[X86][NFC] Pre-commit test to show prolog insert problem

Author: phoebewang

llvm/test/CodeGen/X86/vaargs-prolog-insert.ll

@@ -0,0 +1,45 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64 < %s | FileCheck %s
+
+; Check the prolog won't be sunk across the save of CSRs.
+define void @reduce(i32, i32, i32, i32, i32, i32, ...) nounwind {
+; CHECK-LABEL: reduce:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    je .LBB0_4
+; CHECK-NEXT:  # %bb.3:
+; CHECK-NEXT:    movaps %xmm0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm1, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm2, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm3, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm4, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm5, (%rsp)
+; CHECK-NEXT:    movaps %xmm6, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movaps %xmm7, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:  .LBB0_4:
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    jne .LBB0_2
+; CHECK-NEXT:  # %bb.1:
+; CHECK-NEXT:    subq $56, %rsp
+; CHECK-NEXT:    leaq -{{[0-9]+}}(%rsp), %rax
+; CHECK-NEXT:    movq %rax, 16
+; CHECK-NEXT:    leaq {{[0-9]+}}(%rsp), %rax
+; CHECK-NEXT:    movq %rax, 8
+; CHECK-NEXT:    movl $48, 4
+; CHECK-NEXT:    movl $48, 0
+; CHECK-NEXT:    addq $56, %rsp
+; CHECK-NEXT:  .LBB0_2:
+; CHECK-NEXT:    retq
+  br i1 undef, label %8, label %7
+
+7:                                                ; preds = %6
+  call void @llvm.va_start(i8* null)
+  br label %8
+
+8:                                                ; preds = %7, %6
+  ret void
+}
+
+declare void @llvm.va_start(i8*)
+declare void @llvm.va_end(i8*)