CONTROL FLOW GRAPH SSA

void main()
main: scope:[main]  from __start
  first::msg#0 = msg1
  call first 
  first::return#0 = first::return#3
  to:main::@1
main::@1: scope:[main]  from main
  first::return#4 = phi( main/first::return#0 )
  main::$0 = first::return#4
  main::$1 = main::$0 + 0
  main::SCREEN[0] = *main::$1
  first::msg#1 = msg2
  call first 
  first::return#1 = first::return#3
  to:main::@2
main::@2: scope:[main]  from main::@1
  first::return#5 = phi( main::@1/first::return#1 )
  main::$2 = first::return#5
  main::$3 = main::$2 + 0
  main::SCREEN[1] = *main::$3
  to:main::@return
main::@return: scope:[main]  from main::@2
  return 
  to:@return

byte* first(byte* first::msg)
first: scope:[first]  from main main::@1
  first::msg#2 = phi( main/first::msg#0, main::@1/first::msg#1 )
  first::$0 = first::msg#2 + 0
  first::return#2 = (byte*)first::$0
  to:first::@return
first::@return: scope:[first]  from first
  first::return#6 = phi( first/first::return#2 )
  first::return#3 = first::return#6
  return 
  to:@return

void __start()
__start: scope:[__start]  from
  call main 
  to:__start::@1
__start::@1: scope:[__start]  from __start
  to:__start::@return
__start::@return: scope:[__start]  from __start::@1
  return 
  to:@return

SYMBOL TABLE SSA
void __start()
byte* first(byte* first::msg)
byte*~ first::$0
byte* first::msg
byte* first::msg#0
byte* first::msg#1
byte* first::msg#2
byte* first::return
byte* first::return#0
byte* first::return#1
byte* first::return#2
byte* first::return#3
byte* first::return#4
byte* first::return#5
byte* first::return#6
void main()
byte*~ main::$0
byte*~ main::$1
byte*~ main::$2
byte*~ main::$3
constant byte* const main::SCREEN = (byte*)$400
constant byte* msg1[]  = "hello world!"
constant byte* msg2[]  = "goodbye sky?"

Adding number conversion cast (unumber) 0 in main::$1 = main::$0 + 0
Adding number conversion cast (unumber) 0 in main::SCREEN[0] = *main::$1
Adding number conversion cast (unumber) 0 in main::$3 = main::$2 + 0
Adding number conversion cast (unumber) 1 in main::SCREEN[1] = *main::$3
Adding number conversion cast (unumber) 0 in first::$0 = first::msg#2 + 0
Successful SSA optimization PassNAddNumberTypeConversions
Simplifying constant pointer cast (byte*) 1024
Simplifying constant integer cast 0
Simplifying constant integer cast 0
Simplifying constant integer cast 0
Simplifying constant integer cast 1
Simplifying constant integer cast 0
Simplifying constant integer cast first::$0
Successful SSA optimization PassNCastSimplification
Finalized unsigned number type (byte) 0
Finalized unsigned number type (byte) 0
Finalized unsigned number type (byte) 0
Finalized unsigned number type (byte) 1
Finalized unsigned number type (byte) 0
Successful SSA optimization PassNFinalizeNumberTypeConversions
Alias first::return#0 = first::return#4 
Alias first::return#1 = first::return#5 
Alias first::return#2 = first::$0 first::return#6 first::return#3 
Successful SSA optimization Pass2AliasElimination
Constant first::msg#0 = msg1
Constant first::msg#1 = msg2
Successful SSA optimization Pass2ConstantIdentification
Converting *(pointer+n) to pointer[n] [5] main::SCREEN[0] = *main::$1  -- main::$0[0]
Converting *(pointer+n) to pointer[n] [11] main::SCREEN[1] = *main::$3  -- main::$2[0]
Successful SSA optimization Pass2InlineDerefIdx
Simplifying expression containing zero main::$0 in [4] main::$1 = main::$0 + 0
Simplifying expression containing zero main::$0 in [5] main::SCREEN[0] = main::$0[0]
Simplifying expression containing zero main::SCREEN in [5] main::SCREEN[0] = *main::$0
Simplifying expression containing zero main::$2 in [10] main::$3 = main::$2 + 0
Simplifying expression containing zero main::$2 in [11] main::SCREEN[1] = main::$2[0]
Simplifying expression containing zero first::msg#2 in [14] first::return#2 = first::msg#2 + 0
Successful SSA optimization PassNSimplifyExpressionWithZero
Eliminating unused variable main::$1 and assignment [3] main::$1 = main::$0
Eliminating unused variable main::$3 and assignment [8] main::$3 = main::$2
Successful SSA optimization PassNEliminateUnusedVars
Removing unused procedure __start
Removing unused procedure block __start
Removing unused procedure block __start::@1
Removing unused procedure block __start::@return
Successful SSA optimization PassNEliminateEmptyStart
Alias first::return#2 = first::msg#2 
Successful SSA optimization Pass2AliasElimination
Constant inlined first::msg#0 = msg1
Constant inlined first::msg#1 = msg2
Successful SSA optimization Pass2ConstantInlining
Consolidated array index constant in *(main::SCREEN+1)
Successful SSA optimization Pass2ConstantAdditionElimination
Adding NOP phi() at start of main
CALL GRAPH
Calls in [main] to first:1 first:5 

Created 1 initial phi equivalence classes
Coalesced down to 1 phi equivalence classes
Adding NOP phi() at start of main

FINAL CONTROL FLOW GRAPH

void main()
main: scope:[main]  from
  [0] phi()
  [1] call first 
  [2] first::return#0 = first::return#2
  to:main::@1
main::@1: scope:[main]  from main
  [3] main::$0 = first::return#0
  [4] *main::SCREEN = *main::$0
  [5] call first 
  [6] first::return#1 = first::return#2
  to:main::@2
main::@2: scope:[main]  from main::@1
  [7] main::$2 = first::return#1
  [8] *(main::SCREEN+1) = *main::$2
  to:main::@return
main::@return: scope:[main]  from main::@2
  [9] return 
  to:@return

byte* first(byte* first::msg)
first: scope:[first]  from main main::@1
  [10] first::return#2 = phi( main/msg1, main::@1/msg2 )
  to:first::@return
first::@return: scope:[first]  from first
  [11] return 
  to:@return


VARIABLE REGISTER WEIGHTS
byte* first(byte* first::msg)
byte* first::msg
byte* first::return
byte* first::return#0 4.0
byte* first::return#1 4.0
byte* first::return#2 1.0
void main()
byte*~ main::$0 4.0
byte*~ main::$2 4.0

Initial phi equivalence classes
[ first::return#2 ]
Added variable first::return#0 to live range equivalence class [ first::return#0 ]
Added variable main::$0 to live range equivalence class [ main::$0 ]
Added variable first::return#1 to live range equivalence class [ first::return#1 ]
Added variable main::$2 to live range equivalence class [ main::$2 ]
Complete equivalence classes
[ first::return#2 ]
[ first::return#0 ]
[ main::$0 ]
[ first::return#1 ]
[ main::$2 ]
Allocated zp[2]:2 [ first::return#2 ]
Allocated zp[2]:4 [ first::return#0 ]
Allocated zp[2]:6 [ main::$0 ]
Allocated zp[2]:8 [ first::return#1 ]
Allocated zp[2]:10 [ main::$2 ]
REGISTER UPLIFT POTENTIAL REGISTERS
Statement [2] first::return#0 = first::return#2 [ first::return#0 ] (  [ first::return#0 ] { { first::return#0 = first::return#2 } }  ) always clobbers reg byte a 
Statement [3] main::$0 = first::return#0 [ main::$0 ] (  [ main::$0 ] { { first::return#1 = first::return#2 } }  ) always clobbers reg byte a 
Statement [4] *main::SCREEN = *main::$0 [ ] (  [ ] { { first::return#1 = first::return#2 } }  ) always clobbers reg byte a reg byte y 
Statement [6] first::return#1 = first::return#2 [ first::return#1 ] (  [ first::return#1 ] { { first::return#1 = first::return#2 } }  ) always clobbers reg byte a 
Statement [7] main::$2 = first::return#1 [ main::$2 ] (  [ main::$2 ] { }  ) always clobbers reg byte a 
Statement [8] *(main::SCREEN+1) = *main::$2 [ ] (  [ ] { }  ) always clobbers reg byte a reg byte y 
Potential registers zp[2]:2 [ first::return#2 ] : zp[2]:2 , 
Potential registers zp[2]:4 [ first::return#0 ] : zp[2]:4 , 
Potential registers zp[2]:6 [ main::$0 ] : zp[2]:6 , 
Potential registers zp[2]:8 [ first::return#1 ] : zp[2]:8 , 
Potential registers zp[2]:10 [ main::$2 ] : zp[2]:10 , 

REGISTER UPLIFT SCOPES
Uplift Scope [first] 4: zp[2]:4 [ first::return#0 ] 4: zp[2]:8 [ first::return#1 ] 1: zp[2]:2 [ first::return#2 ] 
Uplift Scope [main] 4: zp[2]:6 [ main::$0 ] 4: zp[2]:10 [ main::$2 ] 
Uplift Scope [] 

Uplifting [first] best 153 combination zp[2]:4 [ first::return#0 ] zp[2]:8 [ first::return#1 ] zp[2]:2 [ first::return#2 ] 
Uplifting [main] best 153 combination zp[2]:6 [ main::$0 ] zp[2]:10 [ main::$2 ] 
Uplifting [] best 153 combination 
Coalescing zero page register [ zp[2]:2 [ first::return#2 ] ] with [ zp[2]:4 [ first::return#0 ] ] - score: 1
Coalescing zero page register [ zp[2]:2 [ first::return#2 first::return#0 ] ] with [ zp[2]:8 [ first::return#1 ] ] - score: 1
Coalescing zero page register [ zp[2]:2 [ first::return#2 first::return#0 first::return#1 ] ] with [ zp[2]:6 [ main::$0 ] ] - score: 1
Coalescing zero page register [ zp[2]:2 [ first::return#2 first::return#0 first::return#1 main::$0 ] ] with [ zp[2]:10 [ main::$2 ] ] - score: 1

ASSEMBLER BEFORE OPTIMIZATION
  // File Comments
// Tests pointer plus 0 elimination
  // Upstart
  // Commodore 64 PRG executable file
.file [name="pointer-plus-0.prg", type="prg", segments="Program"]
.segmentdef Program [segments="Basic, Code, Data"]
.segmentdef Basic [start=$0801]
.segmentdef Code [start=$80d]
.segmentdef Data [startAfter="Code"]
.segment Basic
:BasicUpstart(main)
  // Global Constants & labels
.segment Code
  // main
main: {
    .label SCREEN = $400
    .label __0 = 2
    .label __2 = 2
    // [1] call first 
    // [10] phi from main to first [phi:main->first]
  first_from_main:
    // [10] phi first::return#2 = msg1 [phi:main->first#0] -- pbuz1=pbuc1 
    lda #<msg1
    sta.z first.return
    lda #>msg1
    sta.z first.return+1
    jsr first
    // [2] first::return#0 = first::return#2
    jmp __b1
    // main::@1
  __b1:
    // [3] main::$0 = first::return#0
    // [4] *main::SCREEN = *main::$0 -- _deref_pbuc1=_deref_pbuz1 
    ldy #0
    lda (__0),y
    sta SCREEN
    // [5] call first 
    // [10] phi from main::@1 to first [phi:main::@1->first]
  first_from___b1:
    // [10] phi first::return#2 = msg2 [phi:main::@1->first#0] -- pbuz1=pbuc1 
    lda #<msg2
    sta.z first.return
    lda #>msg2
    sta.z first.return+1
    jsr first
    // [6] first::return#1 = first::return#2
    jmp __b2
    // main::@2
  __b2:
    // [7] main::$2 = first::return#1
    // [8] *(main::SCREEN+1) = *main::$2 -- _deref_pbuc1=_deref_pbuz1 
    ldy #0
    lda (__2),y
    sta SCREEN+1
    jmp __breturn
    // main::@return
  __breturn:
    // [9] return 
    rts
}
  // first
first: {
    .label return = 2
    jmp __breturn
    // first::@return
  __breturn:
    // [11] return 
    rts
}
  // File Data
.segment Data
  msg1: .text "hello world!"
  .byte 0
  msg2: .text "goodbye sky?"
  .byte 0

ASSEMBLER OPTIMIZATIONS
Removing instruction jmp __b1
Removing instruction jmp __b2
Removing instruction jmp __breturn
Removing instruction jmp __breturn
Succesful ASM optimization Pass5NextJumpElimination
Removing instruction first_from_main:
Removing instruction __b1:
Removing instruction first_from___b1:
Removing instruction __b2:
Removing instruction __breturn:
Removing instruction __breturn:
Succesful ASM optimization Pass5UnusedLabelElimination

FINAL SYMBOL TABLE
byte* first(byte* first::msg)
byte* first::msg
byte* first::return
byte* first::return#0 return zp[2]:2 4.0
byte* first::return#1 return zp[2]:2 4.0
byte* first::return#2 return zp[2]:2 1.0
void main()
byte*~ main::$0 zp[2]:2 4.0
byte*~ main::$2 zp[2]:2 4.0
constant byte* const main::SCREEN = (byte*) 1024
constant byte* msg1[]  = "hello world!"
constant byte* msg2[]  = "goodbye sky?"

zp[2]:2 [ first::return#2 first::return#0 first::return#1 main::$0 main::$2 ]


FINAL ASSEMBLER
Score: 66

  // File Comments
// Tests pointer plus 0 elimination
  // Upstart
  // Commodore 64 PRG executable file
.file [name="pointer-plus-0.prg", type="prg", segments="Program"]
.segmentdef Program [segments="Basic, Code, Data"]
.segmentdef Basic [start=$0801]
.segmentdef Code [start=$80d]
.segmentdef Data [startAfter="Code"]
.segment Basic
:BasicUpstart(main)
  // Global Constants & labels
.segment Code
  // main
main: {
    .label SCREEN = $400
    .label __0 = 2
    .label __2 = 2
    // first(msg1)
    // [1] call first 
    // [10] phi from main to first [phi:main->first]
    // [10] phi first::return#2 = msg1 [phi:main->first#0] -- pbuz1=pbuc1 
    lda #<msg1
    sta.z first.return
    lda #>msg1
    sta.z first.return+1
    jsr first
    // first(msg1)
    // [2] first::return#0 = first::return#2
    // main::@1
    // [3] main::$0 = first::return#0
    // SCREEN[0] = *(first(msg1)+0)
    // [4] *main::SCREEN = *main::$0 -- _deref_pbuc1=_deref_pbuz1 
    ldy #0
    lda (__0),y
    sta SCREEN
    // first(msg2)
    // [5] call first 
    // [10] phi from main::@1 to first [phi:main::@1->first]
    // [10] phi first::return#2 = msg2 [phi:main::@1->first#0] -- pbuz1=pbuc1 
    lda #<msg2
    sta.z first.return
    lda #>msg2
    sta.z first.return+1
    jsr first
    // first(msg2)
    // [6] first::return#1 = first::return#2
    // main::@2
    // [7] main::$2 = first::return#1
    // SCREEN[1] = *(first(msg2)+0)
    // [8] *(main::SCREEN+1) = *main::$2 -- _deref_pbuc1=_deref_pbuz1 
    ldy #0
    lda (__2),y
    sta SCREEN+1
    // main::@return
    // }
    // [9] return 
    rts
}
  // first
first: {
    .label return = 2
    // first::@return
    // [11] return 
    rts
}
  // File Data
.segment Data
  msg1: .text "hello world!"
  .byte 0
  msg2: .text "goodbye sky?"
  .byte 0