------- Comment #1 from rguenth at gcc dot gnu dot org 2009-09-23 21:46 -------
So, we have
;; basic block 3, loop depth 1, count 0
;; prev block 2, next block 7
;; pred: 7 [100.0%] (fallthru,dfs_back) 2 [100.0%] (fallthru,exec)
;; succ: 7 [98.5%] (true,exec) 4 [1.5%] (false,exec)
<bb 3>:
# BM_tab_19 = PHI <BM_tab_11(7), &BM_tab[256](2)>
MEM[base: BM_tab_19, offset: 0x0fffffffc] = 6;
MEM[base: BM_tab_19, offset: 0x0fffffff8] = 6;
MEM[base: BM_tab_19, offset: 0x0fffffff4] = 6;
D.2422_17 = (unsigned int) BM_tab_19;
D.2423_18 = D.2422_17 + 0x0fffffff0;
BM_tab_24 = (int *) D.2423_18;
BM_tab_11 = BM_tab_24;
MEM[base: BM_tab_24] = 6;
if (&BM_tab[0] != BM_tab_24)
goto <bb 7>;
else
goto <bb 4>;
;; basic block 7, loop depth 1, count 0
;; prev block 3, next block 4
;; pred: 3 [98.5%] (true,exec)
;; succ: 3 [100.0%] (fallthru,dfs_back)
<bb 7>:
goto <bb 3>;
and for block 7 do
Optimizing block #7
1>>> COND 1 = &BM_tab[0] ne_expr BM_tab_24
1>>> COND 0 = &BM_tab[0] eq_expr BM_tab_24
LKUP STMT D.2422_17 = nop_expr BM_tab_24
D.2422_17 = (unsigned int) BM_tab_24;
LKUP STMT D.2423_18 = D.2422_17 plus_expr 0x0fffffff0
D.2423_18 = D.2422_17 + 0x0fffffff0;
FIND: D.2423_18
LKUP STMT BM_tab_24 = nop_expr D.2423_18
BM_tab_24 = (int *) D.2423_18;
FIND: BM_tab_24
LKUP STMT &BM_tab[0] ne_expr BM_tab_24
if (&BM_tab[0] != BM_tab_24)
FIND: 1
oops. And we jump-thread into an endless loop.
How is this supposed to work?
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41454
