From 5cf79243529ea770d5ee465f6baa026786e76a94 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Mon, 24 Jan 2022 16:50:15 +0900
Subject: [PATCH] [qfcc] Improve dags handling of auxiliary use ops

The aux use ops need to be counted and given nodes explicitly as they
may refer to defs that are not accessed by other statements other than
by aliases, and those aliases need to be marked live as well as the used
def.
---
 tools/qfcc/source/dags.c | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/tools/qfcc/source/dags.c b/tools/qfcc/source/dags.c
index a128422cc..ac3a36a63 100644
--- a/tools/qfcc/source/dags.c
+++ b/tools/qfcc/source/dags.c
@@ -66,6 +66,8 @@ static dag_t *dags_freelist;
 
 static daglabel_t *daglabel_chain;
 
+static void dag_live_aliases(operand_t *op);
+
 static void
 flush_daglabels (void)
 {
@@ -453,6 +455,7 @@ dagnode_set_edges (dag_t *dag, dagnode_t *n, statement_t *s)
 		}
 		daglabel_t *label = operand_label (dag, use);
 		label->live = 1;
+		dag_live_aliases (use);
 		set_add (n->edges, label->dagnode->number);
 	}
 	if (n->type == st_func) {
@@ -815,6 +818,7 @@ dag_create (flownode_t *flownode)
 	dagnode_t **nodes;
 	daglabel_t **labels;
 	int         num_statements = 0;
+	int         num_use = 0;
 	int         num_nodes;
 	int         num_lables;
 	set_t      *live_vars = set_new ();
@@ -823,18 +827,25 @@ dag_create (flownode_t *flownode)
 
 	// count the number of statements so the number of nodes and labels can be
 	// guessed
-	for (s = block->statements; s; s = s->next)
+	for (s = block->statements; s; s = s->next) {
 		num_statements++;
+		for (operand_t *use = s->use; use; use = use->next) {
+			if (use->op_type == op_pseudo) {
+				continue;
+			}
+			num_use++;
+		}
+	}
 
 	set_assign (live_vars, flownode->live_vars.out);
 
 	dag = new_dag ();
 	dag->flownode = flownode;
-	// at most FLOW_OPERANDS per statement
-	num_nodes = num_statements * FLOW_OPERANDS;
+	// at most FLOW_OPERANDS per statement + use
+	num_nodes = num_statements * FLOW_OPERANDS + num_use;
 	dag->nodes = alloca (num_nodes * sizeof (dagnode_t));
-	// at most FLOW_OPERANDS per statement, + return + params
-	num_lables = num_statements * (FLOW_OPERANDS + 1 + 8);
+	// at most FLOW_OPERANDS per statement, + return + params + use
+	num_lables = num_statements * (FLOW_OPERANDS + 1 + 8) + num_use;
 	dag->labels = alloca (num_lables * sizeof (daglabel_t));
 	dag->roots = set_new ();
 
@@ -843,6 +854,15 @@ dag_create (flownode_t *flownode)
 	for (s = block->statements; s; s = s->next) {
 		operand_t  *operands[FLOW_OPERANDS];
 		dag_make_leafs (dag, s, operands);
+		// make sure any auxiliary operands are given nodes, too
+		for (operand_t *use = s->use; use; use = use->next) {
+			if (use->op_type == op_pseudo) {
+				continue;
+			}
+			if (!dag_node (use)) {
+				leaf_node (dag, use, s->expr);
+			}
+		}
 	}
 	// actual dag creation
 	for (s = block->statements; s; s = s->next) {