scc

commit afc55f2a912d03aab2cfde5de3ba76de6ece8ac3
parent 42a80b685648b7cb5c417c00b7cc338dcbefc394
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Thu, 12 Feb 2015 12:35:24 +0100

Add optimize function() to cc2

This function runs all the possible optimizations that can be applied.
At this moment only reduction of casting can be used.

Diffstat:
M
cc2/Makefile
 | 
2
+-
M
cc2/cc2.h
 | 
1
+
M
cc2/main.c
 | 
1
+
A
cc2/optm.c
 | 
43
+++++++++++++++++++++++++++++++++++++++++++

4 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/cc2/Makefile b/cc2/Makefile
@@ -1,5 +1,5 @@
 
-OBJS = main.o parser.o cgen.o code.o
+OBJS = main.o parser.o cgen.o code.o optm.o
 
 CPPFLAGS = -I../inc
 LDFLAGS = -L../lib
diff --git a/cc2/cc2.h b/cc2/cc2.h
@@ -117,4 +117,5 @@ extern void genstack(Symbol *fun);
 extern void apply(Node *list[], Node *(*fun)(Node *));
 extern Symbol *parse(void);
 extern void code(char op, ...);
+extern Node *optimize(Node *np);
 extern void prtree(Node *np);
diff --git a/cc2/main.c b/cc2/main.c
@@ -31,6 +31,7 @@ main(void)
 	Symbol *fun;
 
 	while (!feof(stdin) && (fun = parse())) {
+		apply(fun->u.f.body, optimize);
 		apply(fun->u.f.body, genaddable);
 		generate(fun);
 	}
diff --git a/cc2/optm.c b/cc2/optm.c
@@ -0,0 +1,43 @@
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <cc.h>
+#include "cc2.h"
+
+
+#include <stdio.h>
+
+static Node *
+optcasts(Node *np, Type *tp)
+{
+	if (!np)
+		return NULL;
+
+repeat:
+	switch (np->op) {
+	case OCAST:
+		/* TODO: be careful with the sign */
+		if (np->type->c_int && np->type->size >= tp->size) {
+			np = np->left;
+			goto repeat;
+		}
+		break;
+	case OASSIG:
+		tp = np->type;
+		break;
+	default:
+		np->type = tp;
+	}
+
+	np->left = optcasts(np->left, tp);
+	np->right = optcasts(np->right, tp);
+	return np;			
+}
+
+Node *
+optimize(Node *np)
+{
+	np = optcasts(np, np->type);
+	return np;
+}