[hackers] [scc] [cc2-qbe] Implement switch statements || Roberto E. Vargas Caballero

From: <git_AT_suckless.org>
Date: Mon, 26 Sep 2016 12:00:42 +0200 (CEST)

commit 28b4043893d831ce7209dc413e7ce43047de3da0
Author: Roberto E. Vargas Caballero <roberto.vargas_AT_igrid-td.com>
AuthorDate: Mon Sep 26 11:41:01 2016 +0200
Commit: Roberto E. Vargas Caballero <roberto.vargas_AT_igrid-td.com>
CommitDate: Mon Sep 26 11:41:01 2016 +0200

    [cc2-qbe] Implement switch statements
    
    This is a first implementation of switches, which uses a if-else-if
    chain. At this point we cannot implement any other form of switch
    because we need support for indirect jump in qbe.

diff --git a/cc2/arch/qbe/cgen.c b/cc2/arch/qbe/cgen.c
index 7e41be2..b3eef3c 100644
--- a/cc2/arch/qbe/cgen.c
+++ b/cc2/arch/qbe/cgen.c
_AT_@ -414,6 +414,47 @@ function(void)
         return NULL;
 }
 
+static void
+swtch_if(Node *idx)
+{
+ Node aux1, aux2, *np;
+ Symbol *deflabel = NULL;
+
+ for (;;) {
+ np = delstmt();
+ setlabel(np->label);
+
+ switch (np->op) {
+ case OESWITCH:
+ if (deflabel) {
+ aux1.op = OJMP;
+ aux1.label = NULL;
+ aux1.u.sym = deflabel;
+ cgen(&aux1);
+ }
+ return;
+ case OCASE:
+ aux1 = *np;
+ aux1.op = OBRANCH;
+ aux1.label = NULL;
+ aux1.left = &aux2;
+
+ aux2.op = OEQ;
+ aux2.type = idx->type;
+ aux2.left = np->left;
+ aux2.right = idx;
+
+ cgen(&aux1);
+ break;
+ case ODEFAULT:
+ deflabel = np->u.sym;
+ break;
+ default:
+ abort();
+ }
+ }
+}
+
 static Node *
 rhs(Node *np, Node *ret)
 {
_AT_@ -550,11 +591,6 @@ rhs(Node *np, Node *ret)
                 return lhs(l, ret);
         case OFIELD:
                 return field(np, ret, 0);
- case OCASE:
- case ODEFAULT:
- case OESWITCH:
- case OBSWITCH:
- /* TODO: implement these operators */
         default:
                 abort();
         }
_AT_@ -586,6 +622,10 @@ cgen(Node *np)
                 p = (np->left) ? rhs(np->left, &ret) : NULL;
                 code(ASRET, NULL, p, NULL);
                 break;
+ case OBSWITCH:
+ p = rhs(np->left, &ret);
+ swtch_if(p);
+ break;
         default:
                 rhs(np, &ret);
                 break;
Received on Mon Sep 26 2016 - 12:00:42 CEST