[Bug target/126382] [16/17 regression] Incorrect compiler generated code resulting in seg fault - hoisted tls() in x86_cse caused register clobbering

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126382

--- Comment #2 from Reshma Roy <Reshma.Roy at amd dot com> ---
(In reply to H.J. Lu from comment #1)
> (In reply to Reshma Roy from comment #0)
> > Created attachment 65120 [details]
> > The preprocessed input file to be used for the command mentioned in the
> > description
> > 
> > GCC version: gcc (GCC) 17.0.0 20260722 (experimental)
> > 
> > GCC trunk generates incorrect code for AVX stack-realigned functions. This
> > causes a null pointer to dereference in libFLAME's legacy test suite
> > during Hessenberg reduction (FLA_Obj_datatype_check.c:18).
> > 
> > Bisection points to 5cf1b9a03ec5b617af8c50c1e9c0d223083fd7f2 ("x86-64:
> > Remove redundant TLS calls").
> > 
> > -----------------------------------------------------------------------------
> > --
> > Reduced test case:
> > 
> > typedef struct { long n; long m_inner; long n_inner; int base; } FLA_Obj;
> > __thread FLA_Obj FLA_ONE, W12;
> > long FLA_Obj_length ();
> > void FLA_Obj_width ();
> > void f (FLA_Obj A)
> > {
> >   while (FLA_Obj_length (A))
> >     FLA_Obj_width (FLA_ONE);
> >   FLA_Obj_width (FLA_ONE, W12);
> > }
> > 
> > Reproducer: gcc -mtune=native -O3 -mavx512f -mavx512dq -mfma
> > -fstack-protector-strong -fpie -std=c11 -fPIC -S -o testcase.s testcase.i
> > 
> 
> Please show the output of
> 
> $ gcc -v -mtune=native -O3 -mavx512f -mavx512dq -mfma
> -fstack-protector-strong -fpie -std=c11 -fPIC -S -o testcase.s testcase.i

Output: 

Using built-in specs.
COLLECT_GCC=gcc
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --enable-languages=c,c++,fortran
--disable-bootstrap --disable-multilib --prefix=~/GCC/install : (reconfigured)
../gcc/configure --disable-bootstrap --disable-multilib
--prefix=/home/amd/reshma/GCC/install --enable-languages=c,c++,fortran,lto
--no-create --no-recursion
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 17.0.0 20260722 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-mtune=native' '-O3' '-mavx512f' '-mavx512dq' '-mfma'
'-fstack-protector-strong' '-std=c11' '-fPIC' '-S' '-o' 'testcase.s'
'-march=x86-64'
 ~/GCC/install/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/cc1 -fpreprocessed
repro-standalone-min-bad-fix-new.i --param l1-cache-size=48 --param
l1-cache-line-size=64 --param l2-cache-size=1024 -mtune=znver5 -quiet -dumpbase
testcase.i -dumpbase-ext .i -mavx512f -mavx512dq -mfma -march=x86-64 -O3
-std=c11 -version -fstack-protector-strong -fPIC -o testcase.s
GNU C11 (GCC) version 17.0.0 20260722 (experimental) (x86_64-pc-linux-gnu)
        compiled by GNU C version 13.3.0, GMP version 6.3.0, MPFR version
4.2.2, MPC version 1.3.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: 635c8853492582f21a9f9857f7e4e59d
COMPILER_PATH=~/GCC/install/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/:~/GCC/install/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/:~/GCC/install/libexec/gcc/x86_64-pc-linux-gnu/:~/GCC/install/lib/gcc/x86_64-pc-linux-gnu/17.0.0/:~/GCC/install/lib/gcc/x86_64-pc-linux-gnu/
LIBRARY_PATH=~/GCC/install/lib/../lib64/:/home/amd/reshma/GCC/install/lib64/../lib64/:~/GCC/install/lib/gcc/x86_64-pc-linux-gnu/17.0.0/:~/GCC/install/lib/gcc/x86_64-pc-linux-gnu/17.0.0/../../../../lib64/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib64/:~/GCC/install/lib/:/home/amd/reshma/GCC/install/lib64/:./:~/GCC/install/lib/gcc/x86_64-pc-linux-gnu/17.0.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-mtune=native' '-O3' '-mavx512f' '-mavx512dq' '-mfma'
'-fstack-protector-strong' '-std=c11' '-fPIC' '-S' '-o' 'testcase.s'
'-march=x86-64' '-dumpdir' 'testcase.'