From 2eae07de728129026fcaf93ad3999a40fb48fb19 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Sat, 6 May 2017 17:30:14 +0200
Subject: [PATCH] mescc: Support ==, != as expression value.

* module/mes/as-i386.scm: Export them.
* module/language/c99/compiler.mes (expr->accu): Set accu to 0/1 for eq, ne.
* module/mes/as-i386.mes (i386:nz->accu, i386:z->accu,
  i386:accu<->stack): New functions.
* scaffold/t.c (math_test): Test it.
---
 module/language/c99/compiler.mes | 15 ++++++++++++---
 module/mes/as-i386.mes           | 11 +++++++++++
 module/mes/as-i386.scm           |  4 ++++
 scaffold/t.c                     |  6 ++++++
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/module/language/c99/compiler.mes b/module/language/c99/compiler.mes
index 1bc6900c..2b554781 100644
--- a/module/language/c99/compiler.mes
+++ b/module/language/c99/compiler.mes
@@ -712,11 +712,20 @@
                                    (wrap-as (i386:value->accu 0))
                                    (wrap-as (i386:sub-base)))))
 
-        ((eq ,a ,b) ((binop->accu info) a b (i386:sub-base)))
+        ((eq ,a ,b) ((binop->accu info) a b (append (i386:sub-base) (i386:z->accu))))
         ((ge ,a ,b) ((binop->accu info) b a (i386:sub-base)))
         ((gt ,a ,b) ((binop->accu info) b a (i386:sub-base)))
-        ((ne ,a ,b) ((binop->accu info) a b (append (i386:sub-base)
-                                                    (i386:xor-zf))))
+
+        ;; FIXME: set accu *and* flags
+        ((ne ,a ,b) ((binop->accu info) a b (append (i386:push-accu)
+                                                    (i386:sub-base)
+                                                    (i386:nz->accu)
+                                                    (i386:accu<->stack)
+                                                    (i386:sub-base)
+                                                    (i386:xor-zf)
+                                                    (i386:pop-accu))))
+
+        ((ne ,a ,b) ((binop->accu info) a b (append (i386:sub-base) (i386:xor-zf))))
         ((le ,a ,b) ((binop->accu info) b a (i386:base-sub)))
         ((lt ,a ,b) ((binop->accu info) b a (i386:base-sub)))
 
diff --git a/module/mes/as-i386.mes b/module/mes/as-i386.mes
index 3ffa6448..0de8c92b 100644
--- a/module/mes/as-i386.mes
+++ b/module/mes/as-i386.mes
@@ -483,3 +483,14 @@
 (define (i386:base-sub)
   `(#x29 #xc2))                         ; sub    %eax,%edx
 
+(define (i386:nz->accu)
+  '(#x0f #x95 #xc0                      ; setne   %al
+         #x0f #xb6 #xc0))               ; movzbl %al,%eax
+
+(define (i386:z->accu)
+  '(#x0f #x94 #xc0                      ; sete   %al
+         #x0f #xb6 #xc0))               ; movzbl %al,%eax
+
+(define (i386:accu<->stack)
+  '(#x87 #x04 #x24))                    ; xchg   %eax,(%esp)
+
diff --git a/module/mes/as-i386.scm b/module/mes/as-i386.scm
index b5e1c8f8..a55ddac8 100644
--- a/module/mes/as-i386.scm
+++ b/module/mes/as-i386.scm
@@ -148,6 +148,10 @@
             i386:accu+n
             i386:base+n
             i386:base-address->accu-address
+
+            i386:nz->accu
+            i386:z->accu
+            i386:accu<->stack
             ))
 
 (include-from-path "mes/as-i386.mes")
diff --git a/scaffold/t.c b/scaffold/t.c
index 227efca1..8ad92369 100644
--- a/scaffold/t.c
+++ b/scaffold/t.c
@@ -341,6 +341,12 @@ math_test ()
   puts ("t: ^ 1 \n");
   if ((1 ^ 3) != 2) return 1;
 
+  puts ("t: 3 == 3\n");
+  if ((3 == 3) !=  1) return 1;
+
+  puts ("t: 3 != 3\n");
+  if ((3 != 3) !=  0) return 1;
+
   return array_test (env);
 }