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* [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm @ 2004-04-10 14:59 cesarb at nitnet dot com dot br 2004-04-10 15:48 ` [Bug target/14907] " pinskia at gcc dot gnu dot org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: cesarb at nitnet dot com dot br @ 2004-04-10 14:59 UTC (permalink / raw) To: gcc-bugs (this seem to be another case of the general bug of "the compiler doesn't know when it has already extended the value") This is the "other side" of PR 14903 When compiling: extern void __attribute__((__regparm__(3))) f(unsigned char x); void __attribute__((__regparm__(3))) g(unsigned char x) { f(x); } With: gcc -W -Wall -Os -fomit-frame-pointer -save-temps -c The result is: g: movzbl %al, %eax jmp f Notice again the bogus zero extension (sign extension with signed char). The same happens with shorts. While PR 14903 can cause excessive stack usage, this one just looks dumb in the assembly output. Reading specs from /usr/lib/gcc-lib/i486-linux/3.3.3/specs Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/c++/3.3 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --enable-__cxa_atexit --enable-clocale=gnu --enable-debug --enable-java-gc=boehm --enable-java-awt=xlib --enable-objc-gc i486-linux Thread model: posix gcc version 3.3.3 (Debian 20040401) -- Summary: bogus sign/zero extension when relaying parameters with regparm Product: gcc Version: 3.3.3 Status: UNCONFIRMED Severity: normal Priority: P2 Component: optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: cesarb at nitnet dot com dot br CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: i686-pc-linux-gnu GCC host triplet: i686-pc-linux-gnu GCC target triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14907 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/14907] bogus sign/zero extension when relaying parameters with regparm 2004-04-10 14:59 [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm cesarb at nitnet dot com dot br @ 2004-04-10 15:48 ` pinskia at gcc dot gnu dot org 2004-04-10 18:13 ` [Bug optimization/14907] " cesarb at nitnet dot com dot br 2004-07-10 1:28 ` [Bug target/14907] " pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-04-10 15:48 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2004-04-10 15:31 ------- Confirmed. I think this is requied by the ABI to promote it but since it is already promoted it could just use the full register, I do not know if this is really a bug but then again I could be wrong. -- What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Component|optimization |target Ever Confirmed| |1 Keywords| |pessimizes-code Last reconfirmed|0000-00-00 00:00:00 |2004-04-10 15:31:46 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14907 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug optimization/14907] bogus sign/zero extension when relaying parameters with regparm 2004-04-10 14:59 [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm cesarb at nitnet dot com dot br 2004-04-10 15:48 ` [Bug target/14907] " pinskia at gcc dot gnu dot org @ 2004-04-10 18:13 ` cesarb at nitnet dot com dot br 2004-07-10 1:28 ` [Bug target/14907] " pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: cesarb at nitnet dot com dot br @ 2004-04-10 18:13 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From cesarb at nitnet dot com dot br 2004-04-10 15:56 ------- regparm is a different (gcc-specific) version of the ABI right? (But someone should check if the bogus extensions happen when loading the arguments from the stack too, and check if they are really bogus when reading from the stack). -- What |Removed |Added ---------------------------------------------------------------------------- Component|target |optimization http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14907 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/14907] bogus sign/zero extension when relaying parameters with regparm 2004-04-10 14:59 [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm cesarb at nitnet dot com dot br 2004-04-10 15:48 ` [Bug target/14907] " pinskia at gcc dot gnu dot org 2004-04-10 18:13 ` [Bug optimization/14907] " cesarb at nitnet dot com dot br @ 2004-07-10 1:28 ` pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-07-10 1:28 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2004-07-10 01:28 ------- Basically the problem is that the RTL optimizers do not know if they come in as full 32bit register even though the ABI demands it. -- What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed|2004-04-10 15:31:46 |2004-07-10 01:28:55 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14907 ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2004-07-10 1:28 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2004-04-10 14:59 [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm cesarb at nitnet dot com dot br 2004-04-10 15:48 ` [Bug target/14907] " pinskia at gcc dot gnu dot org 2004-04-10 18:13 ` [Bug optimization/14907] " cesarb at nitnet dot com dot br 2004-07-10 1:28 ` [Bug target/14907] " pinskia at gcc dot gnu dot org
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