fix IR if expression sometimes lacking a cmpi after calculation of the condition value

VM/IR: add a returni immediate value return instruction to replace certain returnr's

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

@@ -1395,12 +1395,14 @@ class IRCodeGen(
     private fun ifWithElse_IntegerCond(ifElse: PtIfElse): List<IRCodeChunkBase> {
         val result = mutableListOf<IRCodeChunkBase>()
 
-        fun translateSimple(condition: PtExpression, jumpFalseOpcode: Opcode) {
+        fun translateSimple(condition: PtExpression, jumpFalseOpcode: Opcode, addCmpiZero: Boolean) {
 
             if(condition is PtBuiltinFunctionCall && condition.name.startsWith("prog8_ifelse_bittest_"))
                 throw AssemblyError("IR codegen doesn't have special instructions for dedicated BIT tests and should just still use normal AND")
 
             val tr = expressionEval.translateExpression(condition)
+            if(addCmpiZero)
+                tr.chunks.last().instructions.add(IRInstruction(Opcode.CMPI, tr.dt, reg1 = tr.resultReg, immediate = 0))
             result += tr.chunks
             if(ifElse.hasElse()) {
                 val elseLabel = createLabelName()
@@ -1420,7 +1422,7 @@ class IRCodeGen(
 
         fun translateBinExpr(condition: PtBinaryExpression) {
             if(condition.operator in LogicalOperators)
-                return translateSimple(condition, Opcode.BSTEQ)
+                return translateSimple(condition, Opcode.BSTEQ, false)
 
             val signed = condition.left.type in SignedDatatypes
             val elseBranchFirstReg: Int
@@ -1559,18 +1561,21 @@ class IRCodeGen(
         when(val cond=ifElse.condition) {
             is PtBool -> {
                 // normally this will be optimized away, but not with -noopt
-                translateSimple(cond, Opcode.BSTEQ)
+                translateSimple(cond, Opcode.BSTEQ, false)
             }
             is PtTypeCast -> {
                 require(cond.type==DataType.BOOL && cond.value.type in NumericDatatypes)
-                translateSimple(cond, Opcode.BSTEQ)
+                translateSimple(cond, Opcode.BSTEQ, false)
             }
-            is PtIdentifier, is PtArrayIndexer, is PtBuiltinFunctionCall, is PtFunctionCall, is PtContainmentCheck -> {
+            is PtIdentifier, is PtArrayIndexer, is PtContainmentCheck -> {
-                translateSimple(cond, Opcode.BSTEQ)
+                translateSimple(cond, Opcode.BSTEQ, false)
+            }
+            is PtBuiltinFunctionCall, is PtFunctionCall -> {
+                translateSimple(cond, Opcode.BSTEQ, true)
             }
             is PtPrefix -> {
                 require(cond.operator=="not")
-                translateSimple(cond.value, Opcode.BSTNE)
+                translateSimple(cond.value, Opcode.BSTNE, false)
             }
             is PtBinaryExpression -> {
                 translateBinExpr(cond)
@@ -1648,14 +1653,22 @@ class IRCodeGen(
             addInstr(result, IRInstruction(Opcode.RETURN), null)
         } else {
             if(value.type==DataType.FLOAT) {
+                if(value is PtNumber) {
+                    addInstr(result, IRInstruction(Opcode.RETURNI, IRDataType.FLOAT, immediateFp = value.number), null)
+                } else {
                     val tr = expressionEval.translateExpression(value)
                     addToResult(result, tr, -1, tr.resultFpReg)
                     addInstr(result, IRInstruction(Opcode.RETURNR, IRDataType.FLOAT, fpReg1 = tr.resultFpReg), null)
                 }
+            }
             else {
+                if(value.asConstInteger()!=null) {
+                    addInstr(result, IRInstruction(Opcode.RETURNI, irType(value.type), immediate = value.asConstInteger()), null)
+                } else {
                     val tr = expressionEval.translateExpression(value)
                     addToResult(result, tr, tr.resultReg, -1)
-                addInstr(result, IRInstruction(Opcode.RETURNR, irType(value.type) , reg1=tr.resultReg), null)
+                    addInstr(result, IRInstruction(Opcode.RETURNR, irType(value.type), reg1 = tr.resultReg), null)
+                }
             }
         }
         return result

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

@@ -299,7 +299,7 @@ class IRPeepholeOptimizer(private val irprog: IRProgram) {
             }
 
             // remove useless RETURN
-            if(idx>0 && (ins.opcode == Opcode.RETURN || ins.opcode==Opcode.RETURNR)) {
+            if(idx>0 && (ins.opcode == Opcode.RETURN || ins.opcode==Opcode.RETURNR || ins.opcode==Opcode.RETURNI)) {
                 val previous = chunk.instructions[idx-1]
                 if(previous.opcode in OpcodesThatJump) {
                     chunk.instructions.removeAt(idx)

docs/source/todo.rst

@@ -1,9 +1,8 @@
 TODO
 ====
 
-VM/IR: fix return value passing from %ir routines?  (diskio.exists routine always returns true)
+replace zsound example by a zsmkit example
-
+contribute a short how-to to the zsmkit repo for building a suitable blob
-make better zsmkit example
 write a howto for integrating third party library code like zsmkit and vtui
 
 Improve register load order in subroutine call args assignments:

examples/test.p8

@@ -1,30 +1,60 @@
-%import diskio
 %import textio
-;%import gfx_hires4
+%import diskio
 %option no_sysinit
 %zeropage basicsafe
 
 main {
 
     sub start() {
-        txt.print_bool(diskio.exists("doesntexist.prg"))
+        txt.print_ub(exists_byte("test.prg"))
+        txt.spc()
+        txt.print_ub(exists_byte("doesntexist.xxx"))
         txt.nl()
-        txt.print_bool(diskio.exists("test.prg"))
+        txt.print_bool(exists_bool("test.prg"))
+        txt.spc()
+        txt.print_bool(exists_bool("doesntexist.xxx"))
         txt.nl()
+        txt.print_bool(exists1("test.prg"))
+        txt.spc()
+        txt.print_bool(exists1("doesntexist.xxx"))
+        txt.nl()
+        txt.print_bool(exists2("test.prg"))
+        txt.spc()
+        txt.print_bool(exists2("doesntexist.xxx"))
+        txt.nl()
+    }
 
-        diskio.f_open_w("dump.bin")
+    sub exists1(str filename) -> bool {
-        diskio.f_close_w()
+        ; -- returns true if the given file exists on the disk, otherwise false
-        diskio.f_close_w()
+        if exists_byte(filename)!=0 {
-        diskio.f_close_w()
+            return true
-        diskio.f_close_w()
+        }
+        return false
+    }
 
-;        gfx_hires4.graphics_mode()
+    sub exists2(str filename) -> bool {
-;        gfx_hires4.circle(300, 250, 200, 3)
+        ; -- returns true if the given file exists on the disk, otherwise false
-;        gfx_hires4.rect(320, 10, 20, 200, 3)
+        if exists_bool(filename) {
-;        gfx_hires4.fill(310, 310, 2)
+            return true
-;
+        }
-;        repeat {
+        return false
-;        }
+    }
+
+
+    sub exists_bool(str name) -> bool {
+        %ir {{
+            loadm.w r65535,main.exists_bool.name
+            syscall 52 (r65535.w): r0.b
+            returnr.b r0
+        }}
+    }
+
+    sub exists_byte(str name) -> ubyte {
+        %ir {{
+            loadm.w r65535,main.exists_byte.name
+            syscall 52 (r65535.w): r0.b
+            returnr.b r0
+        }}
     }
 }
 

intermediate/src/prog8/intermediate/IRInstructions.kt

@@ -82,6 +82,7 @@ syscall   number (argument register list) [: resultreg.type]
                                         Always preceded by parameter setup and preparecall instructions
 return                                - restore last saved instruction location and continue at that instruction. No return value.
 returnr     reg1                      - like return, but also returns the value in reg1 to the caller
+returni            number             - like return, but also returns the immediate value to the caller
 
 
 
@@ -289,6 +290,7 @@ enum class Opcode {
     SYSCALL,
     RETURN,
     RETURNR,
+    RETURNI,
 
     BSTCC,
     BSTCS,
@@ -428,7 +430,8 @@ val OpcodesThatJump = arrayOf(
     Opcode.JUMP,
     Opcode.JUMPI,
     Opcode.RETURN,
-    Opcode.RETURNR
+    Opcode.RETURNR,
+    Opcode.RETURNI
 )
 
 val OpcodesThatBranch = arrayOf(
@@ -436,6 +439,7 @@ val OpcodesThatBranch = arrayOf(
     Opcode.JUMPI,
     Opcode.RETURN,
     Opcode.RETURNR,
+    Opcode.RETURNI,
     Opcode.CALLI,
     Opcode.CALL,
     Opcode.SYSCALL,
@@ -647,7 +651,8 @@ val instructionFormats = mutableMapOf(
     Opcode.CALL       to InstructionFormat.from("N,call"),
     Opcode.SYSCALL    to InstructionFormat.from("N,syscall"),
     Opcode.RETURN     to InstructionFormat.from("N"),
-    Opcode.RETURNR    to InstructionFormat.from("BW,>r1        | F,>fr1"),
+    Opcode.RETURNR    to InstructionFormat.from("BW,<r1        | F,<fr1"),
+    Opcode.RETURNI    to InstructionFormat.from("BW,<i         | F,<i"),
     Opcode.BSTCC      to InstructionFormat.from("N,<a"),
     Opcode.BSTCS      to InstructionFormat.from("N,<a"),
     Opcode.BSTEQ      to InstructionFormat.from("N,<a"),

intermediate/src/prog8/intermediate/IRProgram.kt

@@ -145,7 +145,7 @@ class IRProgram(val name: String,
 
             // link all jump and branching instructions to their target
             chunk.instructions.forEach {
-                if(it.opcode in OpcodesThatBranch && it.opcode!=Opcode.JUMPI && it.opcode!=Opcode.RETURN && it.opcode!=Opcode.RETURNR && it.labelSymbol!=null) {
+                if(it.opcode in OpcodesThatBranch && it.opcode!=Opcode.JUMPI && it.opcode!=Opcode.RETURN && it.opcode!=Opcode.RETURNR && it.opcode!=Opcode.RETURNI && it.labelSymbol!=null) {
                     if(it.labelSymbol.startsWith('$') || it.labelSymbol.first().isDigit()) {
                         // it's a call to an address (romsub most likely)
                         requireNotNull(it.address)

virtualmachine/src/prog8/vm/VirtualMachine.kt

@@ -213,6 +213,7 @@ class VirtualMachine(irProgram: IRProgram) {
             Opcode.SYSCALL -> InsSYSCALL(ins)
             Opcode.RETURN -> InsRETURN()
             Opcode.RETURNR -> InsRETURNR(ins)
+            Opcode.RETURNI -> InsRETURNI(ins)
             Opcode.BSTCC -> InsBSTCC(ins)
             Opcode.BSTCS -> InsBSTCS(ins)
             Opcode.BSTEQ -> InsBSTEQ(ins)
@@ -656,6 +657,46 @@ class VirtualMachine(irProgram: IRProgram) {
         }
     }
 
+    private fun InsRETURNI(i: IRInstruction) {
+        if(callStack.isEmpty())
+            exit(0)
+        else {
+            val context = callStack.removeLast()
+            val returns = context.fcallSpec.returns
+            when (i.type!!) {
+                IRDataType.BYTE -> {
+                    if(returns.isNotEmpty())
+                        registers.setUB(returns.single().registerNum, i.immediate!!.toUByte())
+                    else {
+                        val callInstr = context.returnChunk.instructions[context.returnIndex-1]
+                        if(callInstr.opcode!=Opcode.CALL)
+                            throw IllegalArgumentException("missing return value reg")
+                    }
+                }
+                IRDataType.WORD -> {
+                    if(returns.isNotEmpty())
+                        registers.setUW(returns.single().registerNum, i.immediate!!.toUShort())
+                    else {
+                        val callInstr = context.returnChunk.instructions[context.returnIndex-1]
+                        if(callInstr.opcode!=Opcode.CALL)
+                            throw IllegalArgumentException("missing return value reg")
+                    }
+                }
+                IRDataType.FLOAT -> {
+                    if(returns.isNotEmpty())
+                        registers.setFloat(returns.single().registerNum, i.immediateFp!!)
+                    else {
+                        val callInstr = context.returnChunk.instructions[context.returnIndex-1]
+                        if(callInstr.opcode!=Opcode.CALL)
+                            throw IllegalArgumentException("missing return value reg")
+                    }
+                }
+            }
+            pcChunk = context.returnChunk
+            pcIndex = context.returnIndex
+        }
+    }
+
     private fun InsRETURNR(i: IRInstruction) {
         if(callStack.isEmpty())
             exit(0)