From 9b634ea6457f946bcad612a1602e92bea21f6c9f Mon Sep 17 00:00:00 2001
From: "Michael D. Lowis" <mike.lowis@gentex.com>
Date: Fri, 30 Apr 2021 09:13:54 -0400
Subject: [PATCH] implemented code generation for if statements. Only the C
 backend for now

---
 cerise/backend/c99/codegen.c    | 23 +++++++++++++++++++++++
 cerise/backend/test/codegen.c   | 15 +++++++++++++++
 cerise/backend/x86_64/codegen.c | 15 +++++++++++++++
 cerise/inc/cerise.h             |  4 ++++
 cerise/src/grammar.c            | 18 +++++++-----------
 cerise/tests/Module.m           | 21 +++++++++++++++++++++
 6 files changed, 85 insertions(+), 11 deletions(-)

diff --git a/cerise/backend/c99/codegen.c b/cerise/backend/c99/codegen.c
index bb14f9a..2df1a3d 100644
--- a/cerise/backend/c99/codegen.c
+++ b/cerise/backend/c99/codegen.c
@@ -206,3 +206,26 @@ void codegen_store(Parser* p, Item* a, Item* b)
         assert(!"bad store op");
     }
 }
+
+void codegen_if(Parser* p, Item* item)
+{
+    load_var(p, item);
+    printf("    if (_T%d) {\n", item->reg);
+}
+
+void codegen_else(Parser* p, Item* item)
+{
+    (void)p, (void)item;
+    printf("    } else {\n");
+}
+
+void codegen_endif(Parser* p, long elsifs, Item* item)
+{
+    (void)p, (void)item;
+    printf("    ");
+    for (long i = 0; i < elsifs; i ++)
+    {
+        printf("}");
+    }
+    printf("}\n");
+}
diff --git a/cerise/backend/test/codegen.c b/cerise/backend/test/codegen.c
index fa252c6..2826e8d 100644
--- a/cerise/backend/test/codegen.c
+++ b/cerise/backend/test/codegen.c
@@ -85,3 +85,18 @@ void codegen_store(Parser* p, Item* a, Item* b)
 {
     (void)p, (void)a, (void)b;
 }
+
+void codegen_if(Parser* p, Item* item)
+{
+    (void)p, (void)item;
+}
+
+void codegen_else(Parser* p, Item* item)
+{
+    (void)p, (void)item;
+}
+
+void codegen_endif(Parser* p, long elsifs, Item* item)
+{
+    (void)p, (void)elsifs, (void)item;
+}
diff --git a/cerise/backend/x86_64/codegen.c b/cerise/backend/x86_64/codegen.c
index 4f8602c..904ca9d 100644
--- a/cerise/backend/x86_64/codegen.c
+++ b/cerise/backend/x86_64/codegen.c
@@ -314,3 +314,18 @@ void codegen_store(Parser* p, Item* a, Item* b)
 //        assert(!"bad store op");
     }
 }
+
+void codegen_if(Parser* p, Item* item)
+{
+    (void)p, (void)item;
+}
+
+void codegen_else(Parser* p, Item* item)
+{
+    (void)p, (void)item;
+}
+
+void codegen_endif(Parser* p, long elsifs, Item* item)
+{
+    (void)p, (void)elsifs, (void)item;
+}
diff --git a/cerise/inc/cerise.h b/cerise/inc/cerise.h
index ec85ec6..f416a53 100644
--- a/cerise/inc/cerise.h
+++ b/cerise/inc/cerise.h
@@ -208,3 +208,7 @@ void codegen_endproc(Parser* p);
 void codegen_unop(Parser* p, int op, Item* a);
 void codegen_binop(Parser* p, int op, Item* a, Item* b);
 void codegen_store(Parser* p, Item* a, Item* b);
+void codegen_if(Parser* p, Item* item);
+void codegen_else(Parser* p, Item* item);
+void codegen_endif(Parser* p, long elsifs, Item* item);
+
diff --git a/cerise/src/grammar.c b/cerise/src/grammar.c
index 51b1547..15e3136 100644
--- a/cerise/src/grammar.c
+++ b/cerise/src/grammar.c
@@ -383,30 +383,26 @@ RULE(statement_seq)
             expect(p, IF);
             expression(p, item);
             check_bool(p, item);
-            // CFJump(item)
+            codegen_if(p, item);
             expect(p, THEN);
             statement_seq(p, &(Item){0});
-            // L = 0
+            int elsifs = 0;
             while (accept(p, ELSIF))
             {
-                // FJump(L)
-                // FixLink(item->imm.i)
+                elsifs++;
+                codegen_else(p, item);
                 expression(p, item);
                 check_bool(p, item);
-                // CFJump(item)
+                codegen_if(p, item);
                 expect(p, THEN);
                 statement_seq(p, &(Item){0});
             }
             if (accept(p, ELSE))
             {
-                // FJump(L)
-                // FixLink(item->imm.i)
+                codegen_else(p, item);
                 statement_seq(p, &(Item){0});
             }
-            else
-            {
-                // FixLink(item->imm.i)
-            }
+            codegen_endif(p, elsifs, item);
             expect(p, END);
         }
         else
diff --git a/cerise/tests/Module.m b/cerise/tests/Module.m
index d73b8e4..f7bc47c 100644
--- a/cerise/tests/Module.m
+++ b/cerise/tests/Module.m
@@ -55,10 +55,31 @@ begin
 #  # Complex arithmetic
 #  c = b + b * b + b;
 #
+
+
+  # If statements
+  if 1 == 1 then
+    c = 1;
+  end
+
+  if 1 == 1 then
+    c = 1;
+  else
+    c = 1;
+  end
+
+  if 1 == 1 then
+    c = 1;
+  elsif 2 == 2 then
+    c = 1;
+  end
+
   if 1 == 1 then
     c = 1;
   elsif 2 == 2 then
     c = 2;
+  elsif 2 == 2 then
+    c = 2;
   else
     c = 3;
   end
-- 
2.49.0