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From: "cesarb at nitnet dot com dot br" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug optimization/14907] New: bogus sign/zero extension when relaying parameters with regparm Date: Sat, 10 Apr 2004 14:59:00 -0000 [thread overview] Message-ID: <20040410140503.14907.cesarb@nitnet.com.br> (raw) (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
next reply other threads:[~2004-04-10 14:05 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-04-10 14:59 cesarb at nitnet dot com dot br [this message] 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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