From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: linux-sparse@vger.kernel.org
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: [PATCH 3/3] dereference of a function is a no-op
Date: Thu, 21 Dec 2017 01:19:15 +0100 [thread overview]
Message-ID: <20171221001915.57047-4-luc.vanoostenryck@gmail.com> (raw)
In-Reply-To: <20171221001915.57047-1-luc.vanoostenryck@gmail.com>
For the '*' operator and functions, the C standard says:
"If the operand points to a function, the result is a
function designator; ... If the operand has type
‘pointer to type’, the result has type ‘type’".
but also (C11 6.3.2.1p4):
"(except with 'sizeof' ...) a function designator with type
‘function returning type’ is converted to an expression
that has type ‘pointer to function returning type’".
This means that in dereferencement of a function-designator is
a no-op since the resulting expression is immediately back converted
to a pointer to the function.
The change effectively drop any dereferencement of function types
during their evaluation.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
evaluate.c | 3 +++
validation/function-pointer-type.c | 1 -
validation/linear/call-builtin.c | 1 -
validation/linear/call-direct.c | 1 -
validation/linear/call-indirect.c | 1 -
validation/linear/call-inline.c | 1 -
validation/sizeof-function.c | 1 -
7 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/evaluate.c b/evaluate.c
index e6dbe3d8d..840f98d3e 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -1782,6 +1782,9 @@ static struct symbol *evaluate_dereference(struct expression *expr)
default:
expression_error(expr, "cannot dereference this type");
return NULL;
+ case SYM_FN:
+ *expr = *op;
+ return expr->ctype;
case SYM_PTR:
node = alloc_symbol(expr->pos, SYM_NODE);
node->ctype.modifiers = target->ctype.modifiers & MOD_SPECIFIER;
diff --git a/validation/function-pointer-type.c b/validation/function-pointer-type.c
index cb1f59b2a..ebc4007ba 100644
--- a/validation/function-pointer-type.c
+++ b/validation/function-pointer-type.c
@@ -9,5 +9,4 @@ void f3(void) { int (*f)(void); f = ***fun; } // C99,C11 6.5.3.2p4
/*
* check-name: type of function pointers
* check-command: sparse -Wno-decl $file
- * check-known-to-fail
*/
diff --git a/validation/linear/call-builtin.c b/validation/linear/call-builtin.c
index b0261e992..b15113593 100644
--- a/validation/linear/call-builtin.c
+++ b/validation/linear/call-builtin.c
@@ -10,7 +10,6 @@ u32 f3(u32 a) { return (***__builtin_popcount)(a); } // C99,C11 6.5.3.2p4
/*
* check-name: builtin calls
* check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
*
* check-output-ignore
* check-output-excludes: load
diff --git a/validation/linear/call-direct.c b/validation/linear/call-direct.c
index 176bfe229..52f86306b 100644
--- a/validation/linear/call-direct.c
+++ b/validation/linear/call-direct.c
@@ -10,7 +10,6 @@ int f3(void) { return (***fun)(); } // C99,C11 6.5.3.2p4
/*
* check-name: direct calls
* check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
*
* check-output-ignore
* check-output-excludes: load
diff --git a/validation/linear/call-indirect.c b/validation/linear/call-indirect.c
index d8797b024..1275910c4 100644
--- a/validation/linear/call-indirect.c
+++ b/validation/linear/call-indirect.c
@@ -8,7 +8,6 @@ int g3(int (*fun)(void)) { return (***fun)(); } // C99,C11 6.5.3.2p4
/*
* check-name: indirect calls
* check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
*
* check-output-ignore
* check-output-excludes: load
diff --git a/validation/linear/call-inline.c b/validation/linear/call-inline.c
index d931a3cba..a33f0a1c8 100644
--- a/validation/linear/call-inline.c
+++ b/validation/linear/call-inline.c
@@ -10,7 +10,6 @@ int i3(void) { return (***fun)(); } // C99,C11 6.5.3.2p4
/*
* check-name: inline calls
* check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
*
* check-output-ignore
* check-output-excludes: load
diff --git a/validation/sizeof-function.c b/validation/sizeof-function.c
index 20c795e94..27d535d4e 100644
--- a/validation/sizeof-function.c
+++ b/validation/sizeof-function.c
@@ -36,7 +36,6 @@ int test(void)
/*
* check-name: sizeof-function
* check-command: sparse -Wno-decl $file
- * check-known-to-fail
*
* check-error-start
sizeof-function.c:22:14: warning: expression using sizeof on a function
--
2.15.0
prev parent reply other threads:[~2017-12-21 0:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-21 0:19 [PATCH 0/3] multiple dereference in function calls Luc Van Oostenryck
2017-12-21 0:19 ` [PATCH 1/3] add testcases for multiple deref of calls Luc Van Oostenryck
2017-12-21 0:19 ` [PATCH 2/3] avoid unneeded alloc on error path Luc Van Oostenryck
2017-12-21 0:19 ` Luc Van Oostenryck [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171221001915.57047-4-luc.vanoostenryck@gmail.com \
--to=luc.vanoostenryck@gmail.com \
--cc=linux-sparse@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).