CONTROL FLOW GRAPH SSA @begin: scope:[] from (byte*) screen#0 ← (byte*) 0 to:@1 (void()) main() main: scope:[main] from @1 (byte*) screen#1 ← ((byte*)) (number) $400 *((byte*) screen#1) ← (byte) 'a' to:main::@return main::@return: scope:[main] from main (byte*) screen#4 ← phi( main/(byte*) screen#1 ) (byte*) screen#2 ← (byte*) screen#4 return to:@return @1: scope:[] from @begin (byte*) screen#6 ← phi( @begin/(byte*) screen#0 ) call main to:@2 @2: scope:[] from @1 (byte*) screen#5 ← phi( @1/(byte*) screen#2 ) (byte*) screen#3 ← (byte*) screen#5 to:@end @end: scope:[] from @2 SYMBOL TABLE SSA (label) @1 (label) @2 (label) @begin (label) @end (void()) main() (label) main::@return (byte*) screen (byte*) screen#0 (byte*) screen#1 (byte*) screen#2 (byte*) screen#3 (byte*) screen#4 (byte*) screen#5 (byte*) screen#6 Inlining cast (byte*) screen#1 ← (byte*)(number) $400 Successful SSA optimization Pass2InlineCast Simplifying constant pointer cast (byte*) 1024 Successful SSA optimization PassNCastSimplification Alias (byte*) screen#1 = (byte*) screen#4 (byte*) screen#2 Alias (byte*) screen#0 = (byte*) screen#6 Alias (byte*) screen#3 = (byte*) screen#5 Successful SSA optimization Pass2AliasElimination Identical Phi Values (byte*) screen#3 (byte*) screen#1 Successful SSA optimization Pass2IdenticalPhiElimination Constant (const byte*) screen#0 = (byte*) 0 Constant (const byte*) screen#1 = (byte*) 1024 Successful SSA optimization Pass2ConstantIdentification Eliminating unused constant (const byte*) screen#0 Successful SSA optimization PassNEliminateUnusedVars Adding NOP phi() at start of @begin Adding NOP phi() at start of @1 Adding NOP phi() at start of @2 Adding NOP phi() at start of @end CALL GRAPH Calls in [] to main:2 Created 0 initial phi equivalence classes Coalesced down to 0 phi equivalence classes Culled Empty Block (label) @2 Adding NOP phi() at start of @begin Adding NOP phi() at start of @1 Adding NOP phi() at start of @end FINAL CONTROL FLOW GRAPH @begin: scope:[] from [0] phi() to:@1 @1: scope:[] from @begin [1] phi() [2] call main to:@end @end: scope:[] from @1 [3] phi() (void()) main() main: scope:[main] from @1 [4] *((const byte*) screen#1) ← (byte) 'a' to:main::@return main::@return: scope:[main] from main [5] return to:@return VARIABLE REGISTER WEIGHTS (void()) main() (byte*) screen Initial phi equivalence classes Complete equivalence classes INITIAL ASM Target platform is c64basic / MOS6502X // File Comments // Variables without initialization causes problems when compiling // Upstart .pc = $801 "Basic" :BasicUpstart(__bbegin) .pc = $80d "Program" // Global Constants & labels .label screen = $400 // @begin __bbegin: // [1] phi from @begin to @1 [phi:@begin->@1] __b1_from___bbegin: jmp __b1 // @1 __b1: // [2] call main jsr main // [3] phi from @1 to @end [phi:@1->@end] __bend_from___b1: jmp __bend // @end __bend: // main main: { // [4] *((const byte*) screen#1) ← (byte) 'a' -- _deref_pbuc1=vbuc2 lda #'a' sta screen jmp __breturn // main::@return __breturn: // [5] return rts } // File Data REGISTER UPLIFT POTENTIAL REGISTERS Statement [4] *((const byte*) screen#1) ← (byte) 'a' [ ] ( main:2 [ ] ) always clobbers reg byte a REGISTER UPLIFT SCOPES Uplift Scope [main] Uplift Scope [] Uplifting [main] best 27 combination Uplifting [] best 27 combination ASSEMBLER BEFORE OPTIMIZATION // File Comments // Variables without initialization causes problems when compiling // Upstart .pc = $801 "Basic" :BasicUpstart(__bbegin) .pc = $80d "Program" // Global Constants & labels .label screen = $400 // @begin __bbegin: // [1] phi from @begin to @1 [phi:@begin->@1] __b1_from___bbegin: jmp __b1 // @1 __b1: // [2] call main jsr main // [3] phi from @1 to @end [phi:@1->@end] __bend_from___b1: jmp __bend // @end __bend: // main main: { // [4] *((const byte*) screen#1) ← (byte) 'a' -- _deref_pbuc1=vbuc2 lda #'a' sta screen jmp __breturn // main::@return __breturn: // [5] return rts } // File Data ASSEMBLER OPTIMIZATIONS Removing instruction jmp __b1 Removing instruction jmp __bend Removing instruction jmp __breturn Succesful ASM optimization Pass5NextJumpElimination Replacing label __bbegin with __b1 Removing instruction __bbegin: Removing instruction __b1_from___bbegin: Removing instruction __bend_from___b1: Succesful ASM optimization Pass5RedundantLabelElimination Removing instruction __bend: Removing instruction __breturn: Succesful ASM optimization Pass5UnusedLabelElimination Updating BasicUpstart to call main directly Removing instruction jsr main Succesful ASM optimization Pass5SkipBegin Removing instruction __b1: Succesful ASM optimization Pass5UnusedLabelElimination FINAL SYMBOL TABLE (label) @1 (label) @begin (label) @end (void()) main() (label) main::@return (byte*) screen (const byte*) screen#1 screen = (byte*) 1024 FINAL ASSEMBLER Score: 12 // File Comments // Variables without initialization causes problems when compiling // Upstart .pc = $801 "Basic" :BasicUpstart(main) .pc = $80d "Program" // Global Constants & labels .label screen = $400 // @begin // [1] phi from @begin to @1 [phi:@begin->@1] // @1 // [2] call main // [3] phi from @1 to @end [phi:@1->@end] // @end // main main: { // *screen = 'a' // [4] *((const byte*) screen#1) ← (byte) 'a' -- _deref_pbuc1=vbuc2 lda #'a' sta screen // main::@return // } // [5] return rts } // File Data