public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug target/109317] New: -Os generates bigger code than -O2 on 32-bit ARM
@ 2023-03-28 16:27 pali at kernel dot org
2023-03-29 7:04 ` [Bug target/109317] " rguenth at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: pali at kernel dot org @ 2023-03-28 16:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109317
Bug ID: 109317
Summary: -Os generates bigger code than -O2 on 32-bit ARM
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: pali at kernel dot org
Target Milestone: ---
Target: arm-linux-gnueabi
Simple loops like the one in the example below are better optimized for size on
32-bit ARM with -O2 option than -Os option.
$ cat test-arm.c
char *test1(char *ptr) {
while (*ptr != '\0' || *(ptr+1) != '\0') ptr++;
ptr++;
return ptr;
}
$ arm-linux-gnueabi-gcc -O2 -c test-arm.c && arm-linux-gnueabi-objdump -d
test-arm.o
test-arm.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <test1>:
0: e5d02000 ldrb r2, [r0]
4: e2800001 add r0, r0, #1
8: e3520000 cmp r2, #0
c: 1afffffb bne 0 <test1>
10: e5d02000 ldrb r2, [r0]
14: e3520000 cmp r2, #0
18: 1afffff8 bne 0 <test1>
1c: e12fff1e bx lr
$ arm-linux-gnueabi-gcc -Os -c test-arm.c && arm-linux-gnueabi-objdump -d
test-arm.o
test-arm.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <test1>:
0: e1a03000 mov r3, r0
4: e5d32000 ldrb r2, [r3]
8: e2800001 add r0, r0, #1
c: e3520000 cmp r2, #0
10: 1afffffa bne 0 <test1>
14: e5d02000 ldrb r2, [r0]
18: e3520000 cmp r2, #0
1c: 1afffff7 bne 0 <test1>
20: e12fff1e bx lr
$ arm-linux-gnueabi-gcc -v
Using built-in specs.
COLLECT_GCC=arm-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/arm-linux-gnueabi/12/lto-wrapper
Target: arm-linux-gnueabi
Configured with: ../src/configure -v --with-pkgversion='Debian 12.2.0-14'
--with-bugurl=file:///usr/share/doc/gcc-12/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-12 --enable-shared
--enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/
--enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libitm
--disable-libquadmath --disable-libquadmath-support --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--without-target-system-zlib --enable-multiarch --disable-sjlj-exceptions
--with-arch=armv5te --with-float=soft --disable-werror
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=arm-linux-gnueabi --program-prefix=arm-linux-gnueabi-
--includedir=/usr/arm-linux-gnueabi/include
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.0 (Debian 12.2.0-14)
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-03-13 21:47 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-28 16:27 [Bug target/109317] New: -Os generates bigger code than -O2 on 32-bit ARM pali at kernel dot org
2023-03-29 7:04 ` [Bug target/109317] " rguenth at gcc dot gnu.org
2023-04-22 20:57 ` pali at kernel dot org
2024-03-13 21:47 ` pali at kernel dot org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).