Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 0b7790f1f183a9df21c5c67840bc2400d1c85f35
https://github.com/WebKit/WebKit/commit/0b7790f1f183a9df21c5c67840bc2400d1c85f35
Author: David Degazio <[email protected]>
Date: 2023-05-03 (Wed, 03 May 2023)
Changed paths:
M Source/JavaScriptCore/wasm/WasmBBQJIT.cpp
Log Message:
-----------
Eliminate redundant reloading of registers when calling functions in BBQ JIT
https://bugs.webkit.org/show_bug.cgi?id=256235
rdar://108812140
Reviewed by Justin Michaud.
Unifies BBQJIT::saveValuesAcrossCall and BBQJIT::passParametersToCall, and
applies the following changes:
- Tracks the original location of each argument before saving/flushing them,
and use these when passing parameters. We can only do this because we don't
assign any new registers or clobber any values between saving caller-saves
and calling the function.
- Consumes each argument before saving caller-saves instead of after. This
means
we don't redundantly save values whose lifetimes have obviously ended (WASM
temps).
- Emits a shuffle instead of naive moves when passing values via the calling
convention. Because we now use the original argument locations, which may be
registers, we need this in case of overlap with the calling convention
registers.
Altogether, this means we save a bunch of redundant instructions in BBQ JIT
calls
(in my experience, one load/store pair per argument for most arguments in most
calls),
due to avoiding storing then reloading values unnecessarily. This should benefit
overall runtime performance for BBQ-compiled functions, as well as generated
code
size.
* Source/JavaScriptCore/wasm/WasmBBQJIT.cpp:
(JSC::Wasm::BBQJIT::saveValuesAcrossCallAndPassArguments):
(JSC::Wasm::BBQJIT::emitCCall):
(JSC::Wasm::BBQJIT::addCall):
(JSC::Wasm::BBQJIT::emitIndirectCall):
(JSC::Wasm::BBQJIT::emitShuffle):
(JSC::Wasm::BBQJIT::saveValuesAcrossCall): Deleted.
(JSC::Wasm::BBQJIT::passParametersToCall): Deleted.
Canonical link: https://commits.webkit.org/263638@main
_______________________________________________
webkit-changes mailing list
[email protected]
https://lists.webkit.org/mailman/listinfo/webkit-changes
