Summary:
EHPad BB are not entered the classic way and therefor do not need to be placed after their predecessors. This patch make sure EHPad BB are not chosen amongst successors to form chains, and are selected as last resort when selecting the best candidate.
EHPad are scheduled in reverse probability order in order to have them flow into each others naturally.
Reviewers: chandlerc, majnemer, rafael, MatzeB, escha, silvas
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D17625
llvm-svn: 265726
SimplifyCFG allows tail merging with code which terminates in
unreachable which, in turn, makes it possible for an invoke to end up in
a funclet which it was not originally part of.
Using operand bundles on invokes allows us to determine whether or not
an invoke was part of a funclet in the source program.
Furthermore, it allows us to unambiguously answer questions about the
legality of inlining into call sites which the personality may have
trouble with.
Differential Revision: http://reviews.llvm.org/D15517
llvm-svn: 255674
While we have successfully implemented a funclet-oriented EH scheme on
top of LLVM IR, our scheme has some notable deficiencies:
- catchendpad and cleanupendpad are necessary in the current design
but they are difficult to explain to others, even to seasoned LLVM
experts.
- catchendpad and cleanupendpad are optimization barriers. They cannot
be split and force all potentially throwing call-sites to be invokes.
This has a noticable effect on the quality of our code generation.
- catchpad, while similar in some aspects to invoke, is fairly awkward.
It is unsplittable, starts a funclet, and has control flow to other
funclets.
- The nesting relationship between funclets is currently a property of
control flow edges. Because of this, we are forced to carefully
analyze the flow graph to see if there might potentially exist illegal
nesting among funclets. While we have logic to clone funclets when
they are illegally nested, it would be nicer if we had a
representation which forbade them upfront.
Let's clean this up a bit by doing the following:
- Instead, make catchpad more like cleanuppad and landingpad: no control
flow, just a bunch of simple operands; catchpad would be splittable.
- Introduce catchswitch, a control flow instruction designed to model
the constraints of funclet oriented EH.
- Make funclet scoping explicit by having funclet instructions consume
the token produced by the funclet which contains them.
- Remove catchendpad and cleanupendpad. Their presence can be inferred
implicitly using coloring information.
N.B. The state numbering code for the CLR has been updated but the
veracity of it's output cannot be spoken for. An expert should take a
look to make sure the results are reasonable.
Reviewers: rnk, JosephTremoulet, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D15139
llvm-svn: 255422
When lowering invoke statement, all unwind destinations are directly added as successors of call site block, and the weight of those new edges are not assigned properly. Actually, default weight 16 are used for those edges. This patch calculates the proper edge weights for those edges when collecting all unwind destinations.
Differential revision: http://reviews.llvm.org/D13354
llvm-svn: 250119
Also Fix a buglet where SEH tables had ranges that spanned funclets.
The remaining tests using the old landingpad IR are preparation tests,
and will be deleted along with the old preparation.
llvm-svn: 249917
The incoming EBP value established by the runtime is actually a pointer
to the end of the EH registration object, and not the true parent
function frame pointer. Clang doesn't need llvm.x86.seh.exceptioninfo
anymore because we know that the exception info pointer is at a fixed
offset from this incoming EBP.
The llvm.x86.seh.recoverfp intrinsic takes an EBP value provided by the
EH runtime and returns a pointer that is usable with llvm.framerecover.
The llvm.x86.seh.restoreframe intrinsic is inserted by the 32-bit
specific preparation pass in blocks targetted by the EH runtime. It
re-establishes any physical registers used by the parent function to
address the stack, such as the frame, base, and stack pointers.
Neither of these intrinsics correctly handle stack realignment prologues
yet, but it's possible to add that later.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D10848
llvm-svn: 241125
The personality routine currently lives in the LandingPadInst.
This isn't desirable because:
- All LandingPadInsts in the same function must have the same
personality routine. This means that each LandingPadInst beyond the
first has an operand which produces no additional information.
- There is ongoing work to introduce EH IR constructs other than
LandingPadInst. Moving the personality routine off of any one
particular Instruction and onto the parent function seems a lot better
than have N different places a personality function can sneak onto an
exceptional function.
Differential Revision: http://reviews.llvm.org/D10429
llvm-svn: 239940
We were putting them in the filter field, which is correct for 64-bit
but wrong for 32-bit.
Also switch the order of scope table entry emission so outermost entries
are emitted first, and fix an obvious state assignment bug.
llvm-svn: 239574
This intrinsic is like framerecover plus a load. It recovers the EH
registration stack allocation from the parent frame and loads the
exception information field out of it, giving back a pointer to an
EXCEPTION_POINTERS struct. It's designed for clang to use in SEH filter
expressions instead of accessing the EXCEPTION_POINTERS parameter that
is available on x64.
This required a minor change to MC to allow defining a label variable to
another absolute framerecover label variable.
llvm-svn: 239567
This gets all the handler info through to the asm printer and we can
look at the .xdata tables now. I've convinced one small catch-all test
case to work, but other than that, it would be a stretch to say this is
functional.
The state numbering algorithm avoids doing any scope reconstruction as
we do for C++ to simplify the implementation.
llvm-svn: 239433
Amaury Sechet