------- Comment #4 from ebotcazou at gcc dot gnu dot org 2008-12-17 17:35
-------
Vlad, I'd again need your help for this one, it's apparently a stack slot
sharing problem. Ada testcase and instructions have been filed.
The problematic excerpt of assembly is:
movl %esi, -28(%ebp) #, %sfp -28(%ebp) <--- tfirst_fpad
subl $1, %esi #, q__move__B_4__L_5__T90b___U
cmpl %esi, %eax # q__move__B_4__L_5__T90b___U, i
jg .L53 #,
movzbl -57(%ebp), %ebx # %sfp,
movl -36(%ebp), %esi # %sfp,
movb %bl, (%esi) #,
je .L53 #,
leal 1(%eax), %ebx #,
addl $1, %esi #, ivtmp.268
movl %ecx, -52(%ebp) # j, %sfp
movl %ebx, %ecx #, ivtmp.266
movzbl -57(%ebp), %ebx # %sfp,
movl %edi, -48(%ebp) # prephitmp.345, %sfp
movl -28(%ebp), %edi # %sfp, tfirst_fpad
movl %eax, -44(%ebp) # i, %sfp
movl %esi, %eax # ivtmp.268, ivtmp.268
movl %edx, %esi # tlast.59, tlast.59
movb %bl, -40(%ebp) #, %sfp
movl -64(%ebp), %ebx # %sfp, source
movzbl -40(%ebp), %edx # %sfp, pad
.p2align 4,,7
.p2align 3
.L54:
addl $1, %ecx #, ivtmp.266
movb %dl, (%eax) # pad,* ivtmp.268
addl $1, %eax #, ivtmp.268
cmpl %edi, %ecx # tfirst_fpad, ivtmp.266
jne .L54 #,
movb %dl, -28(%ebp) # pad, %sfp -28(%ebp) <--- pad
movl -48(%ebp), %edi # %sfp, prephitmp.345
movl %esi, %edx # tlast.59, tlast.59
movl %ebx, -64(%ebp) # source, %sfp
movzbl -28(%ebp), %ebx # %sfp,
movl -52(%ebp), %ecx # %sfp, j
movl -44(%ebp), %eax # %sfp, i
movb %bl, -57(%ebp) #, %sfp
.L53:
movl -28(%ebp), %esi # %sfp, -28(%ebp) ---> tfirst_fpad
The shared slot is -28(%ebp) and the second line with the <--- overwrites the
value written by the first <--- line, which is needed by the ---> line.
If you change the second line to make it use -57(%ebp), with proper reloading
a few lines below, the test passes.
The problematic insn is
insn 1086 1085 1087 127 (set (mem/c:QI (plus:SI (reg/f:SI 6 bp)
(const_int -28 [0xffffffe4])) [13 %sfp+-4 S1 A32])
(reg/v:QI 1 dx [orig:192 pad ] [192])) 50 {*movqi_1} (nil))
which originally was
(insn 1086 0 0 (set (reg/v:QI 452 [orig:192 pad ] [192])
(reg/v:QI 344 [orig:192 pad ] [192])) -1 (nil))
so the problematic pseudo seems to be 452:
scanning new insn with uid = 1082.
Creating newreg=452 from oldreg=192
Creating temporary allocno a379r452
and I'm under the impression that it's wrongly coalesced to pseudo 275:
Coalescing spilled allocnos a379r452->a39r275
--
ebotcazou at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |vmakarov at redhat dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38495
