diff options
Diffstat (limited to 'sysdeps/i386/i586/strcpy.S')
| -rw-r--r-- | sysdeps/i386/i586/strcpy.S | 62 |
1 files changed, 45 insertions, 17 deletions
diff --git a/sysdeps/i386/i586/strcpy.S b/sysdeps/i386/i586/strcpy.S index a444604f4f..93842429da 100644 --- a/sysdeps/i386/i586/strcpy.S +++ b/sysdeps/i386/i586/strcpy.S @@ -29,6 +29,34 @@ # define STRCPY strcpy #endif +#ifdef PIC +# define JMPTBL(I, B) I - B + +/* Load an entry in a jump table into EDX and branch to it. TABLE is a + jump table with relative offsets. INDEX is a register contains the + index into the jump table. SCALE is the scale of INDEX. */ + +# define BRANCH_TO_JMPTBL_ENTRY(TABLE, INDEX, SCALE) \ + /* We first load PC into EDX. */ \ + SETUP_PIC_REG(dx); \ + /* Get the address of the jump table. */ \ + addl $(TABLE - .), %edx; \ + /* Get the entry and convert the relative offset to the \ + absolute address. */ \ + addl (%edx,INDEX,SCALE), %edx; \ + /* We loaded the jump table and adjusted EDX. Go. */ \ + jmp *%edx +#else +# define JMPTBL(I, B) I + +/* Branch to an entry in a jump table. TABLE is a jump table with + absolute offsets. INDEX is a register contains the index into the + jump table. SCALE is the scale of INDEX. */ + +# define BRANCH_TO_JMPTBL_ENTRY(TABLE, INDEX, SCALE) \ + jmp *TABLE(,INDEX,SCALE) +#endif + #define magic 0xfefefeff .text @@ -53,41 +81,32 @@ ENTRY (STRCPY) cfi_rel_offset (ebx, 0) andl $3, %ecx -#ifdef PIC - call 2f - cfi_adjust_cfa_offset (4) -2: popl %edx - cfi_adjust_cfa_offset (-4) - /* 0xb is the distance between 2: and 1: but we avoid writing - 1f-2b because the assembler generates worse code. */ - leal 0xb(%edx,%ecx,8), %ecx -#else - leal 1f(,%ecx,8), %ecx -#endif - - jmp *%ecx + BRANCH_TO_JMPTBL_ENTRY (L(SrcTable), %ecx, 4) - .align 8 -1: + .p2align 4 +L(Src0): orb (%esi), %al jz L(end) stosb xorl %eax, %eax incl %esi +L(Src1): orb (%esi), %al jz L(end) stosb xorl %eax, %eax incl %esi +L(Src2): orb (%esi), %al jz L(end) stosb xorl %eax, %eax incl %esi -L(1): movl (%esi), %ecx +L(Src3): + movl (%esi), %ecx leal 4(%esi),%esi subl %ecx, %eax @@ -107,7 +126,7 @@ L(1): movl (%esi), %ecx movl %edx, (%edi) leal 4(%edi),%edi - jmp L(1) + jmp L(Src3) L(3): movl %ecx, %edx @@ -164,6 +183,15 @@ L(end2): ret END (STRCPY) + + .p2align 2 + .section .rodata +L(SrcTable): + .int JMPTBL (L(Src0), L(SrcTable)) + .int JMPTBL (L(Src1), L(SrcTable)) + .int JMPTBL (L(Src2), L(SrcTable)) + .int JMPTBL (L(Src3), L(SrcTable)) + #ifndef USE_AS_STPCPY libc_hidden_builtin_def (strcpy) #endif |