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* [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c
@ 2006-08-16 5:20 carlos at systemhalted dot org
2006-08-16 5:22 ` [Bug middle-end/28749] " pinskia at gcc dot gnu dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: carlos at systemhalted dot org @ 2006-08-16 5:20 UTC (permalink / raw)
To: gcc-bugs
This is a regression since 4.1 and 4.0 compile vfprintf.c correctly.
I am using gcc trunk to build libc / libc-ports head. I have a regression in
tst-printfsz which is part of the glibc testsuite. The problem is a
miscompilation of glibc/stdio-common/vfprintf.c by GCC.
The bug is as follows:
Location 1 jumps to location 2.
Compiler moves first insn at location 2 to location 1's branch delay slot.
Location 3 computes a goto to location 2.
Because the first insn at location 2 was moved, the program now crashes.
The concrete debugging example:
The first insn "ldil L%4000,r21" is moved to location 1's branch delay slot.
Location 3:
468cc: ea a0 c0 02 bv,n r0(r21)
r21 == (0x403d3000 + 0x4928c) and is part of "goto *ptr"
Location 1:
478b4: 82 9c 93 a4 cmpb,<< ret0,r20,4928c <_IO_vfprintf+0x322c>
478b8: 22 a2 00 00 ldil L%4000,r21
Location 2:
4928c: 36 b5 0a d9 ldo -1a94(r21),r21
49290: 08 75 0a 15 add,l r21,r3,r21
49294: 0e a0 10 95 ldw 0(r21),r21
49298: 92 a0 30 00 cmpiclr,<> 0,r21,r0
4929c: e8 1e 0f 45 b,l 46a44 <_IO_vfprintf+0x9e4>,r0
492a0: 34 15 3f ff ldi -1,r21
The code at location 3 jumps to location 2, and does not execute the required
"ldil L%4000,r21"
The computed goto should create edges to all the label addresses taken by &&,
and that should prevent the branch delay slot from fill from occuring.
I am recompiling glibc with CFLAGS-vfprintf.c += -fno-delayed-branch to see if
it passes the tst-printfsz test.
How should I proceed on this issue? I have tried to create a testcase, but I
haven't been successfull.
--
Summary: Miscompilation of glibc/stdio-common/vfprintf.c
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: carlos at systemhalted dot org
GCC build triplet: hppa-linux
GCC host triplet: hppa-linux
GCC target triplet: hppa-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28749
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c
2006-08-16 5:20 [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c carlos at systemhalted dot org
@ 2006-08-16 5:22 ` pinskia at gcc dot gnu dot org
2006-08-16 5:57 ` [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill carlos at systemhalted dot org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-08-16 5:22 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2006-08-16 05:22 -------
Yes a testcase is needed.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|critical |normal
Status|UNCONFIRMED |WAITING
Component|c |middle-end
Keywords| |wrong-code
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28749
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill.
2006-08-16 5:20 [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c carlos at systemhalted dot org
2006-08-16 5:22 ` [Bug middle-end/28749] " pinskia at gcc dot gnu dot org
@ 2006-08-16 5:57 ` carlos at systemhalted dot org
2006-08-16 6:48 ` carlos at systemhalted dot org
2006-11-15 8:06 ` pinskia at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: carlos at systemhalted dot org @ 2006-08-16 5:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from carlos at systemhalted dot org 2006-08-16 05:56 -------
Building vfprintf.c with -fno-delayed-branch is a workaround.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28749
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill.
2006-08-16 5:20 [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c carlos at systemhalted dot org
2006-08-16 5:22 ` [Bug middle-end/28749] " pinskia at gcc dot gnu dot org
2006-08-16 5:57 ` [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill carlos at systemhalted dot org
@ 2006-08-16 6:48 ` carlos at systemhalted dot org
2006-11-15 8:06 ` pinskia at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: carlos at systemhalted dot org @ 2006-08-16 6:48 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from carlos at systemhalted dot org 2006-08-16 06:48 -------
Dumping vfprintf.c compile with -S and -da
; basic block 131
.LBE379:
.LBB380:
.LBB380:
; vfprintf.c:1448
.loc 2 1448 0
ldw 8(%r3),%r28
ldil L'16384,%r22
ldb 0(%r28),%r21
.LVL339:
ldo -6804(%r22),%r22
extrs %r21,31,8,%r28
addl %r22,%r3,%r22
stw %r28,0(%r22)
ldo -32(%r21),%r20
ldi 90,%r28
extru %r20,31,8,%r20
; vfprintf.c:1562
.loc 2 1562 0
; vfprintf.c:1448
.loc 2 1448 0
comb,<< %r28,%r20,.L1104
ldil L'16384,%r21
^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Incorrect delay slot fill.
; basic block 313
.LVL557:
.L1104:
.LBE425:
.LBE418:
.LBE417:
.LBB426:
; vfprintf.c:1562
.loc 2 1562 0
ldo -6804(%r21),%r21
addl %r21,%r3,%r21
ldw 0(%r21),%r21
bb 313 is missing the first insn.
The output of vfprintf.c.157r.dbr shows:
(barrier 18544 18543 2803)
(note 2803 18544 14801 ("vfprintf.c") 1561)
(note 14801 2803 14802 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5 [orig:281
size ] [281])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14802 14801 14803 ( function_done (nil)) NOTE_INSN_VAR_LOCATION)
(note 14803 14802 14804 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5
[orig:280 size ] [280])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14804 14803 14805 ( __self (expr_list:REG_DEP_TRUE (reg/v/f:SI 5 %r5
[orig:364 __self ] [364])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14805 14804 14806 ( ptr (expr_list:REG_DEP_TRUE (reg/v/f:SI 21 %r21
[orig:346 ptr ] [346])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14806 14805 2804 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5 [orig:282
size ] [282])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(code_label/s 2804 14806 2805 242 ("do_form_unknown") [1 uses])
(note 2805 2804 2806 [bb 313] NOTE_INSN_BASIC_BLOCK)
(note 2806 2805 14807 ("vfprintf.c") 1562)
(note 14807 2806 19223 ( ptr (nil)) NOTE_INSN_VAR_LOCATION)
(code_label 19223 14807 8862 1104 "" [2 uses])
(insn 8862 19223 8863 vfprintf.c:1562 (set (reg/f:SI 21 %r21)
(plus:SI (reg/f:SI 21 %r21)
(const_int -6804 [0xffffe56c]))) 114 {addsi3} (nil)
(expr_list:REG_EQUAL (const_int 9580 [0x256c])
(nil)))
And the set has been moved into bb 131
(insn 19224 831 14145 vfprintf.c:1562 (sequence [
(jump_insn:TI 833 831 8861 vfprintf.c:1448 (set (pc)
(if_then_else (gtu (reg:SI 20 %r20 [782])
(reg:SI 28 %r28 [783]))
(label_ref:SI 19223)
(pc))) -1 (nil)
(expr_list:REG_BR_PRED (const_int 4 [0x4])
(expr_list:REG_DEAD (reg:SI 20 %r20 [782])
(expr_list:REG_DEAD (reg:SI 28 %r28 [783])
(expr_list:REG_EQUAL (if_then_else (gtu (reg:SI 20
%r20 [782])
(const_int 90 [0x5a]))
(label_ref:SI 19223)
(pc))
(expr_list:REG_BR_PROB (const_int 5000
[0x1388])
(nil)))))))
(insn/s:TI 8861 833 14145 (set (reg/f:SI 21 %r21)
(const_int 16384 [0x4000])) 37 {*pa.md:2482} (nil)
(nil))
]) -1 (nil)
(nil))
While vfprintf.c.156r.barriers shows:
(barrier 12266 12265 2803)
(note 2803 12266 14801 ("vfprintf.c") 1561)
(note 14801 2803 14802 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5 [orig:281
size ] [281])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14802 14801 14803 ( function_done (nil)) NOTE_INSN_VAR_LOCATION)
(note 14803 14802 14804 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5
[orig:280 size ] [280])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14804 14803 14805 ( __self (expr_list:REG_DEP_TRUE (reg/v/f:SI 5 %r5
[orig:364 __self ] [364])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14805 14804 14806 ( ptr (expr_list:REG_DEP_TRUE (reg/v/f:SI 21 %r21
[orig:346 ptr ] [346])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(note 14806 14805 2804 ( size (expr_list:REG_DEP_TRUE (reg/v:SI 5 %r5 [orig:282
size ] [282])
(const_int 0 [0x0]))) NOTE_INSN_VAR_LOCATION)
(code_label/s 2804 14806 2805 242 ("do_form_unknown") [5 uses])
(note 2805 2804 2806 [bb 313] NOTE_INSN_BASIC_BLOCK)
(note 2806 2805 8861 ("vfprintf.c") 1562)
(insn:TI 8861 2806 14807 vfprintf.c:1562 (set (reg/f:SI 21 %r21)
(const_int 16384 [0x4000])) 37 {*pa.md:2482} (nil)
(nil))
That is is still present in the correct basic block before dbr, and the label
and barriers are present.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28749
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill.
2006-08-16 5:20 [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c carlos at systemhalted dot org
` (2 preceding siblings ...)
2006-08-16 6:48 ` carlos at systemhalted dot org
@ 2006-11-15 8:06 ` pinskia at gcc dot gnu dot org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-11-15 8:06 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2006-11-15 08:06 -------
No testcase in 3 months so closing.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28749
^ permalink raw reply [flat|nested] 5+ messages in thread
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2006-08-16 5:20 [Bug c/28749] New: Miscompilation of glibc/stdio-common/vfprintf.c carlos at systemhalted dot org
2006-08-16 5:22 ` [Bug middle-end/28749] " pinskia at gcc dot gnu dot org
2006-08-16 5:57 ` [Bug middle-end/28749] Miscompilation of glibc/stdio-common/vfprintf.c, invalid delay slot fill carlos at systemhalted dot org
2006-08-16 6:48 ` carlos at systemhalted dot org
2006-11-15 8:06 ` pinskia at gcc dot gnu dot org
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