PR34351: Please get us the "volatile register" warning back

PR34351: Please get us the "volatile register" warning back

[Manuel López-Ibáñez]

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This patch enables -Wvolatile-register-var with -Wall fixing PR34351.

Bootstrapped and regression tested on x86_64-unknown-linux-gnu.

OK for 4.4?

Manuel.


2008-02-24  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

  PR 34351
  * doc/invoke.texi (-Wall): Add -Wvolatile-register-var.
  * c-opts.c (c_common_handle_option): Wall enables Wvolatile-register-var.
  * common.opt: Move Wvolatile-register-var to...
  * c.opt: ...here.

testsuite/
   * gcc.dg/pr34351.c: New.

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Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 132166)
+++ gcc/doc/invoke.texi	(working copy)
@@ -2670,10 +2670,11 @@ Options} and @ref{Objective-C and Object
 -Wunknown-pragmas  @gol
 -Wunused-function  @gol
 -Wunused-label     @gol
 -Wunused-value     @gol
 -Wunused-variable  @gol
+-Wvolatile-register-var @gol
 }
 
 Note that some warning flags are not implied by @option{-Wall}.  Some of
 them warn about constructions that users generally do not consider
 questionable, but which occasionally you might wish to check for;
@@ -3999,11 +4000,12 @@ the variable length array.
 @item -Wvolatile-register-var
 @opindex Wvolatile-register-var
 @opindex Wno-volatile-register-var
 Warn if a register variable is declared volatile.  The volatile
 modifier does not inhibit all optimizations that may eliminate reads
-and/or writes to register variables.
+and/or writes to register variables.  This warning is enabled by
+@option{-Wall}.
 
 @item -Wdisabled-optimization
 @opindex Wdisabled-optimization
 @opindex Wno-disabled-optimization
 Warn if a requested optimization pass is disabled.  This warning does
Index: gcc/testsuite/gcc.dg/pr34351.c
===================================================================
--- gcc/testsuite/gcc.dg/pr34351.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr34351.c	(revision 0)
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+register int * volatile x asm ("r13"); /* { dg-warning "optimization may eliminate reads and/or writes to register variables" } */
Index: gcc/c.opt
===================================================================
--- gcc/c.opt	(revision 132166)
+++ gcc/c.opt	(working copy)
@@ -467,10 +467,14 @@ Do not warn about using variadic macros 
 
 Wvla
 C ObjC C++ ObjC++ Var(warn_vla) Init(-1) Warning
 Warn if a variable length array is used
 
+Wvolatile-register-var
+C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning
+Warn when a register variable is declared volatile
+
 Wwrite-strings
 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
 In C++, nonzero means warn about deprecated conversion from string literals to `char *'.  In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
 
 Wpointer-sign
Index: gcc/c-opts.c
===================================================================
--- gcc/c-opts.c	(revision 132166)
+++ gcc/c-opts.c	(working copy)
@@ -405,10 +405,11 @@ c_common_handle_option (size_t scode, co
 	set_Wstrict_aliasing (value);
       warn_address = value;
       if (warn_strict_overflow == -1)
 	warn_strict_overflow = value;
       warn_array_bounds = value;
+      warn_volatile_register_var = value;
 
       /* Only warn about unknown pragmas that are not in system
 	 headers.  */
       warn_unknown_pragmas = value;
 
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 132166)
+++ gcc/common.opt	(working copy)
@@ -212,14 +212,10 @@ Warn when an expression value is unused
 
 Wunused-variable
 Common Var(warn_unused_variable) Warning
 Warn when a variable is unused
 
-Wvolatile-register-var
-Common Var(warn_register_var) Warning
-Warn when a register variable is declared volatile
-
 Wcoverage-mismatch
 Common RejectNegative Var(warn_coverage_mismatch) Warning
 Warn instead of error in case profiles in -fprofile-use do not match
 
 aux-info

Re: PR34351: Please get us the "volatile register" warning back

[Mark Mitchell]

Manuel López-Ibáñez wrote:

> 2008-02-24  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
> 
>   PR 34351
>   * doc/invoke.texi (-Wall): Add -Wvolatile-register-var.
>   * c-opts.c (c_common_handle_option): Wall enables Wvolatile-register-var.
>   * common.opt: Move Wvolatile-register-var to...
>   * c.opt: ...here.
> 
> testsuite/
>    * gcc.dg/pr34351.c: New.

OK.

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713

Re: PR34351: Please get us the "volatile register" warning back

[H.J. Lu]

The testcase is invalid on targets where r13 isn't a valid register:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35382


H.J.
On Sat, Feb 23, 2008 at 6:13 PM, Manuel López-Ibáñez
<lopezibanez@gmail.com> wrote:
> This patch enables -Wvolatile-register-var with -Wall fixing PR34351.
>
>  Bootstrapped and regression tested on x86_64-unknown-linux-gnu.
>
>  OK for 4.4?
>
>  Manuel.
>
>
>  2008-02-24  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
>
>   PR 34351
>   * doc/invoke.texi (-Wall): Add -Wvolatile-register-var.
>   * c-opts.c (c_common_handle_option): Wall enables Wvolatile-register-var.
>   * common.opt: Move Wvolatile-register-var to...
>   * c.opt: ...here.
>
>  testsuite/
>    * gcc.dg/pr34351.c: New.
>