https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61190
Bug ID: 61190
Summary: [4.8/4.9/4.10 Regression]
g++.old-deja/g++.mike/p4736b.C FAILs at -O2/-Os/-O3
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Created attachment 32798
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32798&action=edit
prep
Valgrind output with various GCC versions:
$ g++-trunk-r210412 -O2 p4736b.ii
$ valgrind -q --track-origins=yes ./a.out
==11986== Use of uninitialised value of size 8
==11986== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==11986== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==11986== Uninitialised value was created by a stack allocation
==11986== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==11986==
==11986== Invalid read of size 8
==11986== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==11986== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==11986== Address 0xffffffffffffffe8 is not stack'd, malloc'd or (recently)
free'd
==11986==
==11986==
==11986== Process terminating with default action of signal 11 (SIGSEGV)
==11986== Access not within mapped region at address 0xFFFFFFFFFFFFFFE8
==11986== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==11986== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
$ g++-4_9-r210307 -O2 p4736b.ii
$ valgrind -q --track-origins=yes ./a.out
==12013== Use of uninitialised value of size 8
==12013== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12013== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==12013== Uninitialised value was created by a stack allocation
==12013== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12013==
==12013== Invalid read of size 8
==12013== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12013== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==12013== Address 0xffffffffffffffe8 is not stack'd, malloc'd or (recently)
free'd
==12013==
==12013==
==12013== Process terminating with default action of signal 11 (SIGSEGV)
==12013== Access not within mapped region at address 0xFFFFFFFFFFFFFFE8
==12013== at 0x4006F3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12013== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
$ g++-4_8-r210303 -O2 p4736b.ii
$ valgrind -q --track-origins=yes ./a.out
==12047== Use of uninitialised value of size 8
==12047== at 0x4006C3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12047== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==12047== Uninitialised value was created by a stack allocation
==12047== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12047==
==12047== Invalid read of size 8
==12047== at 0x4006C3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12047== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
==12047== Address 0xffffffffffffffe8 is not stack'd, malloc'd or (recently)
free'd
==12047==
==12047==
==12047== Process terminating with default action of signal 11 (SIGSEGV)
==12047== Access not within mapped region at address 0xFFFFFFFFFFFFFFE8
==12047== at 0x4006C3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12047== by 0x400517: main (in /home/smatz/gcc-bug/1256/a.out)
$ g++-4_7-r210302 -O2 p4736b.ii
$ valgrind -q --track-origins=yes ./a.out
==12072== Use of uninitialised value of size 8
==12072== at 0x4006C3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12072== by 0x400511: main (in /home/smatz/gcc-bug/1256/a.out)
==12072== Uninitialised value was created by a stack allocation
==12072== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12072==
==12072== Use of uninitialised value of size 8
==12072== at 0x4006C3: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12072== by 0x40052B: main (in /home/smatz/gcc-bug/1256/a.out)
==12072== Uninitialised value was created by a stack allocation
==12072== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12072==
==12072== Use of uninitialised value of size 8
==12072== at 0x4006D7: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12072== by 0x40053F: main (in /home/smatz/gcc-bug/1256/a.out)
==12072== Uninitialised value was created by a stack allocation
==12072== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12072==
==12072== Use of uninitialised value of size 8
==12072== at 0x4006E7: virtual thunk to Main::foo() (in
/home/smatz/gcc-bug/1256/a.out)
==12072== by 0x400553: main (in /home/smatz/gcc-bug/1256/a.out)
==12072== Uninitialised value was created by a stack allocation
==12072== at 0x400500: main (in /home/smatz/gcc-bug/1256/a.out)
==12072==
$ g++-4_6-r197894 -O2 p4736b.ii
$ valgrind -q --track-origins=yes ./a.out
(no output)
The code seems valid and defined to me, but somebody else might know otherwise.
I haven't analysed whether messages output by valgrind for gcc 4.7 are valid or
just false positives.
Tested revisions:
trunk r210412 - SIGSEGV
4_9 r210307 - SIGSEGV
4_8 r210303 - SIGSEGV
4_7 r210302 - valgrind warnings, but no crash
4_6 r197894 - OK
