Hi,
Could a gatekeeper please help review the fix for bug974(
https://bugs.open64.net/show_bug.cgi?id=974)?
This is a code-size issue, however, we can't ignore the slightly behavior
difference compared to GCC, that will break the link for opencc's build
kernel 3.0.x.
A cut-down case below:
int a[17]={1,2,3};
int main(int argc, char* argv[]){
a[3] = 5;
return a[3];
}
opencc secalign.c -o opencc.out
yug@jupiter:~/work/codesize/secalign> objdump -h opencc.out | grep \\.data
24 .data 00000070 0000000000601010 0000000000601010 00001010
2**4
gcc secalign.c -o gcc.out
yug@jupiter:~/work/codesize/secalign> objdump -h gcc.out | grep \\.data
25 .data 00000064 0000000000601020 0000000000601020 00001020
2**5
we get different section size for .data, gcc with(0x64) vs opencc with
(0x70).
Examine the assemble file, we get gcc's dump:
.data
.align 32
.type a, @object
.size a, 68
a:
.long 1
.long 2
.long 3
.zero 56
while opencc's dump:
.section .data
.org 0x0
.align 0
.globl a
.type a, @object
.size a, 68
a: # 0x0
# offset 0
.4byte 1
# offset 4
.4byte 2
# offset 8
.4byte 3
.skip 56
# end of initialization for a
.section .text
.align 4
.section .data
.align 16
we see that gcc's section directive is strictly follwed by the align
directive, it means the assembler switch to the new section and aligned
firstly to make the section
symbol aligned.
while opencc's does not do section align at the beginning, instead, it
aligns sections at the end of assembler,
this makes the section aligned ready for the next file compiling.
Both implementations seem reasonable, but, for the code-size consideration
and also GCC compatibility,
we can switch to align the section when we firstly initialize the section.
Suggested patch:
osprey/be/cg/cgemit.cxx -- 12a31e9..727bdc1 100644
--- a/osprey/be/cg/cgemit.cxx
+++ b/osprey/be/cg/cgemit.cxx
@@ -9995,21 +9995,7 @@ EMT_End_File( void )
Em_End_Section (em_scn[i].scninfo);
}
if (Assembly) {
- UINT32 tmp, power;
- power = 0;
- for (tmp = STB_align(sym); tmp > 1; tmp >>= 1) power++;
-#if defined(BUILD_OS_DARWIN)
- emit_section_directive(sym);
-#else
- fprintf (Asm_File, "\t%s %s\n", AS_SECTION, ST_name(sym));
-#endif /* defined(BUILD_OS_DARWIN) */
-#ifndef TARG_IA64
-#if defined(TARG_X8664) && ! defined(BUILD_OS_DARWIN)
- fprintf (Asm_File, "\t%s\t%d\n", AS_ALIGN, 1 << power );
-#else
- fprintf (Asm_File, "\t%s\t%d\n", AS_ALIGN, power);
-#endif
-#else
+#ifdef TARG_IA64
ASM_DIR_ALIGN(power, sym);
#endif
}
osprey/be/cg/x8664/cgemit_targ.cxx -- fe6b994..f0eeda2 100644
--- a/osprey/be/cg/x8664/cgemit_targ.cxx
+++ b/osprey/be/cg/x8664/cgemit_targ.cxx
@@ -134,12 +134,6 @@ CGEMIT_Targ_Text_Finalize (ST *pu)
}
-BOOL
-CGEMIT_Align_Section_Once (const char *scn_name)
-{
- return strcmp(scn_name, ".literal") && strcmp(scn_name, ".text");
-}
-
void
CGEMIT_Prn_File_Dir_In_Asm(USRCPOS usrcpos,
const char *pathname,
@@ -312,8 +306,12 @@ CGEMIT_Prn_Scn_In_Asm (FILE *asm_file,
place/align all data items relative to the start of the
section. But some we always align. */
- if (!CGEMIT_Align_Section_Once(scn_name))
- fprintf (asm_file, "\t%s\t%d\n", AS_ALIGN, scn_align);
+#ifdef BUILD_OS_DARWIN
+ fprintf (asm_file, "\t%s\t%d\n", AS_ALIGN, scn_align);
+#else
+ fprintf (asm_file, "\t%s\t%d\n", AS_ALIGN, 1 << scn_align);
+#endif
+
#if defined(BUILD_OS_DARWIN)
/* Darwin "as" doesn't automatically define the section name to be a
symbol
Regards
Gang
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