harec

commit 0edcd481417b331394a92b4214f4bb20274c934b
parent d3e678086ae45b9297075860ec28a4a360dc7d98
Author: Drew DeVault <sir@cmpwn.com>
Date:   Tue, 29 Dec 2020 13:25:59 -0500

gen: implement if expressions

Diffstat:
M
src/gen.c
 | 
37
++++++++++++++++++++++++++++++++++++-
M
src/parse.c
 | 
2
++

2 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/src/gen.c b/src/gen.c
@@ -589,6 +589,39 @@ gen_expr_constant(struct gen_context *ctx,
 }
 
 static void
+gen_expr_if(struct gen_context *ctx,
+	const struct expression *expr,
+	const struct qbe_value *out)
+{
+	struct qbe_value cond = {0};
+	gen_temp(ctx, &cond, &qbe_word, "cond.%d");
+	gen_expression(ctx, expr->_if.cond, &cond);
+
+	struct qbe_statement tlabel = {0}, flabel = {0}, endl = {0};
+	struct qbe_value tbranch = {0}, fbranch = {0}, end = {0};
+	tbranch.kind = QV_LABEL;
+	tbranch.name = strdup(genl(&tlabel, &ctx->id, "branch_true.%d"));
+	fbranch.kind = QV_LABEL;
+	fbranch.name = strdup(genl(&flabel, &ctx->id, "branch_false.%d"));
+	end.name = strdup(genl(&endl, &ctx->id, "end.%d"));
+	end.kind = QV_LABEL;
+
+	pushi(ctx->current, NULL, Q_JNZ, &cond, &tbranch, &fbranch, NULL);
+
+	push(&ctx->current->body, &tlabel);
+	gen_expression(ctx, expr->_if.true_branch, out);
+	pushi(ctx->current, NULL, Q_JMP, &end, NULL);
+
+	push(&ctx->current->body, &flabel);
+	if (expr->_if.false_branch) {
+		gen_expression(ctx, expr->_if.false_branch, out);
+		pushi(ctx->current, NULL, Q_JMP, &end, NULL);
+	}
+
+	push(&ctx->current->body, &endl);
+}
+
+static void
 gen_expr_list(struct gen_context *ctx,
 	const struct expression *expr,
 	const struct qbe_value *out)
@@ -737,8 +770,10 @@ gen_expression(struct gen_context *ctx,
 		break;
 	case EXPR_CONTINUE:
 	case EXPR_FOR:
-	case EXPR_IF:
 		assert(0); // TODO
+	case EXPR_IF:
+		gen_expr_if(ctx, expr, out);
+		break;
 	case EXPR_LIST:
 		gen_expr_list(ctx, expr, out);
 		break;
diff --git a/src/parse.c b/src/parse.c
@@ -1297,6 +1297,7 @@ parse_simple_expression(struct parser *par)
 static struct ast_expression *
 parse_if_expression(struct parser *par)
 {
+	trenter(TR_PARSE, "if");
 	struct ast_expression *exp = xcalloc(1, sizeof(struct ast_expression));
 	exp->type = EXPR_IF;
 
@@ -1322,6 +1323,7 @@ parse_if_expression(struct parser *par)
 		break;
 	}
 
+	trleave(TR_PARSE, NULL);
 	return exp;
 }