From c984ace5c59014b96ea40f3d2fb84dca7f865395 Mon Sep 17 00:00:00 2001
From: Kartik Agaram <vc@akkartik.com>
Date: Sat, 29 Feb 2020 22:53:00 -0800
Subject: 6074

---
 apps/mu.subx | 46 +++++++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 21 deletions(-)

(limited to 'apps/mu.subx')

diff --git a/apps/mu.subx b/apps/mu.subx
index 4004aa69..57ae56bc 100644
--- a/apps/mu.subx
+++ b/apps/mu.subx
@@ -5685,7 +5685,7 @@ $emit-subx-stmt-list:check-for-reg-var-def:
         0f 85/jump-if-!= break/disp32
 $emit-subx-stmt-list:reg-var-def:
         # TODO: ensure that there's exactly one output
-        (emit-subx-reg-var-spill *(ebp+8) %ecx)
+        (compute-reg-and-maybe-emit-spill *(ebp+8) %ecx)
         # register variable definition
         (push *(ebp+0x10) %eax)
         # emit the instruction as usual
@@ -5714,19 +5714,7 @@ $emit-subx-stmt-list:end:
     5d/pop-to-ebp
     c3/return
 
-$emit-subx-stmt-list:abort-reg-var-def-without-register:
-    # error("var '" var->name "' initialized from an instruction must live in a register\n")
-    (write-buffered Stderr "var '")
-    (write-buffered Stderr *eax)  # Var-name
-    (write-buffered Stderr "' initialized from an instruction must live in a register\n")
-    (flush Stderr)
-    # . syscall(exit, 1)
-    bb/copy-to-ebx  1/imm32
-    b8/copy-to-eax  1/imm32/exit
-    cd/syscall  0x80/imm8
-    # never gets here
-
-emit-subx-reg-var-spill:  # out: (addr buffered-file), stmt: (handle stmt)
+compute-reg-and-maybe-emit-spill:  # out: (addr buffered-file), stmt: (handle reg-var-def) -> result/eax: (handle var)
     # . prologue
     55/push-ebp
     89/<- %ebp 4/r32/esp
@@ -5734,18 +5722,22 @@ emit-subx-reg-var-spill:  # out: (addr buffered-file), stmt: (handle stmt)
     51/push-ecx
     # ecx = stmt
     8b/-> *(ebp+0xc) 1/r32/ecx
-    # var output/eax: (handle var) = curr-stmt->outputs->value
-    8b/-> *(ecx+0xc) 0/r32/eax
-    8b/-> *eax 0/r32/eax
+    # var output/ecx: (handle var) = curr-stmt->outputs->value
+    8b/-> *(ecx+0xc) 1/r32/ecx  # Regvardef-inouts
+    8b/-> *ecx 1/r32/ecx  # List-value
+    # var reg/eax: (handle array byte) = output->register
+    8b/-> *(ecx+0x10) 0/r32/eax  # Var-register
     # ensure that output is in a register
-    81 7/subop/compare *(eax+0x10) 0/imm32  # Var-register
-    0f 84/jump-if-= $emit-subx-stmt-list:abort-reg-var-def-without-register/disp32
+    3d/compare-eax-and 0/imm32
+    0f 84/jump-if-= $compute-reg-and-maybe-emit-spill:abort-reg-var-def-without-register/disp32
     # emit spill
     (emit-indent *(ebp+8) *Curr-block-depth)
     (write-buffered *(ebp+8) "ff 6/subop/push %")
-    (write-buffered *(ebp+8) *(eax+0x10))
+    (write-buffered *(ebp+8) %eax)
     (write-buffered *(ebp+8) Newline)
-$emit-subx-reg-var-spill:end:
+$compute-reg-and-maybe-emit-spill:end:
+    # return ecx
+    89/<- %eax 1/r32/ecx
     # . restore registers
     59/pop-to-ecx
     # . epilogue
@@ -5753,6 +5745,18 @@ $emit-subx-reg-var-spill:end:
     5d/pop-to-ebp
     c3/return
 
+$compute-reg-and-maybe-emit-spill:abort-reg-var-def-without-register:
+    # error("var '" var->name "' initialized from an instruction must live in a register\n")
+    (write-buffered Stderr "var '")
+    (write-buffered Stderr *eax)  # Var-name
+    (write-buffered Stderr "' initialized from an instruction must live in a register\n")
+    (flush Stderr)
+    # . syscall(exit, 1)
+    bb/copy-to-ebx  1/imm32
+    b8/copy-to-eax  1/imm32/exit
+    cd/syscall  0x80/imm8
+    # never gets here
+
 emit-subx-cleanup-and-unconditional-nonlocal-branch:  # out: (addr buffered-file), stmt: (addr stmt1), vars: (addr stack (handle var))
     # . prologue
     55/push-ebp
-- 
cgit 1.4.1-2-gfad0