IR: fix forloop codegen for steps != 1

codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt

@@ -552,22 +552,24 @@ class IRCodeGen(
 
         addInstr(result, IRInstruction(Opcode.STOREM, loopvarDtIr, reg1=fromTr.resultReg, labelSymbol=loopvarSymbol), null)
         result += labelFirstChunk(translateNode(forLoop.statements), loopLabel)
-        result += addConstMem(loopvarDtIr, null, loopvarSymbol, step)
         addInstr(result, IRInstruction(Opcode.LOADM, loopvarDtIr, reg1 = fromTr.resultReg, labelSymbol = loopvarSymbol), null)
-        // if endvalue >= index, iterate loop
-        val branchInstr = if(loopvarDt in SignedDatatypes) {
-            if(step>0)
-                IRInstruction(Opcode.BGESR, loopvarDtIr, reg1=toTr.resultReg, reg2=fromTr.resultReg, labelSymbol=loopLabel)
-            else
-                IRInstruction(Opcode.BGESR, loopvarDtIr, reg1=fromTr.resultReg, reg2=toTr.resultReg, labelSymbol=loopLabel)
+        if(step==1 || step==-1) {
+            // if endvalue == index, stop loop, else iterate
+            addInstr(result, IRInstruction(Opcode.BEQR, loopvarDtIr, reg1=toTr.resultReg, reg2=fromTr.resultReg, labelSymbol = labelAfterFor), null)
+            result += addConstMem(loopvarDtIr, null, loopvarSymbol, step)
+            addInstr(result, IRInstruction(Opcode.JUMP, labelSymbol = loopLabel), null)
         } else {
-            if(step>0)
-                IRInstruction(Opcode.BGER, loopvarDtIr, reg1=toTr.resultReg, reg2=fromTr.resultReg, labelSymbol=loopLabel)
+            // ind/dec index, then:
+            // ascending: if endvalue >= index, iterate
+            // descending: if index >= endvalue, iterate
+            result += addConstMem(loopvarDtIr, null, loopvarSymbol, step)
+            addInstr(result, IRInstruction(Opcode.LOADM, loopvarDtIr, reg1=fromTr.resultReg, labelSymbol = loopvarSymbol), null)
+            if(step > 0)
+                addInstr(result, IRInstruction(Opcode.CMP, loopvarDtIr, reg1 = toTr.resultReg, fromTr.resultReg), null)
             else
-                IRInstruction(Opcode.BGER, loopvarDtIr, reg1=fromTr.resultReg, reg2=toTr.resultReg, labelSymbol=loopLabel)
+                addInstr(result, IRInstruction(Opcode.CMP, loopvarDtIr, reg1 = fromTr.resultReg, toTr.resultReg), null)
+            addInstr(result, IRInstruction(Opcode.BSTPOS, labelSymbol = loopLabel), null)
         }
-        addInstr(result, branchInstr, null)
-
         result += IRCodeChunk(labelAfterFor, null)
         return result
     }

docs/source/syntaxreference.rst

@@ -145,12 +145,16 @@ Directives
 
     Level: not at module scope.
     This directive can only be used inside a block.
-    The assembler will include the file as binary bytes at this point, prog8 will not process this at all.
-    The optional offset and length can be used to select a particular piece of the file.
+    The assembler itself will include the file as binary bytes at this point, prog8 will not process this at all.
+    This means that the filename must be spelled exactly as it appears on your computer's file system.
+    Note that this filename may differ in case compared to when you chose to load the file from disk from within the
+    program code itself (for example on the C64 and X16 there's the PETSCII encoding difference).
     The file is located relative to the current working directory!
+    The optional offset and length can be used to select a particular piece of the file.
     To reference the contents of the included binary data, you can put a label in your prog8 code
     just before the %asmbinary. An example program for this can be found below at the description of %asminclude.
 
+
 .. data:: %asminclude "<filename>"
 
     Level: not at module scope.

docs/source/todo.rst

@@ -1,9 +1,13 @@
 TODO
 ====
 
-- VM: fix endless loop  n=0 :: for i in 5 downto n  (fine for n=1)  (wrong for bytes and words)
+- codegen: fix endless loop uword n=0 :: for uword i in 10 downto n step -3
+
+- investigate if the hiscores issue on the forum is a compiler bug or not.
 
 - IR: instructions that do type conversion (SZ etc, CONCAT, SGN) should put the result in a DIFFERENT register.
+- IR: optimize forloop codegen to use a reg as loop variable instead of a memory variable, just store it in the mem var before entering the loop body
+      check repeat loop as well it shouldn't be using a tempvar just a register to count.
 
 ...
 

examples/test.p8

@@ -4,23 +4,31 @@
 
 main {
     sub start() {
-        byte intensity = -25
-        txt.print_b(intensity)
-        txt.nl()
-        txt.print_b(abs(intensity))
-        intensity = abs(intensity)
-        txt.nl()
-        txt.print_b(intensity)
-        txt.nl()
+        uword  n=0
+        uword i
+        txt.print("ascending:\n")
+        n=10
+        for i in 0 to n step 3 {
+            cx16.r0++
+            txt.print(" i=")
+            txt.print_uw(i)
+            txt.spc()
+            txt.print(" n=")
+            txt.print_uw(n)
+            txt.nl()
+        }
 
-        txt.print_uw0(12345)
-        txt.nl()
-        word intensityw = -12345
-        txt.print_w(intensityw)
-        txt.nl()
-        txt.print_w(abs(intensityw))
-        intensityw = abs(intensityw)
-        txt.nl()
-        txt.print_w(intensityw)
+        txt.print("descending:\n")
+        n=0
+        for i in 10 downto n step -3 {
+            cx16.r0++
+            txt.print(" i=")
+            txt.print_uw(i)
+            txt.spc()
+            txt.print(" n=")
+            txt.print_uw(n)
+            txt.nl()
+        }
     }
 }
+