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[PATCH v5, middle end]: Committed: Fix PR 37908, thinko with atomic NAND operation


On Sun, Nov 16, 2008 at 8:18 PM, Mark Mitchell <mark@codesourcery.com> wrote:

>> However, I'm not sure I understood the reason to disable the note. The
>> note can be IMO considered as "less than a warning", just a heads-up
>> that something has been changed that requires a bit of attention.
>
> See all the various threads on "fine-grained warning control" over the
> years.
>
> Once you go through and audit your code to make sure that you're using
> the builtin in the way that it now behaves, the warning is just noise.
> You want the signal-to-noise ratio to be high.  So, you want a way to
> turn it off.  Otherwise, every compilation of your project results in
> the same pointless note.
>
> In general, it should be possible to disable all non-errors.  That's "in
> general"; there are exceptions.

Attached is the patch that was commited to SVN. I didn't want to add a
message to the note itself, since the way to disable this note was
added to the documentation.

2008-11-17  Uros Bizjak  <ubizjak@gmail.com>

	PR middle-end/37908
	* optabs.c (expand_sync_operation): Properly handle NAND case
	by calculating ~(t1 & val) instead of (~t1 & val).
	* builtins.c (expand_builtin_sync_operation): Warn for changed
	semantics in NAND builtins.
	* c.opt (Wsync-nand): New warning option.  Describe -Wsync-nand.
	
	* doc/invoke.texi (Warning options): Add Wsync-nand.
	* doc/extend.texi (Atomic Builtins) [__sync_fetch_and_nand]: Correct
	__sync_fetch_and_nand builtin operation in the example.  Add a note
	about changed semantics in GCC 4.4.
	[__sync_nand_and_fetch]: Correct __sync_nand_and_fetch builtin
	operation in the example.  Add a note about changed semantics in
	GCC 4.4.

testsuite/ChangeLog:

2008-11-17  Uros Bizjak  <ubizjak@gmail.com>

	PR middle-end/37908
	* gcc.dg/pr37908.c: New test.
	* gcc.dg/ia64-sync-1.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_si, init_di): Change init value for __sync_fetch_and_nand to -1.
	(test_si, test_di): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/ia64-sync-2.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_noret_si, init_noret_di): Change init value for
	__sync_fetch_and_nand to -1.
	(init_noret_si, init_noret_di): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/sync-2.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_qi, init_qi): Change init value for __sync_fetch_and_nand to -1.
	(init_hi, init_hi): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/sync-3.c: Copy from sync-2.c instead of including
	the c source file.
	* gcc.c-torture/compile/sync-1.c: Add dg-message to look for the
	warning about changed semantics of NAND builtin.
	* gcc.c-torture/compile/sync-2.c: Ditto.
	* gcc.c-torture/compile/sync-3.c: Ditto.

Patch was regression tested and bootstrapped on i686-pc-linux-gnu and
x86_64-pc-linux-gnu {,-m32}.

Uros.

Attachment: p.diff.txt
Description: Text document


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