https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104805
Bug ID: 104805
Summary: [12.0] x86_64 Extended asm may use rbp register to
input/output even thougth "rbp" is in the clobber list
when "rsp" and "rbp" are both in the in the clobber
list
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: 570070308 at qq dot com
Target Milestone: ---
test.c:
```
void kkk()
{
char a;
__asm__ volatile (
"%0"
:"+m"(a)
:
: "rsp","rbp"
);
}
```
assembly code:
```
#APP
# 4 "test.c" 1
-9(%rbp)
# 0 "" 2
#NO_APP
```
can see that it use `-9(%rbp)` to represent `a`. Accouding to
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Clobbers-and-Scratch-Registers,
the rbp should not be use to represent any operands because it is in the
clobber list.
compile log:
```
ig@ig-virtual-machine:~/temp$ gcc-12 -S test.c -O1 -v
Using built-in specs.
COLLECT_GCC=gcc-12
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
12-20220302-1ubuntu1' --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
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new
--enable-gnu-unique-object --disable-vtable-verify --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-12-VlTCdr/gcc-12-12-20220302/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-12-VlTCdr/gcc-12-12-20220302/debian/tmp-gcn/usr
--enable-offload-defaulted --without-cuda-driver --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.1 20220302 (experimental) [master r12-7448-g58394373a70]
(Ubuntu 12-20220302-1ubuntu1)
COLLECT_GCC_OPTIONS='-S' '-O1' '-v' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/12/cc1 -quiet -v -imultiarch x86_64-linux-gnu
test.c -quiet -dumpbase test.c -dumpbase-ext .c -mtune=generic -march=x86-64
-O1 -version -o test.s -fasynchronous-unwind-tables -fstack-protector-strong
-Wformat -Wformat-security -fstack-clash-protection -fcf-protection
GNU C17 (Ubuntu 12-20220302-1ubuntu1) version 12.0.1 20220302 (experimental)
[master r12-7448-g58394373a70] (x86_64-linux-gnu)
compiled by GNU C version 12.0.1 20220302 (experimental) [master
r12-7448-g58394373a70], GMP version 6.2.1, MPFR version 4.1.0, MPC version
1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/12/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-linux-gnu/12/include
/usr/local/include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C17 (Ubuntu 12-20220302-1ubuntu1) version 12.0.1 20220302 (experimental)
[master r12-7448-g58394373a70] (x86_64-linux-gnu)
compiled by GNU C version 12.0.1 20220302 (experimental) [master
r12-7448-g58394373a70], GMP version 6.2.1, MPFR version 4.1.0, MPC version
1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 3929bb57dd80f5cc2d4f3202c349e2dc
test.c: In function ‘kkk’:
test.c:4:5: warning: listing the stack pointer register ‘rsp’ in a clobber list
is deprecated [-Wdeprecated]
4 | __asm__ volatile (
| ^~~~~~~
test.c:4:5: note: the value of the stack pointer after an ‘asm’ statement must
be the same as it was before the statement
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/12/:/usr/lib/gcc/x86_64-linux-gnu/12/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/12/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/12/:/usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/12/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/12/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-S' '-O1' '-v' '-mtune=generic' '-march=x86-64'
ig@ig-virtual-machine:~/temp$
```
if compile with -O0, then gcc will give an error.
if don't put "rsp" and "rbp" both in the clobber list, the result will be
right.
gcc is installed by apt on ubuntu 22.04
