From cb6d92a9005a21d3c7bdb668d1f2dd8ea47e0295 Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Thu, 12 Jan 2012 02:00:39 -0300
Subject: [PATCH] compiler: -Wundefined to warn about undefined variables (WIP)

Limitations:
- complains about iterative calculations like  avg = A*avg+(1-A)*VALUE
- no way to explicitly initialize variables to zero (making the warning
  go away)
---
 src/compiler/idgen           |  1 +
 src/compiler/parser.y        |  5 ++++
 src/compiler/parser_helper.h |  1 +
 src/compiler/ptest/ptest.c   |  4 +++-
 src/compiler/symtab.h        |  4 +++-
 src/compiler/test/wundef     | 46 ++++++++++++++++++++++++++++++++++++
 6 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100755 src/compiler/test/wundef

diff --git a/src/compiler/idgen b/src/compiler/idgen
index 82fdad7..cad5485 100755
--- a/src/compiler/idgen
+++ b/src/compiler/idgen
@@ -50,6 +50,7 @@ sed 's/#.*//;/^ *$/d' $1 | sort | {
 	.fpvm_sym = { .name = "$1" },
 	.pfv_idx = $2,
 	.pvv_idx = $3,
+	.flags = SF_SYSTEM,
 },
 EOF
 		i=`expr $i + 1`
diff --git a/src/compiler/parser.y b/src/compiler/parser.y
index 3296ec7..d4289ca 100644
--- a/src/compiler/parser.y
+++ b/src/compiler/parser.y
@@ -33,6 +33,7 @@
 
 
 	int warn_section = 0;
+	int warn_undefined = 0;
 
 	struct yyParser;
 	static void yy_parse_failed(struct yyParser *yypParser);
@@ -255,6 +256,7 @@ assignments ::= assignments assignment.
 assignments ::= .
 
 assignment ::= ident(I) TOK_ASSIGN expr(N) opt_semi. {
+	I->sym->flags |= SF_ASSIGNED;
 	state->error = state->comm->assign_default(state->comm, I->sym, N);
 	free(I);
 	if(state->error) {
@@ -477,6 +479,9 @@ primary_expr(N) ::= TOK_CONSTANT(C). {
 }
 
 primary_expr(N) ::= ident(I). {
+	if(warn_undefined && !(I->sym->flags & (SF_SYSTEM | SF_ASSIGNED)))
+		printf("accessing undefined variable %s\n",
+		    I->sym->fpvm_sym.name);
 	N = node(I->token, I->sym, NULL, NULL, NULL);
 	free(I);
 }
diff --git a/src/compiler/parser_helper.h b/src/compiler/parser_helper.h
index 40eb556..8880caf 100644
--- a/src/compiler/parser_helper.h
+++ b/src/compiler/parser_helper.h
@@ -46,6 +46,7 @@ struct parser_comm {
 };
 
 extern int warn_section;
+extern int warn_undefined;
 
 const char *parse(const char *expr, int start_token, struct parser_comm *comm);
 void parse_free_one(struct ast_node *node);
diff --git a/src/compiler/ptest/ptest.c b/src/compiler/ptest/ptest.c
index 69ee21d..232a78f 100644
--- a/src/compiler/ptest/ptest.c
+++ b/src/compiler/ptest/ptest.c
@@ -333,7 +333,7 @@ static void usage(const char *name)
 "  -n runs   run compilation repeatedly (default: run only once)\n"
 "  -q        quiet operation\n"
 "  -s        dump symbol table after parsing (only if -c is not set)\n"
-"  -Wwarning enable compiler warning (one of: section)\n"
+"  -Wwarning enable compiler warning (one of: section, undefined)\n"
     , name);
 	exit(1);
 }
@@ -368,6 +368,8 @@ int main(int argc, char **argv)
 		case 'W':
 			if (!strcmp(optarg, "section"))
 				warn_section = 1;
+			else if (!strcmp(optarg, "undefined"))
+				warn_undefined = 1;
 			else
 				usage(*argv);
 			break;
diff --git a/src/compiler/symtab.h b/src/compiler/symtab.h
index 7781eb3..d623a1c 100644
--- a/src/compiler/symtab.h
+++ b/src/compiler/symtab.h
@@ -14,7 +14,9 @@
 #include <fpvm/symbol.h>
 
 
-#define	SF_FIXED	0
+#define	SF_SYSTEM	(1 << 0)
+#define	SF_ASSIGNED	(1 << 1)
+#define	SF_FIXED	SF_SYSTEM
 
 struct sym {
 	struct fpvm_sym fpvm_sym;
diff --git a/src/compiler/test/wundef b/src/compiler/test/wundef
new file mode 100755
index 0000000..2f038f3
--- /dev/null
+++ b/src/compiler/test/wundef
@@ -0,0 +1,46 @@
+#!/bin/sh
+. ./Common
+
+###############################################################################
+
+ptest "-Wundefined: variable defined per-frame" -q -Wundefined <<EOF
+per_frame:
+	foo = 1
+	bar = foo
+per_vertex:
+	bar = foo
+EOF
+expect <<EOF
+EOF
+
+#------------------------------------------------------------------------------
+
+ptest "-Wundefined: variable defined per-vertex" -q -Wundefined <<EOF
+per_vertex:
+	foo = 1
+	bar = foo
+EOF
+expect <<EOF
+EOF
+
+#------------------------------------------------------------------------------
+
+ptest "-Wundefined: variable undefined in per-frame" -q -Wundefined <<EOF
+per_frame:
+	bar = foo
+EOF
+expect <<EOF
+accessing undefined variable foo
+EOF
+
+#------------------------------------------------------------------------------
+
+ptest "-Wundefined: variable undefined in per-vertex" -q -Wundefined <<EOF
+per_vertex:
+	bar = foo
+EOF
+expect <<EOF
+accessing undefined variable foo
+EOF
+
+###############################################################################