From 16454f55608210af947760d95ec21546247aa3f9 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Tue, 9 Jul 2019 21:59:50 +0200
Subject: [PATCH] optimized when asm

---
 .../prog8/compiler/target/c64/AsmOptimizer.kt | 33 ++++++++++++++++++-
 .../prog8/compiler/target/c64/AsmPatterns.kt  |  2 +-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/compiler/src/prog8/compiler/target/c64/AsmOptimizer.kt b/compiler/src/prog8/compiler/target/c64/AsmOptimizer.kt
index 3fd563aa9..df91b04c0 100644
--- a/compiler/src/prog8/compiler/target/c64/AsmOptimizer.kt
+++ b/compiler/src/prog8/compiler/target/c64/AsmOptimizer.kt
@@ -32,6 +32,15 @@ fun optimizeAssembly(lines: MutableList<String>): Int {
     if(removeLines.isNotEmpty()) {
         for (i in removeLines.reversed())
             lines.removeAt(i)
+        linesByFour = getLinesBy(lines, 4)
+        numberOfOptimizations++
+    }
+
+    removeLines = optimizeCmpSequence(linesByFour)
+    if(removeLines.isNotEmpty()) {
+        for (i in removeLines.reversed())
+            lines.removeAt(i)
+        linesByFour = getLinesBy(lines, 4)
         numberOfOptimizations++
     }
 
@@ -40,6 +49,7 @@ fun optimizeAssembly(lines: MutableList<String>): Int {
     if(removeLines.isNotEmpty()) {
         for (i in removeLines.reversed())
             lines.removeAt(i)
+        linesByFourteen = getLinesBy(lines, 14)
         numberOfOptimizations++
     }
 
@@ -48,6 +58,27 @@ fun optimizeAssembly(lines: MutableList<String>): Int {
     return numberOfOptimizations
 }
 
+fun optimizeCmpSequence(linesByFour: List<List<IndexedValue<String>>>): List<Int> {
+    // the when statement (on bytes) generates a sequence of:
+    //	 lda $ce01,x
+    //	 cmp #$20
+    //	 beq  check_prog8_s72choice_32
+    //	 lda $ce01,x
+    //	 cmp #$21
+    //	 beq  check_prog8_s73choice_33
+    // the repeated lda can be removed
+    val removeLines = mutableListOf<Int>()
+    for(lines in linesByFour) {
+        if(lines[0].value.trim()=="lda  ${(ESTACK_LO+1).toHex()},x" &&
+                lines[1].value.trim().startsWith("cmp ") &&
+                lines[2].value.trim().startsWith("beq ") &&
+                lines[3].value.trim()=="lda  ${(ESTACK_LO+1).toHex()},x") {
+            removeLines.add(lines[3].index) // remove the second lda
+        }
+    }
+    return removeLines
+}
+
 fun optimizeUselessStackByteWrites(linesByFour: List<List<IndexedValue<String>>>): List<Int> {
     // sta on stack, dex, inx, lda from stack -> eliminate this useless stack byte write
     // this is a lot harder for word values because the instruction sequence varies.
@@ -132,7 +163,7 @@ fun optimizeSameAssignments(linesByFourteen: List<List<IndexedValue<String>>>):
 }
 
 private fun getLinesBy(lines: MutableList<String>, windowSize: Int) =
-// all lines (that aren't empty or comments) in sliding pairs of 2
+// all lines (that aren't empty or comments) in sliding windows of certain size
         lines.withIndex().filter { it.value.isNotBlank() && !it.value.trimStart().startsWith(';') }.windowed(windowSize, partialWindows = false)
 
 private fun optimizeStoreLoadSame(linesByFour: List<List<IndexedValue<String>>>): List<Int> {
diff --git a/compiler/src/prog8/compiler/target/c64/AsmPatterns.kt b/compiler/src/prog8/compiler/target/c64/AsmPatterns.kt
index 2c1634138..de6a1b801 100644
--- a/compiler/src/prog8/compiler/target/c64/AsmPatterns.kt
+++ b/compiler/src/prog8/compiler/target/c64/AsmPatterns.kt
@@ -2309,7 +2309,7 @@ internal val patterns = listOf<AsmPattern>(
         },
         AsmPattern(listOf(Opcode.DUP_B, Opcode.CMP_UB),
                 listOf(Opcode.DUP_B, Opcode.CMP_B)) { segment ->
-            """ lda ${(ESTACK_LO+1).toHex()},x | cmp #${segment[1].arg!!.integerValue().toHex()} """
+            """ lda  ${(ESTACK_LO+1).toHex()},x | cmp  #${segment[1].arg!!.integerValue().toHex()} """
         }
 
 )