CONTROL FLOW GRAPH SSA void main() main: scope:[main] from __start main::i#0 = 0 to:main::@1 main::@1: scope:[main] from main main::@2 main::i#2 = phi( main/main::i#0, main::@2/main::i#1 ) main::$0 = main::i#2 < $a if(main::$0) goto main::@2 to:main::@return main::@2: scope:[main] from main::@1 main::i#3 = phi( main::@1/main::i#2 ) main::$2 = (char)main::i#3 main::$1 = main::$2 * SIZEOF_INT main::SCREEN[main::$1] = main::i#3 main::i#1 = ++ main::i#3 to:main::@1 main::@return: scope:[main] from main::@1 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 __constant char SIZEOF_INT = 2 void __start() void main() bool main::$0 char main::$1 char main::$2 __constant int * const main::SCREEN = (int *)$400 int main::i int main::i#0 int main::i#1 int main::i#2 int main::i#3 Adding number conversion cast (snumber) $a in main::$0 = main::i#2 < $a Successful SSA optimization PassNAddNumberTypeConversions Simplifying constant pointer cast (int *) 1024 Simplifying constant integer cast $a Successful SSA optimization PassNCastSimplification Finalized signed number type (signed char) $a Successful SSA optimization PassNFinalizeNumberTypeConversions Alias main::i#2 = main::i#3 Successful SSA optimization Pass2AliasElimination Simple Condition main::$0 [3] if(main::i#2<$a) goto main::@2 Successful SSA optimization Pass2ConditionalJumpSimplification Constant main::i#0 = 0 Successful SSA optimization Pass2ConstantIdentification 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 Rewriting multiplication to use shift [3] main::$1 = main::$2 * SIZEOF_INT Successful SSA optimization Pass2MultiplyToShiftRewriting Inlining constant with var siblings main::i#0 Constant inlined main::i#0 = 0 Successful SSA optimization Pass2ConstantInlining Eliminating unused constant SIZEOF_INT Successful SSA optimization PassNEliminateUnusedVars Adding NOP phi() at start of main CALL GRAPH Created 1 initial phi equivalence classes Coalesced [8] main::i#4 = main::i#1 Coalesced down to 1 phi equivalence classes Adding NOP phi() at start of main FINAL CONTROL FLOW GRAPH void main() main: scope:[main] from [0] phi() to:main::@1 main::@1: scope:[main] from main main::@2 [1] main::i#2 = phi( main/0, main::@2/main::i#1 ) [2] if(main::i#2<$a) goto main::@2 to:main::@return main::@return: scope:[main] from main::@1 [3] return to:@return main::@2: scope:[main] from main::@1 [4] main::$2 = (char)main::i#2 [5] main::$1 = main::$2 << 1 [6] main::SCREEN[main::$1] = main::i#2 [7] main::i#1 = ++ main::i#2 to:main::@1 VARIABLE REGISTER WEIGHTS void main() char main::$1 // 22.0 char main::$2 // 22.0 int main::i int main::i#1 // 22.0 int main::i#2 // 8.8 Initial phi equivalence classes [ main::i#2 main::i#1 ] Added variable main::$2 to live range equivalence class [ main::$2 ] Added variable main::$1 to live range equivalence class [ main::$1 ] Complete equivalence classes [ main::i#2 main::i#1 ] [ main::$2 ] [ main::$1 ] Zero-page exhausted. Moving allocation to main memory main::i#2 Allocated mem[2] [ main::i#2 main::i#1 ] Zero-page exhausted. Moving allocation to main memory main::$2 Allocated mem[1] [ main::$2 ] Zero-page exhausted. Moving allocation to main memory main::$1 Allocated mem[1] [ main::$1 ] REGISTER UPLIFT POTENTIAL REGISTERS Statement [2] if(main::i#2<$a) goto main::@2 [ main::i#2 ] ( [ main::i#2 ] { } ) always clobbers reg byte a Statement [4] main::$2 = (char)main::i#2 [ main::i#2 main::$2 ] ( [ main::i#2 main::$2 ] { } ) always clobbers reg byte a Statement [5] main::$1 = main::$2 << 1 [ main::i#2 main::$1 ] ( [ main::i#2 main::$1 ] { } ) always clobbers reg byte a Statement [6] main::SCREEN[main::$1] = main::i#2 [ main::i#2 ] ( [ main::i#2 ] { } ) always clobbers reg byte a Potential registers mem[2] [ main::i#2 main::i#1 ] : mem[2] , Potential registers mem[1] [ main::$2 ] : mem[1] , reg byte a , reg byte x , reg byte y , Potential registers mem[1] [ main::$1 ] : mem[1] , reg byte a , reg byte x , reg byte y , REGISTER UPLIFT SCOPES Uplift Scope [main] 30.8: mem[2] [ main::i#2 main::i#1 ] 22: mem[1] [ main::$2 ] 22: mem[1] [ main::$1 ] Uplift Scope [] Uplifting [main] best 841 combination mem[2] [ main::i#2 main::i#1 ] reg byte a [ main::$2 ] reg byte a [ main::$1 ] Uplifting [] best 841 combination Zero-page exhausted. Moving allocation to main memory main::i#2 ASSEMBLER BEFORE OPTIMIZATION // File Comments // Tests warning when running out of zeropage-addresses for variables // Upstart // Commodore 64 PRG executable file .file [name="zeropage-exhausted.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 // And then allocate a 2-byte-variable main: { .label SCREEN = $400 // [1] phi from main to main::@1 [phi:main->main::@1] __b1_from_main: // [1] phi main::i#2 = 0 [phi:main->main::@1#0] -- vwsm1=vwsc1 lda #<0 sta i lda #>0 sta i+1 jmp __b1 // main::@1 __b1: // [2] if(main::i#2<$a) goto main::@2 -- vwsm1_lt_vwuc1_then_la1 lda i+1 bmi __b2 cmp #>$a bcc __b2 bne !+ lda i cmp #<$a bcc __b2 !: jmp __breturn // main::@return __breturn: // [3] return rts // main::@2 __b2: // [4] main::$2 = (char)main::i#2 -- vbuaa=_byte_vwsm1 lda i // [5] main::$1 = main::$2 << 1 -- vbuaa=vbuaa_rol_1 asl // [6] main::SCREEN[main::$1] = main::i#2 -- pwsc1_derefidx_vbuaa=vwsm1 tay lda i sta SCREEN,y lda i+1 sta SCREEN+1,y // [7] main::i#1 = ++ main::i#2 -- vwsm1=_inc_vwsm1 inc i bne !+ inc i+1 !: // [1] phi from main::@2 to main::@1 [phi:main::@2->main::@1] __b1_from___b2: // [1] phi main::i#2 = main::i#1 [phi:main::@2->main::@1#0] -- register_copy jmp __b1 .segment Data i: .word 0 } // File Data ASSEMBLER OPTIMIZATIONS Removing instruction jmp __b1 Removing instruction jmp __breturn Succesful ASM optimization Pass5NextJumpElimination Removing instruction lda #>0 Succesful ASM optimization Pass5UnnecesaryLoadElimination Removing instruction __b1_from_main: Removing instruction __breturn: Removing instruction __b1_from___b2: Succesful ASM optimization Pass5UnusedLabelElimination FINAL SYMBOL TABLE void main() char main::$1 // reg byte a 22.0 char main::$2 // reg byte a 22.0 __constant int * const main::SCREEN = (int *) 1024 int main::i int main::i#1 // i mem[2] 22.0 int main::i#2 // i mem[2] 8.8 mem[2] [ main::i#2 main::i#1 ] reg byte a [ main::$2 ] reg byte a [ main::$1 ] FINAL ASSEMBLER Score: 761 // File Comments // Tests warning when running out of zeropage-addresses for variables // Upstart // Commodore 64 PRG executable file .file [name="zeropage-exhausted.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 // And then allocate a 2-byte-variable main: { .label SCREEN = $400 // [1] phi from main to main::@1 [phi:main->main::@1] // [1] phi main::i#2 = 0 [phi:main->main::@1#0] -- vwsm1=vwsc1 lda #<0 sta i sta i+1 // main::@1 __b1: // for(__zp int i=0;i<10;i++) // [2] if(main::i#2<$a) goto main::@2 -- vwsm1_lt_vwuc1_then_la1 lda i+1 bmi __b2 cmp #>$a bcc __b2 bne !+ lda i cmp #<$a bcc __b2 !: // main::@return // } // [3] return rts // main::@2 __b2: // SCREEN[(char)i] = i // [4] main::$2 = (char)main::i#2 -- vbuaa=_byte_vwsm1 lda i // [5] main::$1 = main::$2 << 1 -- vbuaa=vbuaa_rol_1 asl // [6] main::SCREEN[main::$1] = main::i#2 -- pwsc1_derefidx_vbuaa=vwsm1 tay lda i sta SCREEN,y lda i+1 sta SCREEN+1,y // for(__zp int i=0;i<10;i++) // [7] main::i#1 = ++ main::i#2 -- vwsm1=_inc_vwsm1 inc i bne !+ inc i+1 !: // [1] phi from main::@2 to main::@1 [phi:main::@2->main::@1] // [1] phi main::i#2 = main::i#1 [phi:main::@2->main::@1#0] -- register_copy jmp __b1 .segment Data i: .word 0 } // File Data