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* [Bug driver/21795] New: reordering/aliasing effect on ppc64 @ 2005-05-28 7:50 hvr at gnu dot org 2005-05-28 7:55 ` [Bug driver/21795] " hvr at gnu dot org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: hvr at gnu dot org @ 2005-05-28 7:50 UTC (permalink / raw) To: gcc-bugs when compiling the attached gcc4bug.c with $ gcc -Wall -O2 -fno-strict-aliasing gcc4bug.c -o gcc4bug;./gcc4bug ;echo $? 39 the assertion in line 39 gets triggered on ppc64, even though -fno-strict-aliasing is used; looking at the assembler output, the 2 single-byte stores (together with the assertion-checks before the call to _hexdump() that got optimized away...) have been moved before the memcpy() /* setting memory... */ #NO_APP li 0,-54 ld 9,.LC3@toc(2) stb 0,120(1) // m_b li 0,-2 nop lhz 11,8(9) lwz 10,0(9) lwz 8,4(9) stb 0,121(1) // m_c sth 11,120(1) stw 10,112(1) stw 8,116(1) #APP /* done setting memory... */ interestingly, when enabling some of the commented out assert's in the .c file, the code gets reordered to produce the expected result (i.e. all assertions to hold, and the program to exit with a return code of 0) (this behaviour wasn't present in gcc-3.4 yet) $ gcc -v Using built-in specs. Target: powerpc64-linux Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --libexecdir=/usr/lib --enable-shared --with-system-zlib --enable-nls --enable-threads=posix --without-included-gettext --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --enable-mpfr --disable-nof --disable-softfloat --disable-werror --enable-checking=release powerpc64-linux Thread model: posix gcc version 4.0.1 20050503 (prerelease) (Debian 4.0.0-2) -- Summary: reordering/aliasing effect on ppc64 Product: gcc Version: 4.0.0 Status: UNCONFIRMED Severity: normal Priority: P2 Component: driver AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: hvr at gnu dot org CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: powerpc64-linux GCC host triplet: powerpc64-linux GCC target triplet: powerpc64-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21795 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug driver/21795] reordering/aliasing effect on ppc64 2005-05-28 7:50 [Bug driver/21795] New: reordering/aliasing effect on ppc64 hvr at gnu dot org @ 2005-05-28 7:55 ` hvr at gnu dot org 2005-05-28 9:54 ` [Bug middle-end/21795] " pinskia at gcc dot gnu dot org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: hvr at gnu dot org @ 2005-05-28 7:55 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From hvr at gnu dot org 2005-05-28 07:50 ------- Created an attachment (id=8983) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8983&action=view) C file triggering the issue -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21795 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/21795] reordering/aliasing effect on ppc64 2005-05-28 7:50 [Bug driver/21795] New: reordering/aliasing effect on ppc64 hvr at gnu dot org 2005-05-28 7:55 ` [Bug driver/21795] " hvr at gnu dot org @ 2005-05-28 9:54 ` pinskia at gcc dot gnu dot org 2005-05-28 14:39 ` [Bug rtl-optimization/21795] " pinskia at gcc dot gnu dot org 2005-07-01 19:36 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-05-28 9:54 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-05-28 08:08 ------- Note there is no C alias rules violating in the code as you can access anything via chars. -- What |Removed |Added ---------------------------------------------------------------------------- Component|driver |middle-end Keywords| |wrong-code http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21795 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/21795] reordering/aliasing effect on ppc64 2005-05-28 7:50 [Bug driver/21795] New: reordering/aliasing effect on ppc64 hvr at gnu dot org 2005-05-28 7:55 ` [Bug driver/21795] " hvr at gnu dot org 2005-05-28 9:54 ` [Bug middle-end/21795] " pinskia at gcc dot gnu dot org @ 2005-05-28 14:39 ` pinskia at gcc dot gnu dot org 2005-07-01 19:36 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-05-28 14:39 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-05-28 14:01 ------- Note, you are violating not aliasing rules but rule of going over the bounds of the array which is undefined by the C standard. -- What |Removed |Added ---------------------------------------------------------------------------- Component|middle-end |rtl-optimization http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21795 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/21795] reordering/aliasing effect on ppc64 2005-05-28 7:50 [Bug driver/21795] New: reordering/aliasing effect on ppc64 hvr at gnu dot org ` (2 preceding siblings ...) 2005-05-28 14:39 ` [Bug rtl-optimization/21795] " pinskia at gcc dot gnu dot org @ 2005-07-01 19:36 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-07-01 19:36 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-07-01 19:36 ------- This is still invalid as you are going passed the bounds which is undefined. -- What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21795 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2005-07-01 19:36 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2005-05-28 7:50 [Bug driver/21795] New: reordering/aliasing effect on ppc64 hvr at gnu dot org 2005-05-28 7:55 ` [Bug driver/21795] " hvr at gnu dot org 2005-05-28 9:54 ` [Bug middle-end/21795] " pinskia at gcc dot gnu dot org 2005-05-28 14:39 ` [Bug rtl-optimization/21795] " pinskia at gcc dot gnu dot org 2005-07-01 19:36 ` pinskia at gcc dot gnu dot org
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