Currently we consider that each constant has itself as a base value. I.e "base(const) = const".
This introduces couple of problems when we are trying to avoid reporting constants in statepoint live sets:
1. When querying "base( phi(const1, const2) )" we will get "phi(const1, const2)" as a base pointer. Since
it's not a constant we will record it in a stack map. However on practice we don't want this to happen
(constant are never relocated).
2. base( phi(const, gc ptr) ) = phi( const, base(gc ptr) ). This particular case imposes challenge on our
runtime - we don't expect to see constant base pointers other than null. This problems can be avoided
by treating all constant as if they were derived from null pointer base. I.e in a first case we will
not include constant pointer in a stack map at all. In a second case we will get "phi(null, base(gc ptr))"
as a base pointer which is a lot more convenient.
Differential Revision: http://reviews.llvm.org/D20584
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270993 91177308-0d34-0410-b5e6-96231b3b80d8
Goal of this change is to guarantee stable ordering of the statepoint arguments and other
newly inserted values such as gc.relocates. Previously we had explicit sorting in a couple
of places. However for unnamed values ordering was partial and overall we didn't have any
strong invariant regarding it. This change switches all data structures to use SetVector's
and MapVector's which provide possibility for deterministic iteration over them.
Explicit sorting is now redundant and was removed.
Differential Revision: http://reviews.llvm.org/D19669
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268502 91177308-0d34-0410-b5e6-96231b3b80d8
This change reverts "246133 [RewriteStatepointsForGC] Reduce the number of new instructions for base pointers" and a follow on bugfix 12575.
As pointed out in pr25846, this code suffers from a memory corruption bug. Since I'm (empirically) not going to get back to this any time soon, simply reverting the problematic change is the right answer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261565 91177308-0d34-0410-b5e6-96231b3b80d8
The full diff for the test directory may be hard to read because of the
filename clash; so here's all that happened as far as the tests are
concerned:
```
cd test/Transforms/RewriteStatepointsForGC
git rm *ll
git mv deopt-bundles/* ./
rmdir deopt-bundles
find . -name '*.ll' | xargs gsed -i 's/-rs4gc-use-deopt-bundles //g'
```
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259129 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This patch changes gc.statepoint intrinsic's return type to token type instead of i32 type. Using token types could prevent LLVM to merge different gc.statepoint nodes into PHI nodes and cause further problems with gc relocations. The patch also changes the way on how gc.relocate and gc.result look for their corresponding gc.statepoint on unwind path. The current implementation uses the selector value extracted from a { i8*, i32 } landingpad as a hook to find the gc.statepoint, while the patch directly uses a token type landingpad (http://reviews.llvm.org/D15405) to find the gc.statepoint.
Reviewers: sanjoy, JosephTremoulet, pgavlin, igor-laevsky, mjacob
Subscribers: reames, mjacob, sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D15662
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256443 91177308-0d34-0410-b5e6-96231b3b80d8
This change is simply enhancing the existing inference algorithm to handle insertelement instructions by conservatively inserting a new instruction to propagate the vector of associated base pointers. In the process, I'm ripping out the peephole optimizations which mostly helped cover the fact this hadn't been done.
Note that most of the newly inserted nodes will be nearly immediately removed by the post insertion optimization pass introduced in 246718. Arguably, we should be trying harder to avoid the malloc traffic here, but I'd rather get the code correct, then worry about compile time.
Unlike previous extensions of the algorithm to handle more case, I discovered the existing code was causing miscompiles in some cases. In particular, we had an implicit assumption that the peephole covered *all* insert element instructions, so if we had a value directly based on a insert element the peephole didn't cover, we proceeded as if it were a base anyways. Not good. I believe we had the same issue with shufflevector which is why I adjusted the predicate for them as well.
Differential Revision: http://reviews.llvm.org/D12583
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247210 91177308-0d34-0410-b5e6-96231b3b80d8
When computing base pointers, we introduce new instructions to propagate the base of existing instructions which might not be bases. However, the algorithm doesn't make any effort to recognize when the new instruction to be inserted is the same as an existing one already in the IR. Since this is happening immediately before rewriting, we don't really have a chance to fix it after the pass runs without teaching loop passes about statepoints.
I'm really not thrilled with this patch. I've rewritten it 4 different ways now, but this is the best I've come up with. The case where the new instruction is just the original base defining value could be merged into the existing algorithm with some complexity. The problem is that we might have something like an extractelement from a phi of two vectors. It may be trivially obvious that the base of the 0th element is an existing instruction, but I can't see how to make the algorithm itself figure that out. Thus, I resort to the call to SimplifyInstruction instead.
Note that we can only adjust the instructions we've inserted ourselves. The live sets are still being tracked in side structures at this point in the code. We can't easily muck with instructions which might be in them. Long term, I'm really thinking we need to materialize the live pointer sets explicitly in the IR somehow rather than using side structures to track them.
Differential Revision: http://reviews.llvm.org/D12004
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246133 91177308-0d34-0410-b5e6-96231b3b80d8
When rewriting the IR such that base pointers are available for every live pointer, we potentially need to duplicate instructions to propagate the base. The original code had only handled PHI and Select under the belief those were the only instructions which would need duplicated. When I added support for vector instructions, I'd added a collection of hacks for ExtractElement which caught most of the common cases. Of course, I then found the one test case my hacks couldn't cover. :)
This change removes all of the early hacks for extract element. By defining extractelement as a BDV (rather than trying to look through it), we can extend the rewriting algorithm to duplicate the extract as needed. Note that a couple of peephole optimizations were left in for the moment, because while we now handle extractelement as a first class citizen, we're not yet handling insertelement. That change will follow in the near future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244808 91177308-0d34-0410-b5e6-96231b3b80d8
