# Pin: W65816StackSlotCleanup Pass 1c drops `CMPi16imm $a, 0` after an op
# that already set N/Z from A, but only when the branch it feeds reads N or
# Z.  `cmp #0` also sets C (always 1), so before a BCC/BCS the CMP is the
# carry's only source and has to stay.
#
# The pre-2026-09-28 i32 compare lowering emitted exactly this shape for the
# high half of an unsigned compare against a 16-bit constant (`hi <u 0`,
# i.e. `lda hi ; cmp #0 ; bcc`).  With the CMP erased the BCC tested a stale
# carry, and `x >= 0x8000`, `x > 1`, `x < 0xFFFF` ... on a uint32_t took
# the wrong branch whenever x had a non-zero high half.
#
# keep_bcc:  CMP #0 before BCC stays.
# keep_bcs:  CMP #0 before BCS stays.
# drop_beq:  CMP #0 before BEQ still goes (the LDA's Z is the same).
#
# RUN: llc -mtriple=w65816 -run-pass=w65816-stack-slot-cleanup -o - %s | FileCheck %s
--- |
  target triple = "w65816"
  define void @keep_bcc() { ret void }
  define void @keep_bcs() { ret void }
  define void @drop_beq() { ret void }
...
---
# CHECK-LABEL: name: keep_bcc
# CHECK:      $a = LDAfi %stack.0, 0
# CHECK-NEXT: CMPi16imm killed $a, 0, implicit-def $p
# CHECK-NEXT: BCC %bb.1, implicit $p
name: keep_bcc
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    successors: %bb.1, %bb.2
    $a = LDAfi %stack.0, 0
    CMPi16imm killed $a, 0, implicit-def $p
    BCC %bb.1, implicit $p
    BRA %bb.2
  bb.1:
    RTL
  bb.2:
    RTL
...
---
# CHECK-LABEL: name: keep_bcs
# CHECK:      $a = LDAfi %stack.0, 0
# CHECK-NEXT: CMPi16imm killed $a, 0, implicit-def $p
# CHECK-NEXT: BCS %bb.1, implicit $p
name: keep_bcs
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    successors: %bb.1, %bb.2
    $a = LDAfi %stack.0, 0
    CMPi16imm killed $a, 0, implicit-def $p
    BCS %bb.1, implicit $p
    BRA %bb.2
  bb.1:
    RTL
  bb.2:
    RTL
...
---
# CHECK-LABEL: name: drop_beq
# CHECK:      $a = LDAfi %stack.0, 0
# CHECK-NOT:  CMPi16imm
# CHECK:      BEQ %bb.1, implicit $p
name: drop_beq
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    successors: %bb.1, %bb.2
    $a = LDAfi %stack.0, 0
    CMPi16imm killed $a, 0, implicit-def $p
    BEQ %bb.1, implicit $p
    BRA %bb.2
  bb.1:
    RTL
  bb.2:
    RTL
...