------- Comment #7 from rguenth at gcc dot gnu dot org 2006-10-11 12:23 -------
We're not folding
return (int) *((char *) (long unsigned int) i + &a + 1B) + (int) *((char *)
(long unsigned int) i + &b + 1B);
one reason is that the C frontend decomposes &a[i], one is the array-to-pointer
decay code of the frontend. Compare that to the C++ frontend where we manage
to fold to
return <retval> = (int) a[(<unnamed type>) (long unsigned int) i + 1] + (int)
b[(<unnamed type>) (long unsigned int) i + 1];
and so do the optimization.
In particular, fold-const.c:try_move_mult_to_index does not recognize
<addr_expr 0x2b0bb95fd0c0
type <pointer_type 0x2b0bb9615420
type <integer_type 0x2b0bb96022c0 char public string-flag QI
size <integer_cst 0x2b0bb95f27e0 constant invariant 8>
unit size <integer_cst 0x2b0bb95f2810 constant invariant 1>
align 8 symtab 0 alias set -1 precision 8 min <integer_cst
0x2b0bb95f28a0 -128> max <integer_cst 0x2b0bb95f2960 127>
pointer_to_this <pointer_type 0x2b0bb9615420>>
public unsigned DI
size <integer_cst 0x2b0bb95f2d80 constant invariant 64>
unit size <integer_cst 0x2b0bb95f2db0 constant invariant 8>
align 64 symtab 0 alias set -1>
constant invariant
arg 0 <var_decl 0x2b0bb97bcbb0 a
type <array_type 0x2b0bb97bcb00 type <integer_type 0x2b0bb96022c0 char>
BLK
size <integer_cst 0x2b0bb97ce3f0 constant invariant 80>
unit size <integer_cst 0x2b0bb97ce390 constant invariant 10>
align 8 symtab 0 alias set -1 domain <integer_type 0x2b0bb97bca50>>
addressable used public static common BLK defer-output file t.i line 1
size <integer_cst 0x2b0bb97ce3f0 80> unit size <integer_cst 0x2b0bb97ce390 10>
align 8>>
as &a[0].
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|rtl-optimization |c
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28940
