[hackers] [scc] Add fold of constants in add and sub operators || Roberto E. Vargas Caballero

From: <git_AT_suckless.org>
Date: Tue, 21 Jul 2015 17:58:25 +0200 (CEST)

commit 149b464dcae2f20abdfed12cf9f7f78ed7596772
Author: Roberto E. Vargas Caballero <k0ga_AT_shike2.com>
AuthorDate: Tue Jul 21 17:56:59 2015 +0200
Commit: Roberto E. Vargas Caballero <k0ga_AT_shike2.com>
CommitDate: Tue Jul 21 17:56:59 2015 +0200

    Add fold of constants in add and sub operators
    
    This is the first step towards constant expressions resolution.

diff --git a/cc1/cc1.h b/cc1/cc1.h
index 8ec77f7..eb65613 100644
--- a/cc1/cc1.h
+++ b/cc1/cc1.h
_AT_@ -23,6 +23,7 @@ struct type {
         unsigned char ns;
         char letter; /* letter of the type */
         bool defined; /* type defined */
+ bool sign; /* signess of the type */
         size_t size; /* sizeof the type */
         size_t align; /* align of the type */
         Type *type; /* base type */
_AT_@ -43,7 +44,8 @@ struct symbol {
         unsigned char token;
         short flags;
         union {
- int i;
+ TINT i;
+ TUINT u;
                 char *s;
                 unsigned char token;
         } u;
_AT_@ -320,6 +322,7 @@ extern Node *varnode(Symbol *sym);
 extern Node *constnode(Symbol *sym);
 extern Node *sizeofnode(Type *tp);
 extern void freetree(Node *np);
+extern Node *simplify(Node *np);
 
 /* expr.c */
 extern Node *expr(void), *negate(Node *np), *constexpr(void);
diff --git a/cc1/code.c b/cc1/code.c
index d7aec72..c4f43c2 100644
--- a/cc1/code.c
+++ b/cc1/code.c
_AT_@ -124,6 +124,15 @@ void (*opcode[])(unsigned, void *) = {
         [OSWITCH] = emitswitch
 };
 
+static Node *simple_sub(Node *), *simple_add(Node *);
+
+static Node *(*opsimp[])(Node *) = {
+ [OADD] = simple_add,
+ [OSUB] = simple_sub
+
+};
+
+
 void
 freetree(Node *np)
 {
_AT_@ -310,16 +319,10 @@ node(unsigned op, Type *tp, Node *lp, Node *rp)
         np->op = op;
         np->type = tp;
         np->sym = NULL;
- np->symbol = np->lvalue = 0;
- np->constant = 1;
+ np->constant = np->symbol = np->lvalue = 0;
         np->left = lp;
         np->right = rp;
 
- if (lp)
- np->constant &= lp->constant;
- if (rp)
- np->constant &= rp->constant;
-
         return np;
 }
 
_AT_@ -359,3 +362,55 @@ sizeofnode(Type *tp)
         sym->u.i = tp->size;
         return constnode(sym);
 }
+
+static Node *
+simple_add(Node *np)
+{
+ Node *lp = np->left, *rp = np->right;
+ Type *tp = np->type;
+ Symbol *sym, *ls = lp->sym, *rs = rp->sym;
+
+ switch (tp->op) {
+ case INT:
+ sym = newsym(NS_IDEN);
+ sym->type = tp;
+ if (tp->sign)
+ sym->u.i = ls->u.i + rs->u.i;
+ else
+ sym->u.u = ls->u.u + rs->u.u;
+ freetree(np);
+ return constnode(sym);
+ default:
+ return np;
+ }
+}
+
+static Node *
+simple_sub(Node *np)
+{
+ Node *lp = np->left, *rp = np->right;
+ Type *tp = np->type;
+ Symbol *sym, *ls = lp->sym, *rs = rp->sym;
+
+ switch (tp->op) {
+ case INT:
+ sym = newsym(NS_IDEN);
+ sym->type = tp;
+ if (tp->sign)
+ sym->u.i = ls->u.i - rs->u.i;
+ else
+ sym->u.u = ls->u.u - rs->u.u;
+ freetree(np);
+ return constnode(sym);
+ default:
+ return np;
+ }
+}
+
+Node *
+simplify(Node *np)
+{
+ if (!np->left->constant || !np->right->constant)
+ return np;
+ return (*opsimp[np->op])(np);
+}
diff --git a/cc1/expr.c b/cc1/expr.c
index 2354771..a00db59 100644
--- a/cc1/expr.c
+++ b/cc1/expr.c
_AT_@ -685,6 +685,7 @@ add(void)
                 }
                 next();
                 np = arithmetic(op, np, mul());
+ np = simplify(np);
         }
 }
 
diff --git a/cc1/types.c b/cc1/types.c
index 0a20ffd..851a03d 100644
--- a/cc1/types.c
+++ b/cc1/types.c
_AT_@ -42,6 +42,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 1,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_SCHAR
         },
         { /* 4 = uchartype */
_AT_@ -58,6 +59,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 1,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_CHAR
         },
         { /* 6 = ushortype */
_AT_@ -74,6 +76,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 2,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_SHORT
         },
         { /* 8 = uinttype */
_AT_@ -90,6 +93,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 2,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_INT
         },
         { /* 10 = longtype */
_AT_@ -98,6 +102,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 4,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_LONG
         },
         { /* 11 = ulongtype */
_AT_@ -122,6 +127,7 @@ static Type types[] = {
                 .defined = 1,
                 .size = 8,
                 .align = 1,
+ .sign = 1,
                 .n.rank = RANK_LLONG
         },
         { /* 14 = floattype */
diff --git a/inc/cc.h b/inc/cc.h
index f21894d..ee51d01 100644
--- a/inc/cc.h
+++ b/inc/cc.h
_AT_@ -8,7 +8,9 @@ typedef unsigned bool;
 #endif
 
 #define TINT short
+#define TUINT unsigned short
 #define TLONG long
+#define TULONG unsigned long
 
 #define RANK_BOOL 0
 #define RANK_SCHAR 1
Received on Tue Jul 21 2015 - 17:58:25 CEST