From 8be234973ca7d93a78ba20d398dc6e865a1239c9 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sat, 21 Nov 2020 19:09:02 +0100
Subject: [PATCH] rollback failed optimization of memory expressions (code size
 got too large)

---
 compiler/res/prog8lib/prog8_lib.asm           | 26 +++++++++++++++++++
 .../assignment/AugmentableAssignmentAsmGen.kt | 22 ++++------------
 examples/charset.p8                           |  1 -
 3 files changed, 31 insertions(+), 18 deletions(-)

diff --git a/compiler/res/prog8lib/prog8_lib.asm b/compiler/res/prog8lib/prog8_lib.asm
index c2ba2fb11..a4493536e 100644
--- a/compiler/res/prog8lib/prog8_lib.asm
+++ b/compiler/res/prog8lib/prog8_lib.asm
@@ -5,6 +5,32 @@
 ;
 ; indent format: TABS, size=8
 
+
+read_byte_from_address_on_stack	.proc
+	; -- read the byte from the memory address on the top of the stack, return in A (stack remains unchanged)
+		lda  P8ESTACK_LO+1,x
+		ldy  P8ESTACK_HI+1,x
+		sta  P8ZP_SCRATCH_W2
+		sty  P8ZP_SCRATCH_W2+1
+		ldy  #0
+		lda  (P8ZP_SCRATCH_W2),y
+		rts
+		.pend
+
+
+write_byte_to_address_on_stack	.proc
+	; -- write the byte in A to the memory address on the top of the stack (stack remains unchanged)
+		ldy  P8ESTACK_LO+1,x
+		sty  P8ZP_SCRATCH_W2
+		ldy  P8ESTACK_HI+1,x
+		sty  P8ZP_SCRATCH_W2+1
+		ldy  #0
+		sta  (P8ZP_SCRATCH_W2),y
+		rts
+		.pend
+
+
+
 neg_b		.proc
 		lda  #0
 		sec
diff --git a/compiler/src/prog8/compiler/target/c64/codegen/assignment/AugmentableAssignmentAsmGen.kt b/compiler/src/prog8/compiler/target/c64/codegen/assignment/AugmentableAssignmentAsmGen.kt
index 05f9b4ca1..a3ae457a6 100644
--- a/compiler/src/prog8/compiler/target/c64/codegen/assignment/AugmentableAssignmentAsmGen.kt
+++ b/compiler/src/prog8/compiler/target/c64/codegen/assignment/AugmentableAssignmentAsmGen.kt
@@ -182,15 +182,10 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                         }
                     }
                     else -> {
-                        asmgen.assignExpressionToVariable(memory.addressExpression, asmgen.asmVariableName("P8ZP_SCRATCH_W2"), DataType.UWORD, target.scope)
-                        asmgen.out("""
-                            lda  P8ZP_SCRATCH_W2
-                            pha
-                            lda  P8ZP_SCRATCH_W2+1
-                            pha
-                            ldy  #0
-                            lda  (P8ZP_SCRATCH_W2),y
-                            sta  P8ZP_SCRATCH_B1""")
+                        if(asmgen.options.slowCodegenWarnings)
+                            println("warning: slow stack evaluation used (1): ${memory.addressExpression::class.simpleName} at ${memory.addressExpression.position}") // TODO optimize...
+                        asmgen.translateExpression(memory.addressExpression)  // TODO directly into P8ZP_SCRATCH_W2
+                        asmgen.out("  jsr  prog8_lib.read_byte_from_address_on_stack |  sta  P8ZP_SCRATCH_B1")
                         val zp = CompilationTarget.instance.machine.zeropage
                         when {
                             valueLv != null -> inplaceModification_byte_litval_to_variable(zp.SCRATCH_B1.toHex(), DataType.UBYTE, operator, valueLv.toInt())
@@ -202,14 +197,7 @@ internal class AugmentableAssignmentAsmGen(private val program: Program,
                             }
                             else -> inplaceModification_byte_value_to_variable(zp.SCRATCH_B1.toHex(), DataType.UBYTE, operator, value)
                         }
-                        asmgen.out("""
-                            pla
-                            sta  P8ZP_SCRATCH_W2+1
-                            pla
-                            sta  P8ZP_SCRATCH_W2
-                            ldy  #0
-                            lda  P8ZP_SCRATCH_B1
-                            sta  (P8ZP_SCRATCH_W2),y""")
+                        asmgen.out("  lda  P8ZP_SCRATCH_B1 |  jsr  prog8_lib.write_byte_to_address_on_stack | inx")
                     }
                 }
             }
diff --git a/examples/charset.p8 b/examples/charset.p8
index 69926cc67..c0a0d7365 100644
--- a/examples/charset.p8
+++ b/examples/charset.p8
@@ -5,7 +5,6 @@
 %option no_sysinit
 
 ;  Create a custom character set on the C64.
-; TODO why is this one significantly larger than with older compiler?
 
 main {