Merge remote-tracking branch 'origin/328-memvars' into 328-memvars

2024-12-28 01:29:44 +00:00 · 2019-10-31 22:48:24 +01:00 · 2019-10-31 22:48:24 +01:00 · 445f104309
commit 445f104309
parent db60a5e2a4 e427cb648b
7 changed files with 652 additions and 1 deletions
--- a/src/main/java/dk/camelot64/kickc/asm/AsmProgramStaticRegisterValues.java
+++ b/src/main/java/dk/camelot64/kickc/asm/AsmProgramStaticRegisterValues.java
@ -31,7 +31,7 @@ public class AsmProgramStaticRegisterValues {
         } else if(parameter.startsWith(">")) {
            try {
               int parValue = Integer.parseInt(parameter.substring(1));
-               return 0xff & (parValue / 0x100);
+               return 0xff & ((parValue & 0xffff) / 0x100);
            } catch(NumberFormatException e) {
               // ignore
            }
--- a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
+++ b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
@ -37,6 +37,11 @@ public class TestPrograms {
   public TestPrograms() {
   }

+   @Test
+   public void testStaticRegisterOptimizationProblem() throws IOException, URISyntaxException {
+      compileAndCompare("static-register-optimization-problem");
+   }
+
   @Test
   public void testDeclaredNotConstVar1() throws IOException, URISyntaxException {
      compileAndCompare("declared-notconst-var-1");
--- a/src/test/kc/static-register-optimization-problem.kc
+++ b/src/test/kc/static-register-optimization-problem.kc
@ -0,0 +1,11 @@
+// https://gitlab.com/camelot/kickc/issues/336
+// ASM Static Register Value analysis erronously believes >-1 == 0
+
+void main() {
+    char* screen = 0x0400;
+    int lasti = -1;
+    for(int i=0;i<10;i++) {
+        screen[i] = <lasti;
+        lasti = i;
+    }
+}
--- a/src/test/ref/static-register-optimization-problem.asm
+++ b/src/test/ref/static-register-optimization-problem.asm
@ -0,0 +1,50 @@
+// https://gitlab.com/camelot/kickc/issues/336
+// ASM Static Register Value analysis erronously believes >-1 == 0
+.pc = $801 "Basic"
+:BasicUpstart(main)
+.pc = $80d "Program"
+main: {
+    .label screen = $400
+    .label lasti = 4
+    .label i = 2
+    .label __2 = 6
+    lda #<-1
+    sta.z lasti
+    sta.z lasti+1
+    lda #<0
+    sta.z i
+    sta.z i+1
+  __b1:
+    lda.z i+1
+    bmi __b2
+    cmp #>$a
+    bcc __b2
+    bne !+
+    lda.z i
+    cmp #<$a
+    bcc __b2
+  !:
+    rts
+  __b2:
+    lda.z lasti
+    tax
+    lda #<screen
+    clc
+    adc.z i
+    sta.z __2
+    lda #>screen
+    adc.z i+1
+    sta.z __2+1
+    txa
+    ldy #0
+    sta (__2),y
+    lda.z i
+    sta.z lasti
+    lda.z i+1
+    sta.z lasti+1
+    inc.z i
+    bne !+
+    inc.z i+1
+  !:
+    jmp __b1
+}
--- a/src/test/ref/static-register-optimization-problem.cfg
+++ b/src/test/ref/static-register-optimization-problem.cfg
@ -0,0 +1,29 @@
+@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] phi()
+  to:main::@1
+main::@1: scope:[main]  from main main::@2
+  [5] (signed word) main::lasti#2 ← phi( main/(signed byte) -1 main::@2/(signed word) main::lasti#1 )
+  [5] (signed word) main::i#2 ← phi( main/(signed byte) 0 main::@2/(signed word) main::i#1 )
+  [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2
+  to:main::@return
+main::@return: scope:[main]  from main::@1
+  [7] return 
+  to:@return
+main::@2: scope:[main]  from main::@1
+  [8] (byte~) main::$1 ← < (signed word) main::lasti#2
+  [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2
+  [10] *((byte*~) main::$2) ← (byte~) main::$1
+  [11] (signed word) main::lasti#1 ← (signed word) main::i#2
+  [12] (signed word) main::i#1 ← ++ (signed word) main::i#2
+  to:main::@1
--- a/src/test/ref/static-register-optimization-problem.log
+++ b/src/test/ref/static-register-optimization-problem.log
@ -0,0 +1,535 @@
+Identified constant variable (byte*) main::screen
+Culled Empty Block (label) main::@4
+Culled Empty Block (label) main::@3
+Culled Empty Block (label) main::@5
+Culled Empty Block (label) main::@6
+
+CONTROL FLOW GRAPH SSA
+@begin: scope:[]  from
+  to:@1
+
+(void()) main()
+main: scope:[main]  from @1
+  (byte*) main::screen ← ((byte*)) (number) $400
+  (signed word) main::lasti#0 ← (number) -1
+  (signed word) main::i#0 ← (number) 0
+  to:main::@1
+main::@1: scope:[main]  from main main::@2
+  (signed word) main::lasti#3 ← phi( main/(signed word) main::lasti#0 main::@2/(signed word) main::lasti#1 )
+  (signed word) main::i#2 ← phi( main/(signed word) main::i#0 main::@2/(signed word) main::i#1 )
+  (bool~) main::$0 ← (signed word) main::i#2 < (number) $a
+  if((bool~) main::$0) goto main::@2
+  to:main::@return
+main::@2: scope:[main]  from main::@1
+  (signed word) main::i#3 ← phi( main::@1/(signed word) main::i#2 )
+  (signed word) main::lasti#2 ← phi( main::@1/(signed word) main::lasti#3 )
+  (byte~) main::$1 ← < (signed word) main::lasti#2
+  *((byte*) main::screen + (signed word) main::i#3) ← (byte~) main::$1
+  (signed word) main::lasti#1 ← (signed word) main::i#3
+  (signed word) main::i#1 ← ++ (signed word) main::i#3
+  to:main::@1
+main::@return: scope:[main]  from main::@1
+  return 
+  to:@return
+@1: scope:[]  from @begin
+  call main 
+  to:@2
+@2: scope:[]  from @1
+  to:@end
+@end: scope:[]  from @2
+
+SYMBOL TABLE SSA
+(label) @1
+(label) @2
+(label) @begin
+(label) @end
+(void()) main()
+(bool~) main::$0
+(byte~) main::$1
+(label) main::@1
+(label) main::@2
+(label) main::@return
+(signed word) main::i
+(signed word) main::i#0
+(signed word) main::i#1
+(signed word) main::i#2
+(signed word) main::i#3
+(signed word) main::lasti
+(signed word) main::lasti#0
+(signed word) main::lasti#1
+(signed word) main::lasti#2
+(signed word) main::lasti#3
+(byte*) main::screen
+
+Adding number conversion cast (snumber) -1 in (signed word) main::lasti#0 ← (number) -1
+Adding number conversion cast (snumber) 0 in (signed word) main::i#0 ← (number) 0
+Adding number conversion cast (snumber) $a in (bool~) main::$0 ← (signed word) main::i#2 < (number) $a
+Successful SSA optimization PassNAddNumberTypeConversions
+Inlining cast (byte*) main::screen ← (byte*)(number) $400
+Inlining cast (signed word) main::lasti#0 ← (snumber)(number) -1
+Inlining cast (signed word) main::i#0 ← (snumber)(number) 0
+Successful SSA optimization Pass2InlineCast
+Simplifying constant pointer cast (byte*) 1024
+Simplifying constant integer cast -1
+Simplifying constant integer cast 0
+Simplifying constant integer cast $a
+Successful SSA optimization PassNCastSimplification
+Finalized signed number type (signed byte) -1
+Finalized signed number type (signed byte) 0
+Finalized signed number type (signed byte) $a
+Successful SSA optimization PassNFinalizeNumberTypeConversions
+Alias candidate removed (phi-usage) (signed word) main::i#2 = (signed word) main::i#3 (signed word) main::lasti#1 
+Alias (signed word) main::lasti#2 = (signed word) main::lasti#3 
+Successful SSA optimization Pass2AliasElimination
+Alias candidate removed (phi-usage) (signed word) main::i#2 = (signed word) main::i#3 (signed word) main::lasti#1 
+Identical Phi Values (signed word) main::i#3 (signed word) main::i#2
+Successful SSA optimization Pass2IdenticalPhiElimination
+Simple Condition (bool~) main::$0 [5] if((signed word) main::i#2<(signed byte) $a) goto main::@2
+Successful SSA optimization Pass2ConditionalJumpSimplification
+Constant (const byte*) main::screen = (byte*) 1024
+Constant (const signed word) main::lasti#0 = -1
+Constant (const signed word) main::i#0 = 0
+Successful SSA optimization Pass2ConstantIdentification
+De-inlining pointer[w] to *(pointer+w)   [8] *((const byte*) main::screen + (signed word) main::i#2) ← (byte~) main::$1
+Successful SSA optimization Pass2DeInlineWordDerefIdx
+Alias candidate removed (phi-usage) (signed word) main::lasti#1 = (signed word) main::i#2 
+Inlining constant with var siblings (const signed word) main::lasti#0
+Inlining constant with var siblings (const signed word) main::i#0
+Constant inlined main::i#0 = (signed byte) 0
+Constant inlined main::lasti#0 = (signed byte) -1
+Successful SSA optimization Pass2ConstantInlining
+Alias candidate removed (phi-usage) (signed word) main::lasti#1 = (signed word) main::i#2 
+Alias candidate removed (phi-usage) (signed word) main::lasti#1 = (signed word) main::i#2 
+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
+Adding NOP phi() at start of main
+CALL GRAPH
+Calls in [] to main:2 
+
+Created 2 initial phi equivalence classes
+Coalesced [14] main::i#4 ← main::i#1
+Coalesced [15] main::lasti#4 ← main::lasti#1
+Coalesced down to 2 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
+Adding NOP phi() at start of main
+
+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] phi()
+  to:main::@1
+main::@1: scope:[main]  from main main::@2
+  [5] (signed word) main::lasti#2 ← phi( main/(signed byte) -1 main::@2/(signed word) main::lasti#1 )
+  [5] (signed word) main::i#2 ← phi( main/(signed byte) 0 main::@2/(signed word) main::i#1 )
+  [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2
+  to:main::@return
+main::@return: scope:[main]  from main::@1
+  [7] return 
+  to:@return
+main::@2: scope:[main]  from main::@1
+  [8] (byte~) main::$1 ← < (signed word) main::lasti#2
+  [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2
+  [10] *((byte*~) main::$2) ← (byte~) main::$1
+  [11] (signed word) main::lasti#1 ← (signed word) main::i#2
+  [12] (signed word) main::i#1 ← ++ (signed word) main::i#2
+  to:main::@1
+
+
+VARIABLE REGISTER WEIGHTS
+(void()) main()
+(byte~) main::$1 11.0
+(byte*~) main::$2 22.0
+(signed word) main::i
+(signed word) main::i#1 22.0
+(signed word) main::i#2 9.166666666666666
+(signed word) main::lasti
+(signed word) main::lasti#1 11.0
+(signed word) main::lasti#2 11.0
+
+Initial phi equivalence classes
+[ main::i#2 main::i#1 ]
+[ main::lasti#2 main::lasti#1 ]
+Added variable main::$1 to zero page equivalence class [ main::$1 ]
+Added variable main::$2 to zero page equivalence class [ main::$2 ]
+Complete equivalence classes
+[ main::i#2 main::i#1 ]
+[ main::lasti#2 main::lasti#1 ]
+[ main::$1 ]
+[ main::$2 ]
+Allocated zp[2]:2 [ main::i#2 main::i#1 ]
+Allocated zp[2]:4 [ main::lasti#2 main::lasti#1 ]
+Allocated zp[1]:6 [ main::$1 ]
+Allocated zp[2]:7 [ main::$2 ]
+
+INITIAL ASM
+Target platform is c64basic / MOS6502X
+  // File Comments
+// https://gitlab.com/camelot/kickc/issues/336
+// ASM Static Register Value analysis erronously believes >-1 == 0
+  // Upstart
+.pc = $801 "Basic"
+:BasicUpstart(__bbegin)
+.pc = $80d "Program"
+  // Global Constants & labels
+  // @begin
+__bbegin:
+  // [1] phi from @begin to @1 [phi:@begin->@1]
+__b1_from___bbegin:
+  jmp __b1
+  // @1
+__b1:
+  // [2] call main 
+  // [4] phi from @1 to main [phi:@1->main]
+main_from___b1:
+  jsr main
+  // [3] phi from @1 to @end [phi:@1->@end]
+__bend_from___b1:
+  jmp __bend
+  // @end
+__bend:
+  // main
+main: {
+    .label screen = $400
+    .label __1 = 6
+    .label lasti = 4
+    .label i = 2
+    .label __2 = 7
+    // [5] phi from main to main::@1 [phi:main->main::@1]
+  __b1_from_main:
+    // [5] phi (signed word) main::lasti#2 = (signed byte) -1 [phi:main->main::@1#0] -- vwsz1=vbsc1 
+    lda #<-1
+    sta.z lasti
+    lda #>-1
+    sta.z lasti+1
+    // [5] phi (signed word) main::i#2 = (signed byte) 0 [phi:main->main::@1#1] -- vwsz1=vbsc1 
+    lda #<0
+    sta.z i
+    lda #>0
+    sta.z i+1
+    jmp __b1
+    // main::@1
+  __b1:
+    // [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2 -- vwsz1_lt_vwuc1_then_la1 
+    lda.z i+1
+    bmi __b2
+    cmp #>$a
+    bcc __b2
+    bne !+
+    lda.z i
+    cmp #<$a
+    bcc __b2
+  !:
+    jmp __breturn
+    // main::@return
+  __breturn:
+    // [7] return 
+    rts
+    // main::@2
+  __b2:
+    // [8] (byte~) main::$1 ← < (signed word) main::lasti#2 -- vbuz1=_lo_vwsz2 
+    lda.z lasti
+    sta.z __1
+    // [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2 -- pbuz1=pbuc1_plus_vwsz2 
+    lda #<screen
+    clc
+    adc.z i
+    sta.z __2
+    lda #>screen
+    adc.z i+1
+    sta.z __2+1
+    // [10] *((byte*~) main::$2) ← (byte~) main::$1 -- _deref_pbuz1=vbuz2 
+    lda.z __1
+    ldy #0
+    sta (__2),y
+    // [11] (signed word) main::lasti#1 ← (signed word) main::i#2 -- vwsz1=vwsz2 
+    lda.z i
+    sta.z lasti
+    lda.z i+1
+    sta.z lasti+1
+    // [12] (signed word) main::i#1 ← ++ (signed word) main::i#2 -- vwsz1=_inc_vwsz1 
+    inc.z i
+    bne !+
+    inc.z i+1
+  !:
+    // [5] phi from main::@2 to main::@1 [phi:main::@2->main::@1]
+  __b1_from___b2:
+    // [5] phi (signed word) main::lasti#2 = (signed word) main::lasti#1 [phi:main::@2->main::@1#0] -- register_copy 
+    // [5] phi (signed word) main::i#2 = (signed word) main::i#1 [phi:main::@2->main::@1#1] -- register_copy 
+    jmp __b1
+}
+  // File Data
+
+REGISTER UPLIFT POTENTIAL REGISTERS
+Statement [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2 [ main::i#2 main::lasti#2 ] ( main:2 [ main::i#2 main::lasti#2 ] ) always clobbers reg byte a 
+Statement [8] (byte~) main::$1 ← < (signed word) main::lasti#2 [ main::i#2 main::$1 ] ( main:2 [ main::i#2 main::$1 ] ) always clobbers reg byte a 
+Statement [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2 [ main::i#2 main::$1 main::$2 ] ( main:2 [ main::i#2 main::$1 main::$2 ] ) always clobbers reg byte a 
+Removing always clobbered register reg byte a as potential for zp[1]:6 [ main::$1 ]
+Statement [10] *((byte*~) main::$2) ← (byte~) main::$1 [ main::i#2 ] ( main:2 [ main::i#2 ] ) always clobbers reg byte a reg byte y 
+Statement [11] (signed word) main::lasti#1 ← (signed word) main::i#2 [ main::i#2 main::lasti#1 ] ( main:2 [ main::i#2 main::lasti#1 ] ) always clobbers reg byte a 
+Statement [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2 [ main::i#2 main::lasti#2 ] ( main:2 [ main::i#2 main::lasti#2 ] ) always clobbers reg byte a 
+Statement [8] (byte~) main::$1 ← < (signed word) main::lasti#2 [ main::i#2 main::$1 ] ( main:2 [ main::i#2 main::$1 ] ) always clobbers reg byte a 
+Statement [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2 [ main::i#2 main::$1 main::$2 ] ( main:2 [ main::i#2 main::$1 main::$2 ] ) always clobbers reg byte a 
+Statement [10] *((byte*~) main::$2) ← (byte~) main::$1 [ main::i#2 ] ( main:2 [ main::i#2 ] ) always clobbers reg byte a reg byte y 
+Statement [11] (signed word) main::lasti#1 ← (signed word) main::i#2 [ main::i#2 main::lasti#1 ] ( main:2 [ main::i#2 main::lasti#1 ] ) always clobbers reg byte a 
+Potential registers zp[2]:2 [ main::i#2 main::i#1 ] : zp[2]:2 , 
+Potential registers zp[2]:4 [ main::lasti#2 main::lasti#1 ] : zp[2]:4 , 
+Potential registers zp[1]:6 [ main::$1 ] : zp[1]:6 , reg byte x , reg byte y , 
+Potential registers zp[2]:7 [ main::$2 ] : zp[2]:7 , 
+
+REGISTER UPLIFT SCOPES
+Uplift Scope [main] 31.17: zp[2]:2 [ main::i#2 main::i#1 ] 22: zp[2]:4 [ main::lasti#2 main::lasti#1 ] 22: zp[2]:7 [ main::$2 ] 11: zp[1]:6 [ main::$1 ] 
+Uplift Scope [] 
+
+Uplifting [main] best 1083 combination zp[2]:2 [ main::i#2 main::i#1 ] zp[2]:4 [ main::lasti#2 main::lasti#1 ] zp[2]:7 [ main::$2 ] reg byte x [ main::$1 ] 
+Uplifting [] best 1083 combination 
+Allocated (was zp[2]:7) zp[2]:6 [ main::$2 ]
+
+ASSEMBLER BEFORE OPTIMIZATION
+  // File Comments
+// https://gitlab.com/camelot/kickc/issues/336
+// ASM Static Register Value analysis erronously believes >-1 == 0
+  // Upstart
+.pc = $801 "Basic"
+:BasicUpstart(__bbegin)
+.pc = $80d "Program"
+  // Global Constants & labels
+  // @begin
+__bbegin:
+  // [1] phi from @begin to @1 [phi:@begin->@1]
+__b1_from___bbegin:
+  jmp __b1
+  // @1
+__b1:
+  // [2] call main 
+  // [4] phi from @1 to main [phi:@1->main]
+main_from___b1:
+  jsr main
+  // [3] phi from @1 to @end [phi:@1->@end]
+__bend_from___b1:
+  jmp __bend
+  // @end
+__bend:
+  // main
+main: {
+    .label screen = $400
+    .label lasti = 4
+    .label i = 2
+    .label __2 = 6
+    // [5] phi from main to main::@1 [phi:main->main::@1]
+  __b1_from_main:
+    // [5] phi (signed word) main::lasti#2 = (signed byte) -1 [phi:main->main::@1#0] -- vwsz1=vbsc1 
+    lda #<-1
+    sta.z lasti
+    lda #>-1
+    sta.z lasti+1
+    // [5] phi (signed word) main::i#2 = (signed byte) 0 [phi:main->main::@1#1] -- vwsz1=vbsc1 
+    lda #<0
+    sta.z i
+    lda #>0
+    sta.z i+1
+    jmp __b1
+    // main::@1
+  __b1:
+    // [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2 -- vwsz1_lt_vwuc1_then_la1 
+    lda.z i+1
+    bmi __b2
+    cmp #>$a
+    bcc __b2
+    bne !+
+    lda.z i
+    cmp #<$a
+    bcc __b2
+  !:
+    jmp __breturn
+    // main::@return
+  __breturn:
+    // [7] return 
+    rts
+    // main::@2
+  __b2:
+    // [8] (byte~) main::$1 ← < (signed word) main::lasti#2 -- vbuxx=_lo_vwsz1 
+    lda.z lasti
+    tax
+    // [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2 -- pbuz1=pbuc1_plus_vwsz2 
+    lda #<screen
+    clc
+    adc.z i
+    sta.z __2
+    lda #>screen
+    adc.z i+1
+    sta.z __2+1
+    // [10] *((byte*~) main::$2) ← (byte~) main::$1 -- _deref_pbuz1=vbuxx 
+    txa
+    ldy #0
+    sta (__2),y
+    // [11] (signed word) main::lasti#1 ← (signed word) main::i#2 -- vwsz1=vwsz2 
+    lda.z i
+    sta.z lasti
+    lda.z i+1
+    sta.z lasti+1
+    // [12] (signed word) main::i#1 ← ++ (signed word) main::i#2 -- vwsz1=_inc_vwsz1 
+    inc.z i
+    bne !+
+    inc.z i+1
+  !:
+    // [5] phi from main::@2 to main::@1 [phi:main::@2->main::@1]
+  __b1_from___b2:
+    // [5] phi (signed word) main::lasti#2 = (signed word) main::lasti#1 [phi:main::@2->main::@1#0] -- register_copy 
+    // [5] phi (signed word) main::i#2 = (signed word) main::i#1 [phi:main::@2->main::@1#1] -- register_copy 
+    jmp __b1
+}
+  // File Data
+
+ASSEMBLER OPTIMIZATIONS
+Removing instruction jmp __b1
+Removing instruction jmp __bend
+Removing instruction jmp __b1
+Removing instruction jmp __breturn
+Succesful ASM optimization Pass5NextJumpElimination
+Removing instruction lda #>-1
+Removing instruction lda #>0
+Succesful ASM optimization Pass5UnnecesaryLoadElimination
+Replacing label __bbegin with __b1
+Removing instruction __bbegin:
+Removing instruction __b1_from___bbegin:
+Removing instruction main_from___b1:
+Removing instruction __bend_from___b1:
+Succesful ASM optimization Pass5RedundantLabelElimination
+Removing instruction __bend:
+Removing instruction __b1_from_main:
+Removing instruction __breturn:
+Removing instruction __b1_from___b2:
+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()
+(byte~) main::$1 reg byte x 11.0
+(byte*~) main::$2 zp[2]:6 22.0
+(label) main::@1
+(label) main::@2
+(label) main::@return
+(signed word) main::i
+(signed word) main::i#1 i zp[2]:2 22.0
+(signed word) main::i#2 i zp[2]:2 9.166666666666666
+(signed word) main::lasti
+(signed word) main::lasti#1 lasti zp[2]:4 11.0
+(signed word) main::lasti#2 lasti zp[2]:4 11.0
+(const byte*) main::screen = (byte*) 1024
+
+zp[2]:2 [ main::i#2 main::i#1 ]
+zp[2]:4 [ main::lasti#2 main::lasti#1 ]
+reg byte x [ main::$1 ]
+zp[2]:6 [ main::$2 ]
+
+
+FINAL ASSEMBLER
+Score: 971
+
+  // File Comments
+// https://gitlab.com/camelot/kickc/issues/336
+// ASM Static Register Value analysis erronously believes >-1 == 0
+  // Upstart
+.pc = $801 "Basic"
+:BasicUpstart(main)
+.pc = $80d "Program"
+  // Global Constants & labels
+  // @begin
+  // [1] phi from @begin to @1 [phi:@begin->@1]
+  // @1
+  // [2] call main 
+  // [4] phi from @1 to main [phi:@1->main]
+  // [3] phi from @1 to @end [phi:@1->@end]
+  // @end
+  // main
+main: {
+    .label screen = $400
+    .label lasti = 4
+    .label i = 2
+    .label __2 = 6
+    // [5] phi from main to main::@1 [phi:main->main::@1]
+    // [5] phi (signed word) main::lasti#2 = (signed byte) -1 [phi:main->main::@1#0] -- vwsz1=vbsc1 
+    lda #<-1
+    sta.z lasti
+    sta.z lasti+1
+    // [5] phi (signed word) main::i#2 = (signed byte) 0 [phi:main->main::@1#1] -- vwsz1=vbsc1 
+    lda #<0
+    sta.z i
+    sta.z i+1
+    // main::@1
+  __b1:
+    // for(int i=0;i<10;i++)
+    // [6] if((signed word) main::i#2<(signed byte) $a) goto main::@2 -- vwsz1_lt_vwuc1_then_la1 
+    lda.z i+1
+    bmi __b2
+    cmp #>$a
+    bcc __b2
+    bne !+
+    lda.z i
+    cmp #<$a
+    bcc __b2
+  !:
+    // main::@return
+    // }
+    // [7] return 
+    rts
+    // main::@2
+  __b2:
+    // <lasti
+    // [8] (byte~) main::$1 ← < (signed word) main::lasti#2 -- vbuxx=_lo_vwsz1 
+    lda.z lasti
+    tax
+    // screen[i] = <lasti
+    // [9] (byte*~) main::$2 ← (const byte*) main::screen + (signed word) main::i#2 -- pbuz1=pbuc1_plus_vwsz2 
+    lda #<screen
+    clc
+    adc.z i
+    sta.z __2
+    lda #>screen
+    adc.z i+1
+    sta.z __2+1
+    // [10] *((byte*~) main::$2) ← (byte~) main::$1 -- _deref_pbuz1=vbuxx 
+    txa
+    ldy #0
+    sta (__2),y
+    // lasti = i
+    // [11] (signed word) main::lasti#1 ← (signed word) main::i#2 -- vwsz1=vwsz2 
+    lda.z i
+    sta.z lasti
+    lda.z i+1
+    sta.z lasti+1
+    // for(int i=0;i<10;i++)
+    // [12] (signed word) main::i#1 ← ++ (signed word) main::i#2 -- vwsz1=_inc_vwsz1 
+    inc.z i
+    bne !+
+    inc.z i+1
+  !:
+    // [5] phi from main::@2 to main::@1 [phi:main::@2->main::@1]
+    // [5] phi (signed word) main::lasti#2 = (signed word) main::lasti#1 [phi:main::@2->main::@1#0] -- register_copy 
+    // [5] phi (signed word) main::i#2 = (signed word) main::i#1 [phi:main::@2->main::@1#1] -- register_copy 
+    jmp __b1
+}
+  // File Data
+
--- a/src/test/ref/static-register-optimization-problem.sym
+++ b/src/test/ref/static-register-optimization-problem.sym
@ -0,0 +1,21 @@
+(label) @1
+(label) @begin
+(label) @end
+(void()) main()
+(byte~) main::$1 reg byte x 11.0
+(byte*~) main::$2 zp[2]:6 22.0
+(label) main::@1
+(label) main::@2
+(label) main::@return
+(signed word) main::i
+(signed word) main::i#1 i zp[2]:2 22.0
+(signed word) main::i#2 i zp[2]:2 9.166666666666666
+(signed word) main::lasti
+(signed word) main::lasti#1 lasti zp[2]:4 11.0
+(signed word) main::lasti#2 lasti zp[2]:4 11.0
+(const byte*) main::screen = (byte*) 1024
+
+zp[2]:2 [ main::i#2 main::i#1 ]
+zp[2]:4 [ main::lasti#2 main::lasti#1 ]
+reg byte x [ main::$1 ]
+zp[2]:6 [ main::$2 ]