translate address-of into + expression for non-const address ptrs too,

also IR optimization to use immediate arithmetic opcodes if possible

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

@@ -440,6 +440,52 @@ jump p8_label_gen_2
                 }
                 else -> {}
             }
+
+            fun optimizeImmediateLoadAssociative(replacementOpcode: Opcode) {
+
+                fun getImmediateLoad(reg: Int): Pair<Int, Int>? {
+                    // look if the given register gets an immediate value 1 or 2 istructions back
+                    // returns (index of load instruction, immediate value) or null.
+                    if(idx>=1) {
+                        val previous = indexedInstructions[idx-1].value
+                        if(previous.opcode==Opcode.LOAD && previous.reg1==reg)
+                            return idx-1 to previous.immediate!!
+                    }
+                    if(idx>=2) {
+                        val previous = indexedInstructions[idx-2].value
+                        if(previous.opcode==Opcode.LOAD && previous.reg1==reg)
+                            return idx-2 to previous.immediate!!
+                    }
+                    return null
+                }
+
+                val immediate1 = getImmediateLoad(ins.reg1!!)
+                if(immediate1!=null) {
+                    chunk.instructions[idx] = IRInstruction(replacementOpcode, ins.type, reg1 = ins.reg2, immediate = immediate1.second)
+                    chunk.instructions.removeAt(immediate1.first)
+                    changed=true
+                } else {
+                    val immediate2 = getImmediateLoad(ins.reg2!!)
+                    if (immediate2 != null) {
+                        chunk.instructions[idx] = IRInstruction(replacementOpcode, ins.type, reg1 = ins.reg1, immediate = immediate2.second)
+                        chunk.instructions.removeAt(immediate2.first)
+                        changed=true
+                    }
+                }
+            }
+
+            // try to use immediate arithmetic instruction if possible
+            when(ins.opcode) {
+                Opcode.ADDR -> optimizeImmediateLoadAssociative(Opcode.ADD)
+                Opcode.MULR -> optimizeImmediateLoadAssociative(Opcode.MUL)
+                Opcode.MULSR -> optimizeImmediateLoadAssociative(Opcode.MULS)
+//                Opcode.SUBR -> TODO("ir peephole Subr")
+//                Opcode.DIVR -> TODO("ir peephole Divr")
+//                Opcode.DIVSR -> TODO("ir peephole Divsr")
+//                Opcode.MODR -> TODO("ir peephole Modr")
+//                Opcode.DIVMODR -> TODO("ir peephole DivModr")
+                else -> {}
+            }
         }
         return changed
     }

compiler/src/prog8/compiler/astprocessing/VariousCleanups.kt

@@ -480,18 +480,31 @@ internal class VariousCleanups(val program: Program, val errors: IErrorReporter,
 
     override fun after(addressOf: AddressOf, parent: Node): Iterable<IAstModification> {
         if(addressOf.arrayIndex!=null) {
-            val tgt = addressOf.identifier?.constValue(program)
-            if (tgt != null && tgt.type.isInteger) {
-                // &constant[idx]  -->  constant + idx
-                val indexExpr = addressOf.arrayIndex!!.indexExpr
-                val right = if(indexExpr.inferType(program) issimpletype tgt.type)
-                    indexExpr
-                else
-                    TypecastExpression(indexExpr, DataType.forDt(tgt.type), true, indexExpr.position)
-                val add = BinaryExpression(tgt, "+", right, addressOf.position)
-                return listOf(
-                    IAstModification.ReplaceNode(addressOf, add, parent)
-                )
+            val tgt = addressOf.identifier
+            if(tgt!=null) {
+                val constAddress = tgt.constValue(program)
+                if (constAddress != null && constAddress.type.isInteger) {
+                    // &constant[idx]  -->  constant + idx
+                    val indexExpr = addressOf.arrayIndex!!.indexExpr
+                    val right = if (indexExpr.inferType(program) issimpletype constAddress.type)
+                        indexExpr
+                    else
+                        TypecastExpression(indexExpr, DataType.forDt(constAddress.type), true, indexExpr.position)
+                    val add = BinaryExpression(constAddress, "+", right, addressOf.position)
+                    return listOf(IAstModification.ReplaceNode(addressOf, add, parent))
+                } else {
+                    val decl = tgt.targetVarDecl()!!
+                    if(decl.datatype.isInteger) {
+                        // &addressvar[idx]  -->  addressvar + idx
+                        val indexExpr = addressOf.arrayIndex!!.indexExpr
+                        val right = if (indexExpr.inferType(program) istype decl.datatype)
+                            indexExpr
+                        else
+                            TypecastExpression(indexExpr, decl.datatype, true, indexExpr.position)
+                        val add = BinaryExpression(tgt, "+", right, addressOf.position)
+                        return listOf(IAstModification.ReplaceNode(addressOf, add, parent))
+                    }
+                }
             }
         }
         return noModifications

docs/source/todo.rst

@@ -88,7 +88,7 @@ IR/VM
 - implement fast code paths for TODO("inplace split....
 - implement more TODOs in AssignmentGen
 - do something with the 'split' tag on split word arrays
-- add more optimizations in IRPeepholeOptimizer
+- add more optimizations in IRPeepholeOptimizer, implement the TODOs in there at least
 - idea: replace all scalar variables that are not @shared by an allocated register. Keep a table of the variable to register mapping (including the datatype)
   global initialization values are simply a list of LOAD instructions.
   Variables replaced include all subroutine parameters? Or not?  So the only variables that remain as variables are arrays and strings.