[MC,test] Add a stress test for layout algorithm

Reduced from #100283

Author: MaskRay

llvm/test/MC/ELF/layout-interdependency2.s

@@ -0,0 +1,84 @@
+## Contrived .zero directive example, simplified from the Linux kernel use case,
+## which requires multiple iterations to converge.
+## https://github.com/llvm/llvm-project/issues/100283
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t
+# RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
+
+# CHECK:       80: jne 0x0 <.text>
+# CHECK-EMPTY:
+
+	.text
+.Ltmp0:
+.Ltmp1:
+	cli
+	popq	%rdi
+text1:
+	.zero	(.Ltmp2-.Ltmp3)
+	.section	"","ax",@progbits
+.Ltmp3:
+	movq	$0, %rax
+.Ltmp4:
+.Ltmp5:
+	.section	.discard.intra_function_calls,"ax",@progbits
+	.long	.Ltmp5
+	.section	"","ax",@progbits
+	callq	.Ltmp6
+	int3
+.Ltmp7:
+.Ltmp8:
+	.section	.discard.intra_function_calls,"ax",@progbits
+	.long	.Ltmp8
+	.section	"","ax",@progbits
+	callq	.Ltmp6
+	int3
+.Ltmp6:
+	addq	$0, %rsp
+	decq	%rax
+	jne	.Ltmp4
+	lfence
+	movq	$-1, %gs:pcpu_hot+6
+
+.Ltmp2:
+	.text
+text2:
+
+	.zero	(.Ltmp9-.Ltmp10)
+	.section	"","ax",@progbits
+.Ltmp10:
+	jmp	.Ltmp11
+.Ltmp9:
+	.text
+text3:
+
+.Ltmp12:
+	.zero	(.Ltmp13-.Ltmp14)
+	.section	"","ax",@progbits
+.Ltmp14:
+	callq	entry_untrain_ret
+.Ltmp13:
+	.text
+
+	.zero	(.Ltmp15-.Ltmp16)
+	.section	"","ax",@progbits
+.Ltmp16:
+	xorl	%eax, %eax
+	btsq	$63, %rax
+	movq	%rax, %gs:pcpu_hot+6
+
+.Ltmp15:
+	.text
+
+	popq	%r12
+	popq	rbp
+	jmp	__x86_return_thunk
+	movl	936(%rdi), %eax
+	cmpl	%gs:x86_spec_ctrl_current, %eax
+	je	.Ltmp0
+	movl	edx, %edx
+	wrmsr
+	jmp	.Ltmp0
+.Ltmp11:
+	movl	$72, %ecx
+	jmp	.Ltmp12
+	cmpb	$0, kvm_rebooting
+	jne	.Ltmp1