }****
>
> For variable ‘test_align**11’**, it’s offset is 0xc00, and the .bss
> size update to 0x1400. Then for ‘aaa’, it’s offset is .bss size, that is
> 0x1400. It’s wrong.****
>
> The reason is that after allocating space for ‘test_align**11’**, .bss
> size update align with current variable’s align. ****
>
> I think it should update by adding current variable’s size without any
> align.****
>
> (3)Patch:****
>
> Index: data_layout.cxx****
>
> ===================================================================****
>
> --- data_layout.cxx (revision 3916)****
>
> +++ data_layout.cxx (working copy)****
>
> @@ -679,12 +679,13 @@****
>
> if (!STB_decrement(base)) {****
>
> old_offset = STB_size(base);****
>
> Set_ST_ofst(blk, ROUNDUP(old_offset + lpad, align));****
>
> - Set_STB_size(base, ROUNDUP(ST_ofst(blk) + size + rpad, align));****
>
> + Set_STB_size(base, ST_ofst(blk) + size + rpad);****
>
> }****
>
> else {****
>
> old_offset = STB_size(base);****
>
> /* align object end */****
>
> - Set_ST_ofst(blk, ROUNDUP(old_offset + lpad, align));****
>
> + /* open64.net bug968: here need not align object end */****
>
> + Set_ST_ofst(blk, old_offset + lpad);****
>
> Set_ST_ofst(blk,****
>
> -(INT64) ROUNDUP(ST_ofst(blk) + size + rpad, align)); /* start */*
> ***
>
> Set_STB_size(base, -ST_ofst(blk));****
>
> ** **
>
> ** **
>
> Best wishes,****
>
> ZhangLiwei****
>
>
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