From b74c8e7fd16184a9fb1f03230258845c78a43dd5 Mon Sep 17 00:00:00 2001
From: Pat Gavlin <pgavlin@gmail.com>
Date: Tue, 21 May 2019 15:44:01 -0700
Subject: [PATCH] WIP: attempt to fix spill code

The results of targeting inserted reloads were being silently discarded,
which resulted in #76. These changes stop discarding these results and
label/reduce any resulting copies.
---
 Utils/lcc/lburg/lburg.c | 11 +++++++++++
 Utils/lcc/src/config.h  |  1 +
 Utils/lcc/src/gen.c     | 19 +++++++++++--------
 Utils/lcc/src/gt1.md    | 14 +++++++++++++-
 4 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/Utils/lcc/lburg/lburg.c b/Utils/lcc/lburg/lburg.c
index 846556a22..45c044ef5 100755
--- a/Utils/lcc/lburg/lburg.c
+++ b/Utils/lcc/lburg/lburg.c
@@ -644,6 +644,17 @@ static void emitstring(Rule rules) {
 		print(",%1/* %R */\n", r);
 	}
 	print("};\n");
+	print("static char *%Pactionnames[] = {\n");
+	print("/* 0 */%10,\n");
+	for (r = rules; r; r = r->link) {
+		print("/* %d */%1", r->ern);
+		if (r->action->code == 0)
+			print("0");
+		else
+			print("\"%s\"", r->action->code);
+		print(",%1/* %R */\n", r);
+	}
+	print("};\n");
 	print("static char *%Ptemplates[] = {\n");
 	print("/* 0 */%10,\n");
 	for (r = rules; r; r = r->link) {
diff --git a/Utils/lcc/src/config.h b/Utils/lcc/src/config.h
index 0a11978ef..7d14a185b 100755
--- a/Utils/lcc/src/config.h
+++ b/Utils/lcc/src/config.h
@@ -14,6 +14,7 @@ typedef struct {
 	void (*_kids)(Node, int, Node*);
 	char **_string;
 	Action *_actions;
+	char **_actionnames;
 	char **_templates;
 	char *_isinstruction;
 	char **_ntname;
diff --git a/Utils/lcc/src/gen.c b/Utils/lcc/src/gen.c
index f4c316d01..dcd2da888 100755
--- a/Utils/lcc/src/gen.c
+++ b/Utils/lcc/src/gen.c
@@ -333,10 +333,10 @@ static void dumprule(int rulenum) {
 
 	char *str = IR->x._templates[rulenum];
 	if (str == 0)
-		str = "(action)\n";
+		str = IR->x._actionnames[rulenum];
 
 	fprint(stderr, "%s / %s", IR->x._string[rulenum], str);
-	if (!IR->x._isinstruction[rulenum])
+	if (!IR->x._isinstruction[rulenum] || IR->x._templates[rulenum] == 0)
 		fprint(stderr, "\n");
 }
 unsigned emitasm(Node p, int nt) {
@@ -357,7 +357,7 @@ unsigned emitasm(Node p, int nt) {
 	if (rulenum == 0) {
 		debug(fprint(stderr, " (no rule)\n"));
 	} else if (fmt == 0) {
-		debug(fprint(stderr, " (action)\n"));
+		debug(fprint(stderr, " %s\n", IR->x._actionnames[rulenum]));
 	} else {
 		debug(fprint(stderr, " %s\n", fmt));
 	}
@@ -775,7 +775,7 @@ static void genspill(Symbol r, Node last, Symbol tmp) {
 	Symbol s;
 	unsigned ty;
 
-	debug(fprint(stderr, "(spilling %s to local %s)\n", r->x.name, tmp->x.name));
+	debug(fprint(stderr, "(spilling %s to local %s after %x)\n", r->x.name, tmp->x.name, last));
 	debug(fprint(stderr, "(genspill: "));
 	debug(dumptree(last));
 	debug(fprint(stderr, ")\n"));
@@ -803,7 +803,7 @@ static void genreload(Node p, Symbol tmp, int i) {
 	Node q;
 	int ty;
 
-	debug(fprint(stderr, "(replacing %x with a reload from %s)\n", p->x.kids[i], tmp->x.name));
+	debug(fprint(stderr, "(replacing %x with a reload from %s before %x)\n", p->x.kids[i], tmp->x.name, p));
 	debug(fprint(stderr, "(genreload: "));
 	debug(dumptree(p->x.kids[i]));
 	debug(fprint(stderr, ")\n"));
@@ -817,7 +817,7 @@ static void genreload(Node p, Symbol tmp, int i) {
 	linearize(p->x.kids[i], p);
 }
 static int reprune(Node *pp, int k, int n, Node p) {
-	struct node x, *q = *pp;
+	struct node *q = *pp;
 
 	if (q == NULL || k > n)
 		return k;
@@ -827,8 +827,11 @@ static int reprune(Node *pp, int k, int n, Node p) {
 	if (k == n) {
 		debug(fprint(stderr, "(reprune changes %x from %x to %x)\n", pp, *pp, p->x.kids[n]));
 		*pp = p->x.kids[n];
-		x = *p;
-		(IR->x.target)(&x);
+		(IR->x.target)(p);
+
+		(*IR->x._label)(p->kids[n]);
+		debug(dumpcover(p->kids[n], 1, 0));
+		reduce(p->kids[n], 1);
 	}
 	return k + 1;
 }
diff --git a/Utils/lcc/src/gt1.md b/Utils/lcc/src/gt1.md
index 30256e43f..945d11c5a 100644
--- a/Utils/lcc/src/gt1.md
+++ b/Utils/lcc/src/gt1.md
@@ -836,9 +836,20 @@ static void inst_spill(Node p) {
 	// inst_spill is essentially the same as inst_stloc, but covers an entire spill tree to avoid reentry in the
 	// spiller when spilling vAC.
 	Node vregp = p->kids[1]->kids[0]->kids[0];
-	assert(getregnum(vregp) == 0);
+
+	// If we are spilling vAC, we're all set. Otherwise we've got some extra work to do to avoid clobbering vAC.
+	int regnum = vregp->syms[0]->x.regnode->number;
+	if (regnum != 0) {
+		print("asm.stw('ht')\n");
+		print("asm.ldw('r%d')\n", regnum);
+	}
+
 	setreg(p->kids[1], wregs[0]);
 	inst_stloc(p);
+
+	if (regnum != 0) {
+		print("asm.ldw('ht')\n");
+	}
 }
 
 static void inst_blkcopy(Node p) {
@@ -1428,6 +1439,7 @@ Interface gt1IR = {
 		_kids,
 		_string,
 		_actions,
+		_actionnames,
 		_templates,
 		_isinstruction,
 		_ntname,