[Bug target/38902] [4.3 Regression] __builtin_strcpy doesn't work with -fstack-protector

[hjl dot tools at gmail dot com]

------- Comment #10 from hjl dot tools at gmail dot com  2009-01-19 19:30 
-------
The problem is x86 doesn't set the memory size correct for rep_stos.
Gcc 4.3.3 gave:

(gdb) call debug_rtx (destmem)
(mem/s/c:BLK (reg:DI 59) [3 buffer+8 S1 A64])
(gdb) 

Jakub's patch corrected it to

(gdb) call debug_rtx (destmem)
(mem/s/c:BLK (reg:DI 59) [0 buffer+8 S1016 A64])
(gdb) 

Since scheduler thinks the size of memory is 1, it changed

(insn:HI 13 12 15 2 x.c:5 (parallel [
            (set (reg:DI 2 cx [62])
                (const_int 0 [0x0]))
            (set (reg:DI 5 di [59])
                (plus:DI (ashift:DI (reg:DI 2 cx [62])
                        (const_int 3 [0x3]))
                    (reg:DI 5 di [59])))
            (set (mem/s/c:BLK (reg:DI 5 di [59]) [3 buffer+8 S1 A64])
                (const_int 0 [0x0]))
            (use (reg:DI 0 ax [60]))
            (use (reg:DI 2 cx [62]))
        ]) 801 {*rep_stosdi_rex64} (expr_list:REG_DEAD (reg:DI 0 ax [60])
        (expr_list:REG_UNUSED (reg:DI 5 di [59])
            (expr_list:REG_UNUSED (reg:DI 2 cx [62])
                (nil)))))
...
(insn:HI 22 65 24 2 x.c:6 (set (mem/s/c:HI (plus:DI (reg/f:DI 7 sp)
                (const_int 24 [0x18])) [0 buffer+24 S2 A64])
        (const_int 111 [0x6f])) 53 {*movhi_1} (nil)

into

(insn:HI 22 65 24 2 x.c:6 (set (mem/s/c:HI (plus:DI (reg/f:DI 7 sp)
                (const_int 24 [0x18])) [0 buffer+24 S2 A64])
        (const_int 111 [0x6f])) 53 {*movhi_1} (nil)
...
(insn:TI 13 22 68 2 x.c:5 (parallel [
            (set (reg:DI 2 cx [62])
                (const_int 0 [0x0]))
            (set (reg:DI 5 di [59])
                (plus:DI (ashift:DI (reg:DI 2 cx [62])
                        (const_int 3 [0x3]))
                    (reg:DI 5 di [59])))
            (set (mem/s/c:BLK (reg:DI 5 di [59]) [3 buffer+8 S1 A64])
                (const_int 0 [0x0]))
            (use (reg:DI 0 ax [60]))
            (use (reg:DI 2 cx [62]))
        ]) 801 {*rep_stosdi_rex64} (expr_list:REG_DEAD (reg:DI 0 ax [60])
        (expr_list:REG_UNUSED (reg:DI 5 di [59])
            (expr_list:REG_UNUSED (reg:DI 2 cx [62])
                (nil)))))


-- 

hjl dot tools at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38902