Re: [Open64-devel] 答复: 答复: 答复: Code review request for bug968: wrong align for variables
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Re: [Open64-devel] 答复: 答复: 答复: Code review request for bug968: wrong align for variables
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From: Sun C. <sun...@gm...> - 2012-04-25 09:29:56
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I was confused by your example. Change the size of test_align to 1,
test_align11 to, say, 19
Sun
On Wed, Apr 25, 2012 at 5:22 PM, zhangliwei <lif...@gm...>wrote:
> ****
>
> Sorry, I can’t agree with you.****
>
> 0x0~0xf ‘ccc’-----------------------------align by 0x10****
>
> 0x800~0xfcf ‘test_align’----------------align by 0x800(2048)****
>
> 0x1000~0x1405 ‘test_align**11’**---------align by 0x400(1024)****
>
> 0x1410~0x144b ‘aaa’--------------------align by 0x10****
>
> 0x1450~0x148b ‘bbb’--------------------align by 0x10****
>
> ** **
>
> ** **
>
> Best wishes,****
>
> Zhangliwei****
> ------------------------------
>
> *发件人:* Sun Chan [mailto:sun...@gm...]
> *发送时间:* **2012年4月25日** 17:09
> *收件人:* zhangliwei
> *抄送:* ope...@li...; Ren Dongchen; shenruifen
> *主题:* Re: 答复: 答复: [Open64-devel] Code review request for bug968: wrong
> align for variables****
>
> ** **
>
> in this example, test_align11 has the wrong alignment, is it?****
>
> Sun****
>
> On Wed, Apr 25, 2012 at 4:59 PM, zhangliwei <lif...@gm...>
> wrote:****
>
> [lwzhang@cario align]$ cat align1.c****
>
> int aaa[15]={0};****
>
> __attribute__((aligned(2048))) unsigned char test_align[2000]={0};****
>
> int bbb[15]={0};****
>
> __attribute__((aligned(1024))) unsigned char test_align11[1030]={0};****
>
> char 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]$ vi align1.s****
>
> ……****
>
> 24 .section .bss****
>
> 25 .org 0x0****
>
> 26 .align 0****
>
> 27 .globl ccc****
>
> 28 .type ccc, @object****
>
> 29 .size ccc, 15****
>
> 30 ccc: # 0x0****
>
> 31 .skip 2048****
>
> 32 .org 0x800****
>
> 33 .align 0****
>
> 34 .globl test_align****
>
> 35 .type test_align, @object****
>
> 36 .size test_align, 2000****
>
> 37 test_align: # 0x800 ****
>
> 38 .skip 2048****
>
> 39 .org 0x1000****
>
> 40 .align 0****
>
> 41 .globl test_align11****
>
> 42 .type test_align11, @object****
>
> 43 .size test_align11, 1030****
>
> 44 test_align11: # 0x1000****
>
> 45 .skip 1040****
>
> 46 .org 0x1410****
>
> 47 .align 0****
>
> 48 .globl aaa****
>
> 49 .type aaa, @object****
>
> 50 .size aaa, 60****
>
> 51 aaa: # 0x1410****
>
> 52 .skip 64****
>
> 53 .org 0x1450****
>
> 54 .align 0****
>
> 55 .globl bbb****
>
> 56 .type bbb, @object****
>
> 57 .size bbb, 60****
>
> 58 bbb: # 0x1450****
>
> 59 .skip 60****
>
> ……****
>
> ****
>
> Best wishes,****
>
> ZhangLiwei****
> ------------------------------
>
> *发件人:* Sun Chan [mailto:sun...@gm...] ****
>
> *发送时间:* **2012年4月25日** 16:48****
>
> *收件人:* zhangliwei
> *抄送:* ope...@li...; Ren Dongchen; shenruifen****
>
> *主题:* Re: 答复: [Open64-devel] Code review request for bug968: wrong align
> for variables ****
>
> ****
>
> suppose you change one of the alignment requirement, say, test_align to,
> say, 2048. And also change ccc to be of type char.****
>
> Can you dump out the alignment for this new example?****
>
> Thx!****
>
> Sun****
>
> On Wed, Apr 25, 2012 at 4:23 PM, zhangliwei <lif...@gm...>
> wrote:****
>
> Sorry. I have sent the mail to wrong receiver.****
>
> Send again:****
>
> Here is the .s file:****
>
> ......****
>
> 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 1040****
>
> 46 .org 0x1010****
>
> 47 .align 0****
>
> 48 .globl aaa****
>
> 49 .type aaa, @object****
>
> 50 .size aaa, 60****
>
> 51 aaa: # 0x1010****
>
> 52 .skip 64****
>
> 53 .org 0x1050****
>
> 54 .align 0****
>
> 55 .globl bbb****
>
> 56 .type bbb, @object****
>
> 57 .size bbb, 60****
>
> 58 bbb: # 0x1050****
>
> 59 .skip 60****
>
> ......****
>
> ****
>
> Best wishes,****
>
> ZhangLiwei****
>
> ****
>
> ****
> ------------------------------
>
> *发件人:* Sun Chan [mailto:sun...@gm...]
> *发送时间:* **2012年4月25日** 16:01
> *收件人:* zhangliwei
> *抄送:* ope...@li...; Ren Dongchen; shenruifen
> *主题:* Re: [Open64-devel] Code review request for bug968: wrong align for
> variables****
>
> ****
>
> can you dump out the .s file after your change?****
>
> Thx!****
>
> Sun****
>
> On Wed, Apr 25, 2012 at 3:07 PM, zhangliwei <lif...@gm...>
> 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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> https://lists.sourceforge.net/lists/listinfo/open64-devel****
>
> ****
>
> ****
>
> ** **
>
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