Hi David,
Ok, will do.
I am currently working on another revision that checks TLS alignment when it is
instantiated via a template parameter.
Like this.
/***************************************/
template <int N>
struct S {
static int __thread __attribute__((aligned(N))) x;
};
S<64> x_inst; // expected-error{{alignment (64) of thread-local variable}}
/***************************************/
I expect to have the 5th iteration up next Tuesday.
Sincerely,
Charles Li
From: David Majnemer [mailto:[email protected]]
Sent: Wednesday, May 27, 2015 3:24 PM
To: Li, Charles
Cc: [email protected]; Domizioli, Dario; Richard Smith
Subject: Re: Proposed patch (4th revision) adds TLS Max Alignment diagnostic
One of your run lines doesn't do anything:
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsyntax-only %s
Please remove it.
On Fri, May 1, 2015 at 12:10 PM, Li, Charles
<[email protected]<mailto:[email protected]>> wrote:
Hi David,
I have revised the TLS Max Align patch taken into account of all the reviews
from you and Richard.
I would very much appreciate another code review.
Also Richard has the following question for you from the previous email (review
for the 3rd revision of the patch). I would also appreciate your input.
> David: You have the most recent state on this -- can you check this is doing
> the right set of checks to find a dependent alignment? (Also, are we doing
> this check elsewhere? Should we move this check to ASTContext?)
Thank you,
Charles Li
From: Li, Charles
Sent: Thursday, April 30, 2015 6:48 PM
To: [email protected]<mailto:[email protected]>; 'Richard Smith';
David Majnemer
Cc: Domizioli, Dario
Subject: RE: Proposed patch (4th revision) adds TLS Max Alignment diagnostic
Hi Richard,
Thank you very much for pointing out all the intricacies I was not aware of.
Both points have been addressed.
1. Dependent type check has been moved into the function
hasDependentAlignment
2. The previous comment
/// hasDependentAlignment - determines if a variable's alignment is dependent
has been changed to
/// \brief Determines if a variable's alignment is dependent.
Please let me know if there are any more bugs. I very much appreciate it.
Sincerely,
Charles Li
From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On
Behalf Of Richard Smith
Sent: Thursday, April 30, 2015 4:43 PM
To: Li, Charles; David Majnemer
Cc: [email protected]<mailto:[email protected]>; Domizioli, Dario
Subject: Re: Proposed patch (3rd revision) adds TLS Max Alignment diagnostic
Looks OK to me, but I'd prefer the VD->getType()->isDependentType() check to be
inside hasDependentAlignment, since a variable with a dependent type is assumed
to have a dependent alignment.
David: You have the most recent state on this -- can you check this is doing
the right set of checks to find a dependent alignment? (Also, are we doing this
check elsewhere? Should we move this check to ASTContext?)
One totally trivial thing to fix before commit:
+/// hasDependentAlignment - determines if a variable's alignment is dependent
We prefer to use \brief instead of repeating the function name in new code.
Thanks!
On Thu, Apr 30, 2015 at 4:21 PM, Li, Charles
<[email protected]<mailto:[email protected]>> wrote:
Hi Everyone,
I am back again with the 3rd revision of the patch which adds an error
diagnostic for when TLS variables exceed maximum TLS alignment.
This patch fixed 4 shortcomings.
1. Dependent alignment check has been spun off into a static function
called hasDependentAlignment
2. Redundant code on checking for reference type and getting its pointee
type has been removed.
3. Improved diagnostic to show the requested alignment of the variable
4. Added a Run line in the test to ensure x86_64-linux-gnu works the same
as before.
Many thanks to the peer reviewers out there.
Sincerely,
Charles Li
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]<mailto:[email protected]>] On Behalf Of Richard Smith
Sent: Thursday, April 16, 2015 4:41 PM
To: Li, Charles
Cc: [email protected]<mailto:[email protected]>; Domizioli, Dario
Subject: Re: Proposed patch (2nd revision) adds TLS Max Alignment diagnostic
+ if (const unsigned MaxAlign = Context.getTargetInfo().getMaxTLSAlign()) {
+ for (auto *I : VD->specific_attrs<AlignedAttr>()) {
+ if (I->isAlignmentDependent())
+ return;
Do not return here. You're in the middle of a function that does a bunch of
other checks after this point. Perhaps factor out a static
hasDependentAlignment helper function?
+ }
+
+ if (VD->getTLSKind()) {
+ QualType T = VD->getType();
+ if (const ReferenceType *RT = T->getAs<ReferenceType>())
+ T = Context.getPointerType(RT->getPointeeType());
This code is redundant. The only place you use T is when you detect whether
it's dependent:
+ if (!T->isDependentType()) {
... which is unaffected by whether it's a pointer or a reference type.
+def err_tls_var_aligned_over_maximum : Error<
+ "alignment of thread-local variable %0 is greater than the maximum supported
"
+ "alignment (%1) for a thread-local variable on this target">;
Maybe include the requested alignment of the variable in this error?
+// RUN: %clang_cc1 -triple x86_64-scei-ps4 -fsyntax-only -verify %s
Please also add something like
// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsyntax-only %s
... to verify that we don't emit any diagnostics for the case where we don't
have an alignment limit.
On Wed, Apr 15, 2015 at 4:04 PM, Li, Charles
<[email protected]<mailto:[email protected]>> wrote:
Hi Everyone,
We have updated the proposed patch which adds an error diagnostic for when TLS
variables exceed maximum TLS alignment.
This update takes care of the case where alignment is dependent. It also
removed the unnecessary getBaseElementType() call.
Sincerely,
Charles Li
From: Li, Charles
Sent: Friday, April 03, 2015 3:21 PM
To: 'David Majnemer'
Cc: [email protected]<mailto:[email protected]>
Subject: RE: Proposed patch adds TLS Max Alignment diagnostic
Hi David,
Oops, we didn’t think of the case where the alignment could be a template
parameter.
I currently don’t have a clue to fix this.
Any hint would be greatly welcome.
On why we used BaseT instead of T.
I think we originally added
QualType BaseT = Context.getBaseElementType(T);
Just be to conservative as we don’t fully understand how LLVM’s type system
when it comes to templates.
I have re-ran clang replacing BaseT with T and did not notice any regressions.
So I will take out BaseT for the next revision of the patch.
Cheers,
Charles Li
From: David Majnemer [mailto:[email protected]]
Sent: Wednesday, April 01, 2015 7:08 PM
To: Li, Charles
Cc: [email protected]<mailto:[email protected]>
Subject: Re: Proposed patch adds TLS Max Alignment diagnostic
Hi Charles,
Your patch doesn't handle cases where the alignment is dependent, getDeclAlign
doesn't want to be called in such cases:
template <int N>
struct S {
static int __thread __attribute__((aligned(N))) x;
};
Also, why do you use BaseT->isDependentType() instead of T->isDependentType()?
On Wed, Apr 1, 2015 at 4:57 PM, Li, Charles
<[email protected]<mailto:[email protected]>> wrote:
Hi Clang developers,
We here at Sony PlayStation have a proposed patch which adds an error
diagnostic for when TLS variables exceed maximum TLS alignment.
Please note this patch does not affect normal maximum alignments.
This TLS maximum alignment check is currently only turned on for PS4 but could
potentially be used for other platforms.
Sincerely,
Charles Li
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