# Regression test for the W65816StackSlotCleanup flag-preservation wrap
# (caeb78e follow-up: course_floor_piece hang / "reads uninitialized memory").
#
# RUN (see scripts/smokeTest.sh):
#   llc -march=w65816 -run-pass=w65816-stack-slot-cleanup flagWrapLoopGuard.mir
#
# This is the exact miscompiling shape: a loop-guard test `CMPi16imm $a, 0'
# (e.g. `mi < c->nmovers` with nmovers==0) whose branch reads $p, with a
# loop-invariant signed-compare bias `LDAfi contactY; EORi16imm #0x8000'
# scheduled BETWEEN the CMP and the branch.  LDA/EOR set N/Z on hardware but
# are NOT modeled with Defs=[P], so they physically trample the CMP's Z.  The
# StackSlotCleanup pass must bracket both in PHP/PLP so BEQ still sees the CMP's
# flags.  Before the fix its corruptor set (isLdaLike) omitted EORi16imm, so it
# stopped the backward walk AT the EOR (misclassifying it as the "test"), found
# no corruptor between it and BEQ, and inserted NO wrap -- the guard branched on
# (contactY^0x8000)==0 instead of nmovers==0, entered the zero-trip loop, and
# spun ~65536 iterations reading out of bounds.
#
# EXPECTED after the fix: a PHP is inserted before the LDAfi and a PLP after the
# EORi16imm (the smoke check greps for `PHP` between the CMP and the BEQ).
# Without the fix there is no PHP/PLP at all.
--- |
  target datalayout = "e-m:e-p:32:16-i16:16-i32:16-i64:16-f32:16-f64:16-a:8-n8:16-S8"
  target triple = "w65816"
  define void @flagWrapLoopGuard() { ret void }
...
---
name:            flagWrapLoopGuard
alignment:       1
tracksRegLiveness: true
frameInfo:
  maxAlignment:    2
  adjustsStack:    true
fixedStack:
  - { id: 0, type: default, offset: 4, size: 2, alignment: 1, isImmutable: true }
stack:
  - { id: 0, name: '', type: spill-slot, offset: 0, size: 2, alignment: 2 }
body:             |
  bb.0:
    successors: %bb.1(0x40000000), %bb.2(0x40000000)
    liveins: $a
    ; loop-guard test: nmovers == 0 (the value the BEQ must actually branch on)
    CMPi16imm $a, 0, implicit-def $p
    ; loop-invariant signed-compare bias scheduled into the guard gap; these
    ; physically set N/Z but are not modeled Defs=[P] -> must be PHP/PLP-wrapped
    $a = LDAfi %fixed-stack.0, 0
    $a = EORi16imm killed $a, -32768
    STAfi killed $a, %stack.0, 0, implicit-def $a
    BEQ %bb.2, implicit $p
    BRA %bb.1

  bb.1:
    RTS

  bb.2:
    RTS
...