[Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc

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* [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc
@ 2012-10-31  5:39 hjl.tools at gmail dot com
  2012-10-31 10:27 ` [Bug target/55145] " rguenth at gcc dot gnu.org
                   ` (13 more replies)
  0 siblings, 14 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-10-31  5:39 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

             Bug #: 55145
           Summary: [4.8 Regression] [x32] -maddress-mode=long miscompiles
                    glibc
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com
                CC: ubizjak@gmail.com


After fixing PR 55142, GCC 4.8 revision 193001 miscompiles
glibc trunk for x32 with -maddress-mode=long.  Most glibc
tests failed with "Segmentation fault".  It is independent
of LRA and may have something to do with recent subreg
changes.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug target/55145] [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
@ 2012-10-31 10:27 ` rguenth at gcc dot gnu.org
  2012-11-01 10:09 ` ubizjak at gmail dot com
                   ` (12 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-10-31 10:27 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.8.0


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug target/55145] [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
  2012-10-31 10:27 ` [Bug target/55145] " rguenth at gcc dot gnu.org
@ 2012-11-01 10:09 ` ubizjak at gmail dot com
  2012-11-01 22:29 ` hjl.tools at gmail dot com
                   ` (11 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: ubizjak at gmail dot com @ 2012-11-01 10:09 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Uros Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2012-11-01
     Ever Confirmed|0                           |1

--- Comment #1 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-01 10:08:50 UTC ---
So is this PR a manifestation of presumably wrong fix for PR 55142 or an
independent bug?


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug target/55145] [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
  2012-10-31 10:27 ` [Bug target/55145] " rguenth at gcc dot gnu.org
  2012-11-01 10:09 ` ubizjak at gmail dot com
@ 2012-11-01 22:29 ` hjl.tools at gmail dot com
  2012-11-04  8:11 ` [Bug middle-end/55145] Different bits for long double constant depending ptr_mode hjl.tools at gmail dot com
                   ` (10 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-11-01 22:29 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-01 22:29:22 UTC ---
I don't know if there are other bugs in addition to PR 55142.
I will leave it open until I can compile glibc to verify.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending ptr_mode
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (2 preceding siblings ...)
  2012-11-01 22:29 ` hjl.tools at gmail dot com
@ 2012-11-04  8:11 ` hjl.tools at gmail dot com
  2012-11-04 10:14 ` [Bug middle-end/55145] Different bits for long double constant depending on long int size hjl.tools at gmail dot com
                   ` (9 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-11-04  8:11 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |middle-end
            Summary|[4.8 Regression] [x32]      |Different bits for long
                   |-maddress-mode=long         |double constant depending
                   |miscompiles glibc           |ptr_mode

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-04 08:11:01 UTC ---
GCC i386 and GCC x86-64 generate different bits long double constant
depending ptr_mode:

[hjl@gnu-tools-1 tmp]$ cat y.c
const long double
 pio2_hi = 1.5707963267948966192021943710788178805159986950457096099853515625L;
[hjl@gnu-tools-1 tmp]$ /usr/gcc-4.7.3-32bit/bin/gcc -S y.c -o 32.s
[hjl@gnu-tools-1 tmp]$ gcc -S y.c -o 64.s
[hjl@gnu-tools-1 tmp]$ diff -up 64.s 32.s
--- 64.s    2012-11-04 01:06:52.492398183 -0700
+++ 32.s    2012-11-04 01:06:47.685344002 -0700
@@ -3,11 +3,10 @@
     .section    .rodata
     .align 16
     .type    pio2_hi, @object
-    .size    pio2_hi, 16
+    .size    pio2_hi, 12
 pio2_hi:
-    .long    560513588
-    .long    3373259426
+    .long    560513589
+    .long    -921707870
     .long    16383
-    .long    0
-    .ident    "GCC: (GNU) 4.7.2 20120921 (Red Hat 4.7.2-2)"
+    .ident    "GCC: (GNU) 4.7.3 20121024 (prerelease)"
     .section    .note.GNU-stack,"",@progbits
[hjl@gnu-tools-1 tmp]$ gcc -c 32.s 64.s
[hjl@gnu-tools-1 tmp]$ objdump -s -j .rodata 32.o > 32
[hjl@gnu-tools-1 tmp]$ objdump -s -j .rodata 64.o > 64
[hjl@gnu-tools-1 tmp]$ diff -up 32 64
--- 32    2012-11-04 01:07:37.341913094 -0700
+++ 64    2012-11-04 01:07:42.192979572 -0700
@@ -1,5 +1,5 @@

-32.o:     file format elf64-x86-64
+64.o:     file format elf64-x86-64

 Contents of section .rodata:
- 0000 35c26821 a2da0fc9 ff3f0000           5.h!.....?..    
+ 0000 34c26821 a2da0fc9 ff3f0000 00000000  4.h!.....?......
[hjl@gnu-tools-1 tmp]$ 

Ignore padding, i386 GCC generates 35c26821 and
x86-64 generates 34c26821.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (3 preceding siblings ...)
  2012-11-04  8:11 ` [Bug middle-end/55145] Different bits for long double constant depending ptr_mode hjl.tools at gmail dot com
@ 2012-11-04 10:14 ` hjl.tools at gmail dot com
  2012-11-04 11:04 ` schwab@linux-m68k.org
                   ` (8 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-11-04 10:14 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-04 10:14:07 UTC ---
It is due to long int usage in real.h. Depending on
size of long int, real.c gives slightly different
results.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (4 preceding siblings ...)
  2012-11-04 10:14 ` [Bug middle-end/55145] Different bits for long double constant depending on long int size hjl.tools at gmail dot com
@ 2012-11-04 11:04 ` schwab@linux-m68k.org
  2012-11-04 11:09 ` hjl.tools at gmail dot com
                   ` (7 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: schwab@linux-m68k.org @ 2012-11-04 11:04 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

--- Comment #5 from Andreas Schwab <schwab@linux-m68k.org> 2012-11-04 11:04:03 UTC ---
This cannot explain the crashes you see since the difference is just one ULP.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (5 preceding siblings ...)
  2012-11-04 11:04 ` schwab@linux-m68k.org
@ 2012-11-04 11:09 ` hjl.tools at gmail dot com
  2012-11-04 22:52 ` hjl.tools at gmail dot com
                   ` (6 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-11-04 11:09 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-04 11:09:12 UTC ---
(In reply to comment #5)
> This cannot explain the crashes you see since the difference is just one ULP.

The glibc crash is fixed by

http://gcc.gnu.org/ml/gcc-patches/2012-11/msg00248.html


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (6 preceding siblings ...)
  2012-11-04 11:09 ` hjl.tools at gmail dot com
@ 2012-11-04 22:52 ` hjl.tools at gmail dot com
  2012-11-04 23:43 ` vincent-gcc at vinc17 dot net
                   ` (5 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: hjl.tools at gmail dot com @ 2012-11-04 22:52 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-04 22:51:46 UTC ---
Here are different internal values from the same input:

32-bit long: 1.57079632679489661925640447970309310221637133509
Input:       1.5707963267948966192021943710788178805159986950457096099853515625
64-bit long: 1.57079632679489661914798426245454265881562605500221252441

Input value is extremely close to a half-way value between 32-bit
and 64-bit longs.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (7 preceding siblings ...)
  2012-11-04 22:52 ` hjl.tools at gmail dot com
@ 2012-11-04 23:43 ` vincent-gcc at vinc17 dot net
  2013-03-22 14:45 ` jakub at gcc dot gnu.org
                   ` (4 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: vincent-gcc at vinc17 dot net @ 2012-11-04 23:43 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

--- Comment #8 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> 2012-11-04 23:43:44 UTC ---
(In reply to comment #7)
> Here are different internal values from the same input:
> 
> 32-bit long: 1.57079632679489661925640447970309310221637133509
> Input:       1.5707963267948966192021943710788178805159986950457096099853515625
> 64-bit long: 1.57079632679489661914798426245454265881562605500221252441
> 
> Input value is extremely close to a half-way value between 32-bit
> and 64-bit longs.

1.5707963267948966192021943710788178805159986950457096099853515625 is *exactly*
the 65-bit binary number
1.1001001000011111101101010100010001000010110100011000010001101001, thus
exactly a halfway value between two consecutive long double numbers (for 64-bit
precision):
  1.100100100001111110110101010001000100001011010001100001000110100
and
  1.100100100001111110110101010001000100001011010001100001000110101

I suppose that the difference is due to the fact that the algorithm used in GCC
has not been written to round correctly, and if this algorithm uses variables
of type "long" internally, it is not surprising to get different results on
different architectures (32-bit long and 64-bit long).


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (8 preceding siblings ...)
  2012-11-04 23:43 ` vincent-gcc at vinc17 dot net
@ 2013-03-22 14:45 ` jakub at gcc dot gnu.org
  2013-05-31 10:59 ` jakub at gcc dot gnu.org
                   ` (3 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-03-22 14:45 UTC (permalink / raw)
  To: gcc-bugs


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.0                       |4.8.1

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-22 14:44:28 UTC ---
GCC 4.8.0 is being released, adjusting target milestone.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (9 preceding siblings ...)
  2013-03-22 14:45 ` jakub at gcc dot gnu.org
@ 2013-05-31 10:59 ` jakub at gcc dot gnu.org
  2013-10-16  9:49 ` jakub at gcc dot gnu.org
                   ` (2 subsequent siblings)
  13 siblings, 0 replies; 15+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-05-31 10:59 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.1                       |4.8.2

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.1 has been released.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (10 preceding siblings ...)
  2013-05-31 10:59 ` jakub at gcc dot gnu.org
@ 2013-10-16  9:49 ` jakub at gcc dot gnu.org
  2013-11-20 14:40 ` jsm28 at gcc dot gnu.org
  2013-11-20 14:41 ` jsm28 at gcc dot gnu.org
  13 siblings, 0 replies; 15+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-10-16  9:49 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.2                       |4.8.3

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.2 has been released.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (11 preceding siblings ...)
  2013-10-16  9:49 ` jakub at gcc dot gnu.org
@ 2013-11-20 14:40 ` jsm28 at gcc dot gnu.org
  2013-11-20 14:41 ` jsm28 at gcc dot gnu.org
  13 siblings, 0 replies; 15+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2013-11-20 14:40 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Bug 55145 depends on bug 21718, which changed state.

Bug 21718 Summary: real.c rounding not perfect
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21718

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED


^ permalink raw reply	[flat|nested] 15+ messages in thread

* [Bug middle-end/55145] Different bits for long double constant depending on long int size
  2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
                   ` (12 preceding siblings ...)
  2013-11-20 14:40 ` jsm28 at gcc dot gnu.org
@ 2013-11-20 14:41 ` jsm28 at gcc dot gnu.org
  13 siblings, 0 replies; 15+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2013-11-20 14:41 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55145

Joseph S. Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #12 from Joseph S. Myers <jsm28 at gcc dot gnu.org> ---
Just another instance of bug 21718.

*** This bug has been marked as a duplicate of bug 21718 ***


^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2013-11-20 14:41 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
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2012-10-31  5:39 [Bug target/55145] New: [4.8 Regression] [x32] -maddress-mode=long miscompiles glibc hjl.tools at gmail dot com
2012-10-31 10:27 ` [Bug target/55145] " rguenth at gcc dot gnu.org
2012-11-01 10:09 ` ubizjak at gmail dot com
2012-11-01 22:29 ` hjl.tools at gmail dot com
2012-11-04  8:11 ` [Bug middle-end/55145] Different bits for long double constant depending ptr_mode hjl.tools at gmail dot com
2012-11-04 10:14 ` [Bug middle-end/55145] Different bits for long double constant depending on long int size hjl.tools at gmail dot com
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