https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113989
Bug ID: 113989
Summary: MinGW generates unaligned vmovdqa64
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: xjkp2283572185 at gmail dot com
Target Milestone: ---
===
Compiler
===
Using built-in specs.
COLLECT_GCC=D:\Tools\gcc\bin\g++.exe
COLLECT_LTO_WRAPPER=D:/Tools/gcc/bin/../libexec/gcc/x86_64-w64-mingw32/14.0.1/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../configure --disable-werror
--prefix=/home/luo/x86_64-w64-mingw32-native-gcc14 --host=x86_64-w64-mingw32
--target=x86_64-w64-mingw32 --enable-multilib --enable-languages=c,c++
--disable-sjlj-exceptions --enable-threads=win32
Thread model: win32
Supported LTO compression algorithms: zlib
gcc version 14.0.1 20240130 (experimental) (GCC)
===
Source Code
===
// a.cpp
struct alignas(64) a
{
char buf[64]{};
};
a f(long long i) noexcept;
int main()
{
f(1);
return 0;
}
// b.bpp
struct alignas(64) a
{
char buf[64]{};
};
a f(long long i) noexcept
{
using v[[gnu::vector_size(64)]] = long long;
v vi{i,i,i,i,i,i,i,i};
a res{};
__builtin_memcpy(&res, &vi, 64);
return res;
}
===
Command
===
g++ a.cpp b.cpp -march=znver4 -Ofast -g
===
Result
===
Run it with gdb and it crashes:
Thread 1 received signal SIGSEGV, Segmentation fault.
0x00007ff78ac01549 in f (i=i@entry=1) at b.cpp:10
10 __builtin_memcpy(&res, &vi, 64);
(gdb) disassemble
Dump of assembler code for function _Z1fx:
0x00007ff78ac01540 <+0>: vpbroadcastq %rdx,%zmm0
0x00007ff78ac01546 <+6>: mov %rcx,%rax
=> 0x00007ff78ac01549 <+9>: vmovdqa64 %zmm0,(%rcx)
0x00007ff78ac0154f <+15>: vzeroupper
0x00007ff78ac01552 <+18>: ret
End of assembler dump.
(gdb) info registers rcx
rcx 0x5ffe90 6291088
(gdb) disassemble main
Dump of assembler code for function main():
0x00007ff640f62a50 <+0>: sub $0x68,%rsp
0x00007ff640f62a54 <+4>: call 0x7ff640f61610 <__main>
0x00007ff640f62a59 <+9>: lea 0x20(%rsp),%rcx
0x00007ff640f62a5e <+14>: mov $0x1,%edx
0x00007ff640f62a63 <+19>: call 0x7ff640f61540 <_Z1fx>
0x00007ff640f62a68 <+24>: xor %eax,%eax
0x00007ff640f62a6a <+26>: add $0x68,%rsp
0x00007ff640f62a6e <+30>: ret
End of assembler dump.
But if we compile the program with "g++ a.cpp b.cpp -march=znver4 -Ofast
-fno-asynchronous-unwind-tables -fno-exceptions", the program won't crash.
