[BOLT] Ensure remember and restore CFIs are in the same list

bolt/include/bolt/Core/BinaryFunction.h

@@ -1663,7 +1663,11 @@ class BinaryFunction {
       Offset = I->first;
     }
     assert(I->first == Offset && "CFI pointing to unknown instruction");
-    if (I == Instructions.begin()) {
+    // When dealing with RememberState, we place this CFI in FrameInstructions.
+    // We want to ensure RememberState and RestoreState CFIs are in the same
+    // list in order to properly populate the StateStack.
+    if (I == Instructions.begin() &&
+        Inst.getOperation() != MCCFIInstruction::OpRememberState) {
       CIEFrameInstructions.emplace_back(std::forward<MCCFIInstruction>(Inst));
       return;
     }

bolt/test/AArch64/cfi-state-list.test

@@ -0,0 +1,34 @@
+// This test checks that BOLT does not split remember and restore CFI states
+// into different lists, which would cause an assertion failure.
+
+# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
+# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt 2>&1 | FileCheck %s
+
+# CHECK: BOLT-INFO: Starting stub-insertion pass
+
+.text
+.global main
+.type main, %function
+
+main:
+.cfi_startproc
+.cfi_remember_state
+  mov	w0, wzr
+  b.ne .L1
+.L0:
+  mov	w0, wzr
+.L1:
+  cmp	x0, #0
+  b.lt .L2
+.L2:
+  nop
+  .cfi_restore_state
+  mov	x8, xzr
+  b.ls .L0
+  ret
+.cfi_endproc
+    .size main, .-main
+
+## Force relocation mode.
+  .reloc 0, R_AARCH64_NONE