JIT: refactor escape analysis to be more bv-centric #115213
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
Make the "bv index" the primary concept for computations; translate from local var nums to their indices when needed. Allocate all the connection BVs at once, since the connection matrix will now have a dense set of entries. This is prep work for tracking fields of stack allocatable objects, where we will introduce new classes of things tracked by the connection graph.
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Pull Request Overview
This PR refactors the escape analysis in the JIT to focus on bitvector (bv) indices rather than local variable numbers. Key changes include renaming pseudo-local variables to pseudo-indices, replacing HasIndex with IsTrackedLocal in escape checks, and introducing new index-based functions for stack allocation analysis.
Comments suppressed due to low confidence (1)
src/coreclr/jit/objectalloc.h:187
- The parameter name 'lclNum' in MarkIndexAsEscaping is inconsistent with other index-based functions; consider renaming it to 'index' for clarity.
void MarkIndexAsEscaping(unsigned int lclNum);
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PTAL @dotnet/jit-contrib No diffs. Likely somewhat tedious to review. Quite a bit of renaming (eg "pseudo var/local" - > "pseudo"), and trying to consistently use BV indices to describe non-local things, and to use Small TP win as we no longer repeatedly translate back and forth from local to index, eg in I reran this because of some infra issues, so the diff report has duplicated sections. |
| @@ -360,9 +373,9 @@ void ObjectAllocator::PrepareAnalysis() | |||
| // | |||
| // If conditional escape analysis is enabled, we reserve the range [N...N+M-1] | |||
| // for locals allocated during the conditional escape analysis expansions, | |||
| // where N is the maximum number of pseudo-vars. | |||
| // where N is the maximum number of pseudos. | |||
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Did you mean M?
| // where N is the maximum number of pseudos. | |
| // where M is the maximum number of pseudos. |
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Yeah. I will fix that in a subsequent PR, if there isn't any other feedback here.
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@dotnet/jit-contrib ping |
| // | ||
| BitVec pseudoLocalAdjacencies = m_ConnGraphAdjacencyMatrix[LocalToIndex(pseudoLocal)]; | ||
| BitVec PseudoAdjacencies = m_ConnGraphAdjacencyMatrix[pseudoIndex]; |
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Will fix this in the next stage...
No limits right now (other than implicitly limited by the number of escape-tracked locals). I can add something similar to the limit we have for regular tracked locals. |
Make the "bv index" the primary concept for computations; translate
from local var nums to their indices when needed.
Allocate all the connection BVs at once, since the connection matrix
will now have a dense set of entries.
This is prep work for tracking fields of stack allocatable objects,
where we will introduce new classes of things tracked by the
connection graph.