get wrecked clang

0_test.c

#include <stdlib.h>

int test() {
  int *x = NULL;
  int  y = rand();
  int  z = rand();
  int  v = 4;

  if (z == 8) x = &v;

  if (y != 4) __builtin_unreachable();
  if (y != 4) abort();

  if (!x) __builtin_unreachable();
  if (!x) abort();

  int p2 = __builtin_popcount(z) == 1;
  if (p2) exit(0);
  else    exit(1);
}

1_gcc.s

	.file	"test.c"
	.text
	.p2align 4
	.globl	test
	.type	test, @function
test:
.LFB11:
	.cfi_startproc
	subq	$8, %rsp
	.cfi_def_cfa_offset 16
	call	rand@PLT
	call	rand@PLT
	xorl	%edi, %edi
	call	exit@PLT
	.cfi_endproc
.LFE11:
	.size	test, .-test
	.ident	"GCC: (GNU) 9.2.0"
	.section	.note.GNU-stack,"",@progbits

2_clang.s

	.text
	.file	"test.c"
	.globl	test                    # -- Begin function test
	.p2align	4, 0x90
	.type	test,@function
test:                                   # @test
	.cfi_startproc
# %bb.0:
	pushq	%rbx
	.cfi_def_cfa_offset 16
	.cfi_offset %rbx, -16
	callq	rand@PLT
	movl	%eax, %ebx
	callq	rand@PLT
	cmpl	$4, %ebx
	jne	.LBB0_3
# %bb.1:
	cmpl	$8, %eax
	jne	.LBB0_3
# %bb.2:
	xorl	%edi, %edi
	callq	exit@PLT
.LBB0_3:
	callq	abort@PLT
.Lfunc_end0:
	.size	test, .Lfunc_end0-test
	.cfi_endproc
                                        # -- End function

	.ident	"clang version 8.0.1 (tags/RELEASE_801/final)"
	.section	".note.GNU-stack","",@progbits
	.addrsig

3_details

> gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --with-system-zlib --with-isl --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-gnu-indirect-function --enable-multilib --disable-werror --enable-checking=release --enable-default-pie --enable-default-ssp --enable-cet=auto
Thread model: posix
gcc version 9.2.0 (GCC) 


> clang -v
clang version 8.0.1 (tags/RELEASE_801/final)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-pc-linux-gnu/9.2.0
Found candidate GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/9.2.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0
Found candidate GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/9.2.0
Selected GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/9.2.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64


both compiled with ${CC} test.c -S -O3