tree 26805de8a52d8a63aaa5c2161640e5b6e8e6a910
parent f005bd5a3eded7dffe90e6fb2e7ea12db631fe21
author Ryan Macnak <rmacnak@google.com> 1560376613 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1560376613 +0000

[vm, compiler] Specialize unoptimized monomorphic and megamorphic calls.

dart-bytecode, arm64:            +4.742% geomean
dart-bytecode-jit-unopt, arm64: +12.73% geomean
dart2js-compile, x64:            +3.635% geomean

In the polymorphic and unlinked cases, call to a stub the does a linear scan against an ICData.

In the monomorphic case, call to a prologue of the expected target function that checks the expected receiver class. There is additional indirection in the JIT version compared to the AOT version to also tick a usage counter so the inliner can make good decisions.

In the megamorphic case, call to a stub that does a hash table lookup against a MegamorphicCache.

Megamorphic call sites face a loss of precision in usage counts. The call site count is not recorded and the usage counter of the target function is used as an approximation.

Monomorphic and megamorphic calls sites are reset to the polymorphic/unlinked state on hot reload.

Monomorphic and megamorphic calls sites do not check the stepping state, so they are reset to the polymorphic/unlinked state when stepping begins and disabled.

Back-edges now increment the usage counter in addition to checking it. This ensures function with loops containing monomorphic calls will eventually cross the optimization threshold.

Fixed backwards use of kMonomorphicEntryOffset and kPolymorphicEntryOffset.

Fixed C stack overflow when bouncing between the KBC interpreter and a simulator.

Bug: https://github.com/dart-lang/sdk/issues/26780
Bug: https://github.com/dart-lang/sdk/issues/36409
Bug: https://github.com/dart-lang/sdk/issues/36731
Change-Id: I78a49cccd962703a459288e71ce246ed845df474
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/102820
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>