Is there an x86 instruction to create a core dump?

General question that I would like answered

I have some x86 assembly code that I'm trying to debug. I'd like to get a core dump so I can inspect what is going on. Is there an x86 instruction (or set of instructions) that will generate a core dump at a given point in a program? Is there a way to assemble the assembly to make it core dump if there is an error?

Specific issue (explained here for context)

I am writing a compiler for a small lambda calculus following An Incremental Approach to Compiler Construction. I'm working now on implementing closures, and I need to issue an indirect jump. I'm trying to compile this code:

(labels ((f (code (n) () (+ n 1)))) (app (closure f) 3))

My compiler generates the following:

     .text     .p2align 4,,15     .globl _scheme_entry _scheme_entry:     movq %rdi, %r15     jmp _definition_end38349 _func_f38350:     movq $4, %rax     movq %rax, -16(%rsp)     movq -8(%rsp), %rax     addq -16(%rsp), %rax     ret _definition_end38349:     movq $12, %rax     movq %rax, -24(%rsp)     movq %rdi, -8(%rsp)     leaq _func_f38350(%rip), %rax     movq %rax, 0(%r15)     movq %r15, %rax     orq $6, %rax     addq $8, %r15     xorq $6, %rax     movq %rax, %rdi     addq $8, %rsp     callq *%rdi     subq $8, %rsp     movq -8(%rsp), %rdi     ret

I have an accompanying driver file written in C that handles the formatting and display of the result of the compiled code. For reference, here it is:

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #define fixnum_mask  3 #define fixnum_tag   0 #define fixnum_shift 2 #define data_mask    7 #define cons_tag     1 #define vector_tag   2 #define string_tag   3 #define symb_tag     5 #define closure_tag  6 #define empty_list   47 #define char_tag     15 #define char_mask    255 #define char_shift   8 #define bool_tag     31 #define bool_mask    127 #define bool_shift   7 #define heap_size    8192 size_t scheme_entry(size_t *heap); void format_val(size_t val); int main(int argc, char** argv) {   size_t *heap = malloc(heap_size);   size_t val = scheme_entry(heap);   format_val(val);   return 0; } void format_val(size_t val) {   if ((val & bool_mask) == bool_tag) {     printf((val >> bool_shift) ? "#t" : "#f");   }   else if ((val & fixnum_mask) == fixnum_tag) {     printf("%zu", val >> fixnum_shift);   }   else if ((val & data_mask) == closure_tag) {     printf("#<closure %zx>", val);   }   else if ((val & fixnum_mask) == cons_tag) {     val--;     size_t car = *((size_t*)val);     size_t cdr = *((size_t*)val + 1);     printf("("); format_val(car); printf(" . "); format_val(cdr); printf(")");   }   else if (val == empty_list) {     printf("()");   }   /* else if ((val & char_mask) == char_tag) { */   /*   printf("%c", val >> char_shift); */   /* } */   else {     printf("#<unknown value: %zx>", val);   } }

It compiles without complaint on macOS when I run gcc assembly-file.s driver.c. When I run the resulting a.out file, I get the following error:

[2]    84530 bus error  ./a.out

Is there a way I can get a core dump so I can inspect the values of the registers?

Bonus: if you can see what's wrong with my assembly, I wouldn't mind an answer to that either. ;-) I've tried using the GDB with my code, but it freezes every time I try it out on the a.out file.

I'm running this on macOS; gcc --version gives:

Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1Apple clang version 11.0.3 (clang-1103.0.32.62)Target: x86_64-apple-darwin19.4.0Thread model: posixInstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

Much appreciated.