Hi, this is the 2nd version of the change, mainly addressed Jakub’s comments:
1. Give up the inlining expansion for strcmp/strncmp/memcmp on a target where the type of the call has same or narrower presicion than unsigned char. 2. add conversions before expand_simple_binop to the two operands. and 3. also updated comments of routine inline_string_cmp to reflect the conversions in the expanded code. have tested on X86 and aarch64. No regressions. Okay for thunk? Qing gcc/ChangeLog: +2018-07-20 Qing Zhao <qing.z...@oracle.com> + + * builtins.c (expand_builtin_memcmp): Delete the last parameter for + call to inline_expand_builtin_string_cmp. + (expand_builtin_strcmp): Likewise. + (expand_builtin_strncmp): Likewise. + (inline_string_cmp): Delete the last parameter, change char_type_node + to unsigned_char_type_node for strcmp/strncmp, add conversions to the + two operands. + (inline_expand_builtin_string_cmp): Delete the last parameter, give up + the inlining expansion on target where the type of the call has same or + narrower presicion than unsigned char. +
78809C_uchar.patch
Description: Binary data
> On Jul 19, 2018, at 12:31 PM, Jakub Jelinek <ja...@redhat.com> wrote: > > If you expand it as (int) ((unsigned char *)p)[n] - (int) ((unsigned char > *)q)[n] > then aren't you relying on int type to have wider precision than unsigned char > (or unit_mode being narrower than mode)? I don't see anywhere where you'd > give up on doing the inline expansion on targets where e.g. lowest > addressable unit would be 16-bit and int would be 16-bit too. > On targets where int is as wide as char, one would need to expand it instead > as something like: > if (((unsigned char *)p)[n] == ((unsigned char *)q)[n]) loop; > ret = ((unsigned char *)p)[n] < ((unsigned char *)q)[n] ? -1 : 1; > or similar or just use the library routine. > > Also: > var_rtx > = adjust_address (var_rtx_array, TYPE_MODE (unit_type_node), offset); > const_rtx = c_readstr (const_str + offset, unit_mode); > rtx op0 = (const_str_n == 1) ? const_rtx : var_rtx; > rtx op1 = (const_str_n == 1) ? var_rtx : const_rtx; > > result = expand_simple_binop (mode, MINUS, op0, op1, > result, is_memcmp ? 1 : 0, OPTAB_WIDEN); > doesn't look correct to me, var_rtx and const_rtx here are in unit_mode, > you need to convert those to mode before you can use those in > expand_simple_binop, using > op0 = convert_modes (mode, unit_mode, op0, 1); > op1 = convert_modes (mode, unit_mode, op1, 1); > before the expand_simple_binop. > While expand_simple_binop is called with an unsignedp argument, that is > meant for the cases where the expansion needs to widen it further, not for > calling expand_simple_binop with arguments with known incorrect mode; > furthermore, one of them being CONST_INT which has VOIDmode.
