From 70ed2b4203f54ac7f21b064a0b097b74979fe4be Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sat, 22 Jul 2023 23:08:22 +0200
Subject: [PATCH] fix compilation of large bitshifts

---
 .../cpu6502/assignment/AssignmentAsmGen.kt    |  5 +--
 .../optimizer/ConstantFoldingOptimizer.kt     | 41 +++++++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
index 9e21cbcb2..acbf6d728 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
@@ -590,7 +590,6 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
                 when (shifts) {
                     in 0..7 -> {
-                        require(dt==DataType.UBYTE)
                         if (expr.operator == "<<") {
                             repeat(shifts) {
                                 asmgen.out("  asl  a")
@@ -609,7 +608,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     }
                     else -> {
                         if(signed && expr.operator==">>") {
-                            TODO("signed byte >> overshift should have been compiled away?")
+                            asmgen.out("  ldy  #$shifts |  jsr  math.lsr_byte_A")
                         } else {
                             asmgen.out("  lda  #0")
                         }
@@ -660,7 +659,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     }
                     else -> {
                         if(signed && expr.operator==">>") {
-                            TODO("signed word >> overshift should have been compiled away?")
+                            asmgen.out("  ldx  #$shifts |  jsr  math.lsr_word_AY")
                         } else {
                             asmgen.out("  lda  #0 |  ldy  #0")
                         }
diff --git a/codeOptimizers/src/prog8/optimizer/ConstantFoldingOptimizer.kt b/codeOptimizers/src/prog8/optimizer/ConstantFoldingOptimizer.kt
index 033e5065b..b4a36aa8c 100644
--- a/codeOptimizers/src/prog8/optimizer/ConstantFoldingOptimizer.kt
+++ b/codeOptimizers/src/prog8/optimizer/ConstantFoldingOptimizer.kt
@@ -235,6 +235,47 @@ class ConstantFoldingOptimizer(private val program: Program) : AstWalker() {
             }
         }
 
+        if(rightconst!=null && (expr.operator=="<<" || expr.operator==">>")) {
+            val dt = expr.left.inferType(program)
+            if(dt.isBytes && rightconst.number>=8) {
+                if(dt.istype(DataType.UBYTE)) {
+                    val zeroUB = NumericLiteral(DataType.UBYTE, 0.0, expr.position)
+                    modifications.add(IAstModification.ReplaceNode(expr, zeroUB, parent))
+                } else {
+                    if(leftconst!=null) {
+                        val zeroB = NumericLiteral(DataType.BYTE, 0.0, expr.position)
+                        val minusoneB = NumericLiteral(DataType.BYTE, -1.0, expr.position)
+                        if(leftconst.number<0.0) {
+                            if(expr.operator=="<<")
+                                modifications.add(IAstModification.ReplaceNode(expr, zeroB, parent))
+                            else
+                                modifications.add(IAstModification.ReplaceNode(expr, minusoneB, parent))
+                        } else {
+                            modifications.add(IAstModification.ReplaceNode(expr, zeroB, parent))
+                        }
+                    }
+                }
+            }
+            else if(dt.isWords && rightconst.number>=16) {
+                if(dt.istype(DataType.UWORD)) {
+                    val zeroUW = NumericLiteral(DataType.UWORD, 0.0, expr.position)
+                    modifications.add(IAstModification.ReplaceNode(expr, zeroUW, parent))
+                } else {
+                    if(leftconst!=null) {
+                        val zeroW = NumericLiteral(DataType.WORD, 0.0, expr.position)
+                        val minusoneW = NumericLiteral(DataType.WORD, -1.0, expr.position)
+                        if(leftconst.number<0.0) {
+                            if(expr.operator=="<<")
+                                modifications.add(IAstModification.ReplaceNode(expr, zeroW, parent))
+                            else
+                                modifications.add(IAstModification.ReplaceNode(expr, minusoneW, parent))
+                        } else {
+                            modifications.add(IAstModification.ReplaceNode(expr, zeroW, parent))
+                        }
+                    }
+                }
+            }
+        }
 
         return modifications
     }