The matrix-matrix-multiply from romz-pl

I use ryzen 4800h with no avx512 support, and try to change `n` in `check.cpp`, but weird failure.

After commenting all functions related with avx512, all work well,

But error thrown after adding the following modification (initially I use 4*4 then try 8*4,etc):

diff --git a/src/check.cpp b/src/check.cpp
index 5172492..93e5876 100644
--- a/src/check.cpp
+++ b/src/check.cpp
@@ -43,16 +43,19 @@ static double calc_abs_sum(const uint32_t n, const double* c, const double* q)
 void check()
 {
     constexpr uint32_t trial_no = 11;
-    constexpr uint32_t n = 32 * 4;
-    constexpr double eps = 1e-6;
+    /* why 32/16/8 *4 work , but 4*4 fails*/
+    // constexpr uint32_t n = 8 * 4;
+    constexpr uint32_t n = 4 * 4;
 
     std::vector< Dgemm > all_dgemm =
     {
         {dgemm_basic_blocked, "dgemm_basic_blocked"},
         {dgemm_avx256, "dgemm_avx256"},
-        {dgemm_avx512, "dgemm_avx512"},
-        {dgemm_unrolled, "dgemm_unrolled"},
-        {dgemm_blocked, "dgemm_blocked"},
+        //{dgemm_avx512, "dgemm_avx512"},
+        //{dgemm_unrolled, "dgemm_unrolled"},
+        //{dgemm_blocked, "dgemm_blocked"},
     };

and when running with n = 4 * 4; error thrown:

$ ~/matrix-matrix-multiply/build/src/dgemm
double free or corruption (!prev)
zsh: IOT instruction (core dumped)  ~/matrix-matrix-multiply/build/src/dgemm
$ coredumpctl debug
pwndbg> bt
#0  0x00007f9b22ea08ec in ?? () from /usr/lib/libc.so.6
#1  0x00007f9b22e51ea8 in raise () from /usr/lib/libc.so.6
#2  0x00007f9b22e3b53d in abort () from /usr/lib/libc.so.6
#3  0x00007f9b22e3c29e in ?? () from /usr/lib/libc.so.6
#4  0x00007f9b22eaa657 in ?? () from /usr/lib/libc.so.6
#5  0x00007f9b22eac7bc in ?? () from /usr/lib/libc.so.6
#6  0x00007f9b22eaee63 in free () from /usr/lib/libc.so.6
#7  0x000056328f5f9383 in check () at /home/czg/matrix-matrix-multiply/src/check.cpp:87
#8  0x000056328f5f8599 in main () at /home/czg/matrix-matrix-multiply/src/main.cpp:6
#9  0x00007f9b22e3c790 in ?? () from /usr/lib/libc.so.6
#10 0x00007f9b22e3c84a in __libc_start_main () from /usr/lib/libc.so.6
#11 0x000056328f5f85d5 in _start ()
pwndbg> up 7
   f 0   0x7f9b22ea08ec
   f 1   0x7f9b22e51ea8 raise+24
   f 2   0x7f9b22e3b53d abort+215
   f 3   0x7f9b22e3c29e
   f 4   0x7f9b22eaa657
   f 5   0x7f9b22eac7bc
   f 6   0x7f9b22eaee63 free+115
 ► f 7   0x56328f5f9383 check()+963
   f 8   0x56328f5f8599 main+9
   f 9   0x7f9b22e3c790
   f 10   0x7f9b22e3c84a __libc_start_main+138
   f 11   0x56328f5f85d5 _start+37
pwndbg> disassemble
...
   0x000056328f5f9378 <check()+952>:    48 89 ef                mov    rdi,rbp
   0x000056328f5f937b <check()+955>:    4c 89 f3                mov    rbx,r14
   0x000056328f5f937e <check()+958>:    e8 cd 05 00 00          call   0x56328f5f9950 <Mtx::~Mtx()>
=> 0x000056328f5f9383 <check()+963>:    4c 89 ff                mov    rdi,r15

I am not very familiar with cpp, not know why pass rbp to rdi as parameter to free will throw error.

after directly debugging with gdb, the program invoke two free with operator delete with str like "dgemm_basic_blocked" as the parameter, then I have checked the parameter to free which throw error, and found that the pointer is located in heap which should not throw error

$ gdb ~/matrix-matrix-multiply/build/src/dgemm -ex 'br free' -ex 'r' -ex 'c 2'
pwndbg> bt
#0  0x00007ffff7a65df0 in free () from /usr/lib/libc.so.6
#1  0x0000555555557383 in check () at /home/czg/matrix-matrix-multiply/src/check.cpp:87
#2  0x0000555555556599 in main () at /home/czg/matrix-matrix-multiply/src/main.cpp:6
pwndbg> up
pwndbg> disassemble
...
   0x0000555555557378 <check()+952>:    48 89 ef                mov    rdi,rbp
   0x000055555555737b <check()+955>:    4c 89 f3                mov    rbx,r14
   0x000055555555737e <check()+958>:    e8 cd 05 00 00          call   0x555555557950 <Mtx::~Mtx()>
=> 0x0000555555557383 <check()+963>:    4c 89 ff                mov    rdi,r15
pwndbg> disassemble 0x555555557950
Dump of assembler code for function Mtx::~Mtx():
   0x0000555555557950 <+0>:     mov    rdi,QWORD PTR [rdi]
   0x0000555555557953 <+3>:     jmp    0x555555556100 <free@plt>
pwndbg> x/g $rbp
0x7fffffffdea0: 0x000055555556e940
pwndbg> vmmap
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
             Start                End Perm     Size Offset File
    0x555555554000     0x555555556000 r--p     2000      0 /home/czg/matrix-matrix-multiply/build/src/dgemm
    0x555555556000     0x555555558000 r-xp     2000   2000 /home/czg/matrix-matrix-multiply/build/src/dgemm
    0x555555558000     0x555555559000 r--p     1000   4000 /home/czg/matrix-matrix-multiply/build/src/dgemm
    0x555555559000     0x55555555a000 r--p     1000   4000 /home/czg/matrix-matrix-multiply/build/src/dgemm
    0x55555555a000     0x55555555b000 rw-p     1000   5000 /home/czg/matrix-matrix-multiply/build/src/dgemm
    0x55555555b000     0x55555557c000 rw-p    21000      0 [heap]

as shown above [$rbp]=0x000055555556e940 which is between 0x55555555b000 and 0x55555557c000 (i.e. is in heap).

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I use ryzen 4800h with no avx512 support, and try to change `n` in `check.cpp`, but weird failure.

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