improve -Wcontext code and messages

This builds on my previous code improving the code and the messages,
the messages now always tell you the expected and actual context
value. Also add another test since I had mentioned that case.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

5 files changed, 307 insertions, 120 deletions

diff --git a/sparse.c b/sparse.c
index fcd7487..c01e8cd 100644
--- a/sparse.c
+++ b/sparse.c
@@ -42,7 +42,8 @@ static const char *context_name(struct context *context)
 	return unnamed_context;
 }
 
-static void context_add(struct context_check_list **ccl, const char *name, int offs, int offs_false)
+static void context_add(struct context_check_list **ccl, const char *name,
+			int offs, int offs_false)
 {
 	struct context_check *check, *found = NULL;
 
@@ -63,16 +64,19 @@ static void context_add(struct context_check_list **ccl, const char *name, int o
 	found->val_false += offs_false;
 }
 
-static int imbalance(struct entrypoint *ep, struct position pos, const char *name, const char *why)
+#define IMBALANCE_IN "context imbalance in '%s': "
+#define DEFAULT_CONTEXT_DESCR "   default context: "
+
+static void get_context_string(char **buf, const char **name)
 {
-	if (Wcontext) {
-		struct symbol *sym = ep->name;
-		if (strcmp(name, unnamed_context))
-			warning(pos, "context imbalance in '%s' - %s (%s)", show_ident(sym->ident), why, name);
-		else
-			warning(pos, "context imbalance in '%s' - %s", show_ident(sym->ident), why);
+	if (strcmp(*name, unnamed_context)) {
+		*buf = malloc(strlen(*name) + 16);
+		sprintf(*buf, "   context '%s': ", *name);
+		*name = *buf;
+	} else {
+		*name = DEFAULT_CONTEXT_DESCR;
+		*buf = NULL;
 	}
-	return -1;
 }
 
 static int context_list_check(struct entrypoint *ep, struct position pos,
@@ -81,6 +85,8 @@ static int context_list_check(struct entrypoint *ep, struct position pos,
 {
 	struct context_check *c1, *c2;
 	int cur, tgt;
+	const char *name;
+	char *buf;
 
 	/* make sure the loop below checks all */
 	FOR_EACH_PTR(ccl_target, c1) {
@@ -98,15 +104,131 @@ static int context_list_check(struct entrypoint *ep, struct position pos,
 			break;
 		} END_FOR_EACH_PTR(c2);
 
+		if (cur == tgt || !Wcontext)
+			continue;
+
 		if (cur > tgt)
-			return imbalance(ep, pos, c1->name, "wrong count at exit");
+			warning(pos, IMBALANCE_IN "wrong count at exit",
+				show_ident(ep->name->ident));
 		else if (cur < tgt)
-			return imbalance(ep, pos, c1->name, "unexpected unlock");
+			warning(pos, IMBALANCE_IN "unexpected unlock",
+				show_ident(ep->name->ident));
+
+		name = c1->name;
+		get_context_string(&buf, &name);
+
+		info(pos, "%swanted %d, got %d",
+		     name, tgt, cur);
+
+		free(buf);
+
+		return -1;
 	} END_FOR_EACH_PTR(c1);
 
 	return 0;
 }
 
+static int handle_call(struct entrypoint *ep, struct basic_block *bb,
+		       struct instruction *insn,
+		       struct context_check_list *combined)
+{
+	struct context *ctx;
+	struct context_check *c;
+	const char *name, *call, *cmp;
+	char *buf;
+	int val, ok;
+
+	if (!insn->func || !insn->func->sym ||
+	    insn->func->type != PSEUDO_SYM)
+		return 0;
+
+	/*
+	 * Check all contexts the function wants.
+	 */
+	FOR_EACH_PTR(insn->func->sym->ctype.contexts, ctx) {
+		name = context_name(ctx);
+		val = 0;
+
+		FOR_EACH_PTR(combined, c) {
+			if (strcmp(c->name, name) == 0) {
+				val = c->val;
+				break;
+			}
+		} END_FOR_EACH_PTR(c);
+
+		if (ctx->exact) {
+			ok = ctx->in == val;
+			cmp = "";
+		} else {
+			ok = ctx->in <= val;
+			cmp = ">= ";
+		}
+
+		if (!ok && Wcontext) {
+			get_context_string(&buf, &name);
+			call = strdup(show_ident(insn->func->ident));
+
+			warning(insn->pos, "context problem in '%s': "
+				"'%s' expected different context",
+				show_ident(ep->name->ident), call);
+
+			info(insn->pos, "%swanted %s%d, got %d",
+			     name, cmp, ctx->in, val);
+
+			free((void *)call);
+			free(buf);
+
+			return -1;
+		}
+	} END_FOR_EACH_PTR (ctx);
+
+	return 0;
+}
+
+static int handle_context(struct entrypoint *ep, struct basic_block *bb,
+			  struct instruction *insn,
+			  struct context_check_list **combined)
+{
+	struct context_check *c;
+	const char *name;
+	char *buf;
+	int val, ok;
+
+	val = 0;
+
+	name = unnamed_context;
+	if (insn->context_expr)
+		name = show_ident(insn->context_expr->symbol_name);
+
+	FOR_EACH_PTR(*combined, c) {
+		if (strcmp(c->name, name) == 0) {
+			val = c->val;
+			break;
+		}
+	} END_FOR_EACH_PTR(c);
+
+	ok = insn->required <= val;
+
+	if (!ok && Wcontext) {
+		get_context_string(&buf, &name);
+
+		warning(insn->pos,
+			IMBALANCE_IN
+			"__context__ statement expected different context",
+			show_ident(ep->name->ident));
+
+		info(insn->pos, "%swanted >= %d, got %d",
+		     name, insn->required, val);
+
+		free(buf);
+		return -1;
+	}
+
+	context_add(combined, name, insn->increment, insn->inc_false);
+
+	return 0;
+}
+
 static int check_bb_context(struct entrypoint *ep, struct basic_block *bb,
 			    struct context_check_list *ccl_in,
 			    struct context_check_list *ccl_target,
@@ -116,16 +238,21 @@ static int check_bb_context(struct entrypoint *ep, struct basic_block *bb,
 	struct context_check *c;
 	struct instruction *insn;
 	struct multijmp *mj;
-	struct context *ctx;
-	const char *name;
-	int ok, val;
 
-	/* recurse in once to catch bad loops */
+	/*
+	 * recurse in once to catch bad loops,
+	 * bb->context is initialised to -1.
+	 */
 	if (bb->context > 0)
 		return 0;
-
 	bb->context++;
 
+	/*
+	 * We're starting with a completely new local list of contexts, so
+	 * initialise it according to what we got from the parent block.
+	 * That may use either the 'false' or the 'true' part of the context
+	 * for the conditional_context() attribute.
+	 */
 	FOR_EACH_PTR(ccl_in, c) {
 		if (in_false)
 			context_add(&combined, c->name, c->val_false, c->val_false);
@@ -133,76 +260,37 @@ static int check_bb_context(struct entrypoint *ep, struct basic_block *bb,
 			context_add(&combined, c->name, c->val, c->val);
 	} END_FOR_EACH_PTR(c);
 
+	/*
+	 * Now walk the instructions for this block, recursing into any
+	 * instructions that have children. We need to have the right
+	 * order so we cannot iterate bb->children instead.
+	 */
 	FOR_EACH_PTR(bb->insns, insn) {
-		if (!insn->bb)
-			continue;
 		switch (insn->opcode) {
 		case OP_INLINED_CALL:
 		case OP_CALL:
-			if (!insn->func || !insn->func->sym || insn->func->type != PSEUDO_SYM)
-				break;
-			FOR_EACH_PTR(insn->func->sym->ctype.contexts, ctx) {
-				name = context_name(ctx);
-				val = 0;
-
-				FOR_EACH_PTR(combined, c) {
-					if (strcmp(c->name, name) == 0) {
-						val = c->val;
-						break;
-					}
-				} END_FOR_EACH_PTR(c);
-
-				if (ctx->exact)
-					ok = ctx->in == val;
-				else
-					ok = ctx->in <= val;
-
-				if (!ok) {
-					const char *call = strdup(show_ident(insn->func->ident));
-					warning(insn->pos, "context problem in '%s' - function '%s' expected different context",
-						show_ident(ep->name->ident), call);
-					free((void *)call);
-					return -1;
-				}
-			} END_FOR_EACH_PTR (ctx);
+			if (handle_call(ep, bb, insn, combined))
+				return -1;
 			break;
 		case OP_CONTEXT:
-			val = 0;
-
-			name = unnamed_context;
-			if (insn->context_expr)
-				name = show_ident(insn->context_expr->symbol_name);
-
-			FOR_EACH_PTR(combined, c) {
-				if (strcmp(c->name, name) == 0) {
-					val = c->val;
-					break;
-				}
-			} END_FOR_EACH_PTR(c);
-
-			ok = insn->required <= val;
-
-			if (!ok) {
-				name = strdup(name);
-				imbalance(ep, insn->pos, name, "__context__ statement expected different lock context");
-				free((void *)name);
+			if (handle_context(ep, bb, insn, &combined))
 				return -1;
-			}
-
-			context_add(&combined, name, insn->increment, insn->inc_false);
 			break;
 		case OP_BR:
 			if (insn->bb_true)
-				if (check_bb_context(ep, insn->bb_true, combined, ccl_target, 0))
+				if (check_bb_context(ep, insn->bb_true,
+						     combined, ccl_target, 0))
 					return -1;
 			if (insn->bb_false)
-				if (check_bb_context(ep, insn->bb_false, combined, ccl_target, 1))
+				if (check_bb_context(ep, insn->bb_false,
+						     combined, ccl_target, 1))
 					return -1;
 			break;
 		case OP_SWITCH:
 		case OP_COMPUTEDGOTO:
 			FOR_EACH_PTR(insn->multijmp_list, mj) {
-				if (check_bb_context(ep, mj->target, combined, ccl_target, 0))
+				if (check_bb_context(ep, mj->target,
+					             combined, ccl_target, 0))
 					return -1;
 			} END_FOR_EACH_PTR(mj);
 			break;
@@ -212,16 +300,10 @@ static int check_bb_context(struct entrypoint *ep, struct basic_block *bb,
 	insn = last_instruction(bb->insns);
 	if (!insn)
 		return 0;
+
 	if (insn->opcode == OP_RET)
 		return context_list_check(ep, insn->pos, combined, ccl_target);
 
-	FOR_EACH_PTR(bb->insns, insn) {
-		if (!insn->bb)
-			continue;
-		switch (insn->opcode) {
-		}
-	} END_FOR_EACH_PTR(insn);
-
 	/* contents will be freed once we return out of recursion */
 	free_ptr_list(&combined);
 
diff --git a/validation/context-dynamic.c b/validation/context-dynamic.c
index e3bbb98..5e172f0 100644
--- a/validation/context-dynamic.c
+++ b/validation/context-dynamic.c
@@ -151,11 +151,21 @@ static int good_switch(void)
     r();
 }
 
+static void bad_lock1(void)
+{
+    r();
+    a();
+}
+
 /*
  * check-name: Check -Wcontext with lock trylocks
  *
  * check-error-start
-context-dynamic.c:83:6: warning: context problem in 'bad_trylock1' - function 'r' expected different context
-context-dynamic.c:133:6: warning: context problem in 'bad_trylock2' - function 'r' expected different context
+context-dynamic.c:83:6: warning: context problem in 'bad_trylock1': 'r' expected different context
+context-dynamic.c:83:6:    context 'A': wanted >= 1, got 0
+context-dynamic.c:133:6: warning: context problem in 'bad_trylock2': 'r' expected different context
+context-dynamic.c:133:6:    context 'A': wanted >= 1, got 0
+context-dynamic.c:156:6: warning: context problem in 'bad_lock1': 'r' expected different context
+context-dynamic.c:156:6:    context 'A': wanted >= 1, got 0
  * check-error-end
  */
diff --git a/validation/context-named.c b/validation/context-named.c
index 806d736..58310e9 100644
--- a/validation/context-named.c
+++ b/validation/context-named.c
@@ -501,29 +501,53 @@ static void good_mixed_with_if(void)
  * check-name: Check -Wcontext with lock names
  *
  * check-error-start
-context-named.c:86:3: warning: context imbalance in 'warn_lock1' - wrong count at exit (TEST)
-context-named.c:93:3: warning: context imbalance in 'warn_lock2' - wrong count at exit (TEST)
-context-named.c:100:3: warning: context imbalance in 'warn_lock3' - wrong count at exit (TEST)
-context-named.c:105:3: warning: context problem in 'warn_unlock1' - function 'r' expected different context
-context-named.c:112:3: warning: context problem in 'warn_unlock2' - function 'r' expected different context
-context-named.c:152:9: warning: context imbalance in 'warn_if1' - wrong count at exit (TEST)
-context-named.c:162:9: warning: context imbalance in 'warn_if2' - wrong count at exit (TEST)
-context-named.c:218:4: warning: context imbalance in 'warn_while1' - wrong count at exit (TEST)
-context-named.c:225:4: warning: context problem in 'warn_while2' - function 'r' expected different context
-context-named.c:235:4: warning: context imbalance in 'warn_while3' - wrong count at exit (TEST)
-context-named.c:295:5: warning: context imbalance in 'warn_goto1' - wrong count at exit (TEST)
-context-named.c:305:6: warning: context imbalance in 'warn_goto2' - wrong count at exit (TEST)
-context-named.c:315:6: warning: context problem in 'warn_goto3' - function 'r' expected different context
-context-named.c:321:7: warning: context imbalance in 'warn_multiple1' - wrong count at exit (TEST)
-context-named.c:327:6: warning: context imbalance in 'warn_multiple2' - wrong count at exit (TEST2)
-context-named.c:333:6: warning: context problem in 'warn_mixed1' - function 'r' expected different context
-context-named.c:343:6: warning: context problem in 'warn_mixed2' - function 'r' expected different context
-context-named.c:353:6: warning: context problem in 'warn_mixed3' - function 'r' expected different context
-context-named.c:364:6: warning: context imbalance in 'warn_mixed4' - wrong count at exit (TEST2)
-context-named.c:434:14: warning: context problem in 'warn_fn' - function 'need_lock' expected different context
-context-named.c:441:15: warning: context problem in 'warn_fn2' - function 'need_lock2' expected different context
-context-named.c:456:20: warning: context problem in 'warn_exact_fn1' - function 'need_lock_exact' expected different context
-context-named.c:464:20: warning: context problem in 'warn_exact_fn2' - function 'need_lock_exact' expected different context
-context-named.c:475:15: warning: context problem in 'warn_fn3' - function 'need_lock3' expected different context
+context-named.c:86:3: warning: context imbalance in 'warn_lock1': wrong count at exit
+context-named.c:86:3:    context 'TEST': wanted 0, got 1
+context-named.c:93:3: warning: context imbalance in 'warn_lock2': wrong count at exit
+context-named.c:93:3:    context 'TEST': wanted 0, got 1
+context-named.c:100:3: warning: context imbalance in 'warn_lock3': wrong count at exit
+context-named.c:100:3:    context 'TEST': wanted 0, got 1
+context-named.c:105:3: warning: context problem in 'warn_unlock1': 'r' expected different context
+context-named.c:105:3:    context 'TEST': wanted >= 1, got 0
+context-named.c:112:3: warning: context problem in 'warn_unlock2': 'r' expected different context
+context-named.c:112:3:    context 'TEST': wanted >= 1, got 0
+context-named.c:152:9: warning: context imbalance in 'warn_if1': wrong count at exit
+context-named.c:152:9:    context 'TEST': wanted 0, got 1
+context-named.c:162:9: warning: context imbalance in 'warn_if2': wrong count at exit
+context-named.c:162:9:    context 'TEST': wanted 0, got 1
+context-named.c:218:4: warning: context imbalance in 'warn_while1': wrong count at exit
+context-named.c:218:4:    context 'TEST': wanted 0, got 1
+context-named.c:225:4: warning: context problem in 'warn_while2': 'r' expected different context
+context-named.c:225:4:    context 'TEST': wanted >= 1, got 0
+context-named.c:235:4: warning: context imbalance in 'warn_while3': wrong count at exit
+context-named.c:235:4:    context 'TEST': wanted 0, got 1
+context-named.c:295:5: warning: context imbalance in 'warn_goto1': wrong count at exit
+context-named.c:295:5:    context 'TEST': wanted 0, got 1
+context-named.c:305:6: warning: context imbalance in 'warn_goto2': wrong count at exit
+context-named.c:305:6:    context 'TEST': wanted 0, got 1
+context-named.c:315:6: warning: context problem in 'warn_goto3': 'r' expected different context
+context-named.c:315:6:    context 'TEST': wanted >= 1, got 0
+context-named.c:321:7: warning: context imbalance in 'warn_multiple1': wrong count at exit
+context-named.c:321:7:    context 'TEST': wanted 0, got 1
+context-named.c:327:6: warning: context imbalance in 'warn_multiple2': wrong count at exit
+context-named.c:327:6:    context 'TEST2': wanted 0, got 1
+context-named.c:333:6: warning: context problem in 'warn_mixed1': 'r' expected different context
+context-named.c:333:6:    context 'TEST': wanted >= 1, got 0
+context-named.c:343:6: warning: context problem in 'warn_mixed2': 'r' expected different context
+context-named.c:343:6:    context 'TEST': wanted >= 1, got 0
+context-named.c:353:6: warning: context problem in 'warn_mixed3': 'r' expected different context
+context-named.c:353:6:    context 'TEST': wanted >= 1, got 0
+context-named.c:364:6: warning: context imbalance in 'warn_mixed4': wrong count at exit
+context-named.c:364:6:    context 'TEST2': wanted 0, got 1
+context-named.c:434:14: warning: context problem in 'warn_fn': 'need_lock' expected different context
+context-named.c:434:14:    context 'TEST': wanted >= 1, got 0
+context-named.c:441:15: warning: context problem in 'warn_fn2': 'need_lock2' expected different context
+context-named.c:441:15:    context 'TEST': wanted >= 1, got 0
+context-named.c:456:20: warning: context problem in 'warn_exact_fn1': 'need_lock_exact' expected different context
+context-named.c:456:20:    context 'TEST': wanted 1, got 2
+context-named.c:464:20: warning: context problem in 'warn_exact_fn2': 'need_lock_exact' expected different context
+context-named.c:464:20:    context 'TEST': wanted 1, got 0
+context-named.c:475:15: warning: context problem in 'warn_fn3': 'need_lock3' expected different context
+context-named.c:475:15:    context 'TEST': wanted >= 1, got 0
  * check-error-end
  */
diff --git a/validation/context-statement.c b/validation/context-statement.c
index ec26fef..fd79a6a 100644
--- a/validation/context-statement.c
+++ b/validation/context-statement.c
@@ -47,12 +47,23 @@ static void bad_macro2(void)
     m();
 }
 
+static void bad_macro3(void)
+{
+    r();
+    a();
+}
+
 /*
  * check-name: Check __context__ statement with required context
  *
  * check-error-start
-context-statement.c:16:8: warning: context imbalance in 'bad_arr' - unexpected unlock (LOCK)
-context-statement.c:38:5: warning: context imbalance in 'bad_macro1' - __context__ statement expected different lock context (LOCK)
-context-statement.c:47:5: warning: context imbalance in 'bad_macro2' - __context__ statement expected different lock context (LOCK)
+context-statement.c:16:8: warning: context imbalance in 'bad_arr': unexpected unlock
+context-statement.c:16:8:    context 'LOCK': wanted 0, got -1
+context-statement.c:38:5: warning: context imbalance in 'bad_macro1': __context__ statement expected different context
+context-statement.c:38:5:    context 'LOCK': wanted >= 1, got 0
+context-statement.c:47:5: warning: context imbalance in 'bad_macro2': __context__ statement expected different context
+context-statement.c:47:5:    context 'LOCK': wanted >= 1, got 0
+context-statement.c:53:5: warning: context imbalance in 'bad_macro3': __context__ statement expected different context
+context-statement.c:53:5:    context 'LOCK': wanted >= 0, got -1
  * check-error-end
  */
diff --git a/validation/context.c b/validation/context.c
index df337e5..4250e95 100644
--- a/validation/context.c
+++ b/validation/context.c
@@ -325,24 +325,84 @@ static void warn_odd_looping(void)
         r();
 }
 
+static void warn_huge_switch(void)
+{
+    a();
+
+    switch(condition) {
+    case 1:
+        r();
+        break;
+    case 2:
+        r();
+        break;
+    case 3:
+        r();
+        break;
+    case 4:
+        r();
+        break;
+    case 5:
+        r();
+        break;
+    case 11:
+        r();
+        break;
+    case 12:
+        r();
+        break;
+    case 13:
+        r();
+        break;
+    case 14:
+        r();
+    case 15:
+        r();
+        break;
+    case 16:
+        r();
+        break;
+    case 17:
+        r();
+        break;
+    }
+}
+
 /*
  * check-name: Check -Wcontext
  *
  * check-error-start
-context.c:71:3: warning: context imbalance in 'warn_lock1' - wrong count at exit
-context.c:78:3: warning: context imbalance in 'warn_lock2' - wrong count at exit
-context.c:85:3: warning: context imbalance in 'warn_lock3' - wrong count at exit
-context.c:90:3: warning: context problem in 'warn_unlock1' - function 'r' expected different context
-context.c:97:3: warning: context problem in 'warn_unlock2' - function 'r' expected different context
-context.c:137:9: warning: context imbalance in 'warn_if1' - wrong count at exit
-context.c:147:9: warning: context imbalance in 'warn_if2' - wrong count at exit
-context.c:203:4: warning: context imbalance in 'warn_while1' - wrong count at exit
-context.c:210:4: warning: context problem in 'warn_while2' - function 'r' expected different context
-context.c:220:4: warning: context imbalance in 'warn_while3' - wrong count at exit
-context.c:280:5: warning: context imbalance in 'warn_goto1' - wrong count at exit
-context.c:290:6: warning: context imbalance in 'warn_goto2' - wrong count at exit
-context.c:300:6: warning: context problem in 'warn_goto3' - function 'r' expected different context
-context.c:315:6: warning: context problem in 'warn_cond_lock1' - function 'r' expected different context
-context.c:325:10: warning: context problem in 'warn_odd_looping' - function 'r' expected different context
+context.c:71:3: warning: context imbalance in 'warn_lock1': wrong count at exit
+context.c:71:3:    default context: wanted 0, got 1
+context.c:78:3: warning: context imbalance in 'warn_lock2': wrong count at exit
+context.c:78:3:    default context: wanted 0, got 1
+context.c:85:3: warning: context imbalance in 'warn_lock3': wrong count at exit
+context.c:85:3:    default context: wanted 0, got 1
+context.c:90:3: warning: context problem in 'warn_unlock1': 'r' expected different context
+context.c:90:3:    default context: wanted >= 1, got 0
+context.c:97:3: warning: context problem in 'warn_unlock2': 'r' expected different context
+context.c:97:3:    default context: wanted >= 1, got 0
+context.c:137:9: warning: context imbalance in 'warn_if1': wrong count at exit
+context.c:137:9:    default context: wanted 0, got 1
+context.c:147:9: warning: context imbalance in 'warn_if2': wrong count at exit
+context.c:147:9:    default context: wanted 0, got 1
+context.c:203:4: warning: context imbalance in 'warn_while1': wrong count at exit
+context.c:203:4:    default context: wanted 0, got 1
+context.c:210:4: warning: context problem in 'warn_while2': 'r' expected different context
+context.c:210:4:    default context: wanted >= 1, got 0
+context.c:220:4: warning: context imbalance in 'warn_while3': wrong count at exit
+context.c:220:4:    default context: wanted 0, got 1
+context.c:280:5: warning: context imbalance in 'warn_goto1': wrong count at exit
+context.c:280:5:    default context: wanted 0, got 1
+context.c:290:6: warning: context imbalance in 'warn_goto2': wrong count at exit
+context.c:290:6:    default context: wanted 0, got 1
+context.c:300:6: warning: context problem in 'warn_goto3': 'r' expected different context
+context.c:300:6:    default context: wanted >= 1, got 0
+context.c:315:6: warning: context problem in 'warn_cond_lock1': 'r' expected different context
+context.c:315:6:    default context: wanted >= 1, got 0
+context.c:325:10: warning: context problem in 'warn_odd_looping': 'r' expected different context
+context.c:325:10:    default context: wanted >= 1, got 0
+context.c:360:10: warning: context problem in 'warn_huge_switch': 'r' expected different context
+context.c:360:10:    default context: wanted >= 1, got 0
  * check-error-end
  */