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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; 5+ 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] 5+ messages in thread
[parent not found: <bug-14907-1037@http.gcc.gnu.org/bugzilla/>]
* [Bug target/14907] bogus sign/zero extension when relaying parameters with regparm
[not found] <bug-14907-1037@http.gcc.gnu.org/bugzilla/>
@ 2006-03-01 5:54 ` nmiell at comcast dot net
0 siblings, 0 replies; 5+ messages in thread
From: nmiell at comcast dot net @ 2006-03-01 5:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from nmiell at comcast dot net 2006-03-01 05:54 -------
This also occurs on AMD64 without any special attributes (the ABI passes params
in registers already).
When compiling:
extern char c2(char);
char c1(char c) { return c2(c); }
with gcc -Wall -O2 -S tail-char.c
using gcc (GCC) 4.0.2 20051125 (Red Hat 4.0.2-8)
The result is:
c1:
subq $8, %rsp
movsbl %dil,%edi
call c2
addq $8, %rsp
movsbl %al,%eax
ret
--
nmiell at comcast dot net changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |nmiell at comcast dot net
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14907
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2006-03-01 5:54 UTC | newest]
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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
[not found] <bug-14907-1037@http.gcc.gnu.org/bugzilla/>
2006-03-01 5:54 ` nmiell at comcast dot net
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