# Pin: W65816StackSlotCleanup's temp-slot forwarding (Pass 2.4) and its
# never-read store sweep (Pass 2.5).
#
# The far-pointer staging inserters move a pointer word to $E0 / $E2 through
# a fresh stack object: `STAfi src, T ; ... ; LDAfi T ; STA_DP $E2`.  With the
# word in an IMG register and A live, the store alone cost
# `pha ; lda dp ; sta n,s ; pla`.  The reload now reads the IMG word itself
# (LDAimg, `lda dp` after expansion) and the store, read by nothing any more,
# goes; so do stores to objects nothing ever read (consecutive-deref CSE left
# those behind: CoreMark's list reversal paid two pairs per node).
#
# forward:        IMG word unchanged between store and reload: forwarded,
#                 store dropped.
# img_redefined:  the IMG register is written in between: both stay.
# dp_touched:     a direct-page access to the IMG word in between: both stay.
# two_reads:      the slot is read twice: both stay.
# never_read:     a store to an object nothing reads: dropped.
# addr_taken:     an ADDframe of the object counts as a read: kept.
#
# RUN: llc -mtriple=w65816 -run-pass=w65816-stack-slot-cleanup -o - %s | FileCheck %s
--- |
  target triple = "w65816"
  define void @forward() { ret void }
  define void @img_redefined() { ret void }
  define void @dp_touched() { ret void }
  define void @two_reads() { ret void }
  define void @never_read() { ret void }
  define void @addr_taken() { ret void }
...
---
# CHECK-LABEL: name: forward
# CHECK:       $img0 = COPY $x
# CHECK-NOT:   STAfi
# CHECK-NOT:   LDAfi
# CHECK:       $a = LDAimg $img0
# CHECK-NEXT:  STA_DP 226
name: forward
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $img0 = COPY $x
    STAfi $img0, %stack.0, 0, implicit-def dead $a
    $a = LDAi16imm 7
    STA_DP 224, implicit $a
    dead $a = LDAfi %stack.0, 0
    STA_DP 226
    RTL
...
---
# CHECK-LABEL: name: img_redefined
# CHECK:       STAfi $img0, %stack.0, 0
# CHECK:       $a = LDAfi %stack.0, 0
name: img_redefined
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $img0 = COPY $x
    STAfi $img0, %stack.0, 0, implicit-def dead $a
    $img0 = COPY $y
    $a = LDAfi %stack.0, 0
    STA_DP 226, implicit $a
    RTL
...
---
# CHECK-LABEL: name: dp_touched
# CHECK:       STAfi $img1, %stack.0, 0
# CHECK:       $a = LDAfi %stack.0, 0
name: dp_touched
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $img1 = COPY $x
    STAfi $img1, %stack.0, 0, implicit-def dead $a
    INC_DP 210
    $a = LDAfi %stack.0, 0
    STA_DP 226, implicit $a
    RTL
...
---
# CHECK-LABEL: name: two_reads
# CHECK:       STAfi $img0, %stack.0, 0
# CHECK:       $a = LDAfi %stack.0, 0
# CHECK:       $a = LDAfi %stack.0, 0
name: two_reads
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $img0 = COPY $x
    STAfi $img0, %stack.0, 0, implicit-def dead $a
    $a = LDAfi %stack.0, 0
    STA_DP 224, implicit $a
    $a = LDAi16imm 1
    STA_DP 228, implicit $a
    $a = LDAfi %stack.0, 0
    STA_DP 226, implicit $a
    RTL
...
---
# CHECK-LABEL: name: never_read
# CHECK:       $a = LDAi16imm 5
# CHECK-NOT:   STAfi
# CHECK:       RTL
name: never_read
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $a = LDAi16imm 5
    STAfi $a, %stack.0, 0, implicit-def $a
    RTL
...
---
# CHECK-LABEL: name: addr_taken
# CHECK:       STAfi $a, %stack.0, 0
# CHECK:       $a = ADDframe %stack.0, 0
name: addr_taken
tracksRegLiveness: false
stack:
  - { id: 0, size: 2, alignment: 1 }
body: |
  bb.0:
    $a = LDAi16imm 5
    STAfi $a, %stack.0, 0, implicit-def $a
    $a = ADDframe %stack.0, 0
    RTL
...