This is a Dart-tailored implementation of the "row-displacement
dispatch table" technique for closed-world instance calls:
All interface targets in the program are grouped into selectors such
that all targets that could potentially be called from the same call
site have the same selector (currently just grouped by name).
Each selector is assigned a selector offset such that offset + classid
is unique for all selector/classid combinations where the class
implements the selector.
At every instance call site that has an interface target (i.e. where
the static type of the receiver is not dynamic), the selector offset +
receiver classid is computed and used as index into a global table of
entry points.
If the receiver can be null (as determined by the front-end TFA and the
VM type propagation), a null check is inserted before the call.
An arguments descriptor is provided (only) for selectors that need it
(those which have type parameters or optional/named parameters).
The dispatch table calls don't need the monomorphic entry code, so for
functions that are only called via dispatch table calls (i.e. never
called dynamically), the monomorphic entry code is left out.
Some future improvements to the table dispatch implementation are
mentioned in https://github.com/dart-lang/sdk/issues/40188
The table dispatch flag is disabled by default in this commit. A
separate commit enables the flag.
Change-Id: Ic2911742b4a2c9a8d3bc7df60605454cbe4c0714
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/126648
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Metadata is no longer written ahead of all nodes. Instead, metadata for
each node is written in the same context as the node itself (into a separate
buffer). This allows metadata to contain (serialize) arbitrary nodes
(for example, arbitrary DartTypes) and use serialization context of parent
nodes (such as declared type parameters).
However, with this change metadata looses the ability to reference
arbitrary AST nodes. This ability was overly restricted and had no
practical uses. (It was not possible to reference nodes which are not
reachable from root Component. As a consequence, it was not possible to
write references to arbitrary DartTypes.)
This change aligns the serialization capabilities of metadata with
how kernel AST nodes are serialized.
Change-Id: I027299a33b599b62572eccd4aa7083ad1dd2b3b3
Reviewed-on: https://dart-review.googlesource.com/54481
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
This relands 75a9579ea0.
The approach works as follows:
Step 1: Kernel transform. Under the closed world assumption compute the
set of selectors dispatched dynamically, then mark all procedures that don't
match any of those selectors as 'not-dispatched-dynamically'.
Step 2: VM backend. When building IR for a function if this function was
marked as not-dispatched-dynamically then omit type checks for any parameter
that is not marked as generic-covariant-impl, as such arguments are guaranteed
to be checked on the caller side (by front-end).
+------------------------+------------+----------+-----------+--------------+
| benchmark | baseline | current | with opt | improved by |
+------------------------+------------+----------+-----------+--------------+
| stock_layout_iteration | 2366.3786 | 2724.3 | 2562.75 | -5.93% |
| stock_build_iteration | 3824.3 | 4914.8 | 4681 | -4.76% |
+------------------------+------------+----------+-----------+--------------+
* Flutter gallery Instructions size is reduced by 11% (8748720 bytes to 7846368 bytes).
Baseline is at 6196496 bytes.
Alternatively to annotating individual procedures, I considered annotating Program node
with a set of dynamically dispatched selectors. Decoding and passing this information
around proved to be quite cumbersome in the "streaming" world, so I opted for a simpler
approach where all individual procedures are annotated.
Bug: https://github.com/dart-lang/sdk/issues/3179
Change-Id: I2f32a609e3872c74d5ae7bbd97555453aaedf15f
Reviewed-on: https://dart-review.googlesource.com/38125
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Samir Jindel <sjindel@google.com>
This reverts commit 75a9579ea0.
Reason for revert: function_subtype_bound_closure7_test fails in darkp
Original change's description:
> [vm/kernel/aot] Skip unnecessary type checks on parameters of instance methods.
>
> The approach works as follows:
>
> Step 1: Kernel transform. Under the closed world assumption compute the
> set of selectors dispatched dynamically, then mark all procedures that don't
> match any of those selectors as 'not-dispatched-dynamically'.
>
> Step 2: VM backend. When building IR for a function if this function was
> marked as not-dispatched-dynamically then omit type checks for any parameter
> that is not marked as generic-covariant-impl, as such arguments are guaranteed
> to be checked on the caller side (by front-end).
>
> # Performance Impact
>
> +------------------------+------------+----------+-----------+--------------+
> | benchmark | baseline | current | with opt | improved by |
> +------------------------+------------+----------+-----------+--------------+
> | stock_layout_iteration | 2366.3786 | 2724.3 | 2562.75 | -5.93% |
> | stock_build_iteration | 3824.3 | 4914.8 | 4681 | -4.76% |
> +------------------------+------------+----------+-----------+--------------+
>
> * Flutter gallery Instructions size is reduced by 11% (8748720 bytes to 7846368 bytes).
> Baseline is at 6196496 bytes.
>
> # Alternative Implementations
>
> Alternatively to annotating individual procedures, I considered annotating Program node
> with a set of dynamically dispatched selectors. Decoding and passing this information
> around proved to be quite cumbersome in the "streaming" world, so I opted for a simpler
> approach where all individual procedures are annotated.
>
> Change-Id: I363db6d5dd1138fe25917646313c16d0b213c3b4
> Reviewed-on: https://dart-review.googlesource.com/37822
> Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
> Reviewed-by: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Samir Jindel <sjindel@google.com>
TBR=vegorov@google.com,alexmarkov@google.com,sjindel@google.com
Change-Id: I0fd6bf3e6edfc3e605da2b996f9a0da6c409d01c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/37802
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
The approach works as follows:
Step 1: Kernel transform. Under the closed world assumption compute the
set of selectors dispatched dynamically, then mark all procedures that don't
match any of those selectors as 'not-dispatched-dynamically'.
Step 2: VM backend. When building IR for a function if this function was
marked as not-dispatched-dynamically then omit type checks for any parameter
that is not marked as generic-covariant-impl, as such arguments are guaranteed
to be checked on the caller side (by front-end).
# Performance Impact
+------------------------+------------+----------+-----------+--------------+
| benchmark | baseline | current | with opt | improved by |
+------------------------+------------+----------+-----------+--------------+
| stock_layout_iteration | 2366.3786 | 2724.3 | 2562.75 | -5.93% |
| stock_build_iteration | 3824.3 | 4914.8 | 4681 | -4.76% |
+------------------------+------------+----------+-----------+--------------+
* Flutter gallery Instructions size is reduced by 11% (8748720 bytes to 7846368 bytes).
Baseline is at 6196496 bytes.
# Alternative Implementations
Alternatively to annotating individual procedures, I considered annotating Program node
with a set of dynamically dispatched selectors. Decoding and passing this information
around proved to be quite cumbersome in the "streaming" world, so I opted for a simpler
approach where all individual procedures are annotated.
Change-Id: I363db6d5dd1138fe25917646313c16d0b213c3b4
Reviewed-on: https://dart-review.googlesource.com/37822
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Samir Jindel <sjindel@google.com>
Johnni Winther