tree 348dd8d894201d2474403fe51269f85996e35562
parent c78ef90124dfb84215805a19eb91783b0f7ef7e9
author Clement Skau <cskau@google.com> 1648637846 +0000
committer Commit Bot <commit-bot@chromium.org> 1648637846 +0000

[vm] Avoid spills for most FFI leaf calls.

Adds an additional `contains_call` mode specifying that the
register allocator should block all non-callee-save ABI registers.
As opposed to `kCall`, this frees the use of callee-save registers
across FfiCallInstr, meaning that live values do not always have
to be spilled.
For architectures with sufficient free callee-save registers
this should result in less overhead for each FfiCall.

This change also removes RequiresStackSlot as it was only being
used for FfiCall's TypedData, and wasn't implemented in the
Register Allocator.
Since FfiCall no longer blocks all registers TypedData can now
live in a register, so the previous assumptions about it always
being on stack have to be relaxed.

This change also works around an issue where the register allocator
might allocate an FPU register that does not have an associated S
register. This causes problems when FFI tries to pass 32 bit floats
in said register.
As a work around we block all FPU regs. above the 8 that have S regs.
for FFI calls in VFPv3-D32 mode.

This change also adds an additional temp registers which was previous
used but not being reserved in FfiCall IL on Arm64.

Some additional prereq. fixes were branched out into:
https://dart-review.googlesource.com/c/sdk/+/237690

TEST=Adds IRTest_FfiCallInstrLeafDoesntSpill.

Bug: https://github.com/dart-lang/sdk/issues/45468
Change-Id: Icdeccb0de77e46f5bc34dd5bd4e308d27bc1ef99
Cq-Do-Not-Cancel-Tryjobs: true
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-win-release-x64-try, vm-precomp-ffi-qemu-linux-release-arm-try, vm-kernel-mac-release-arm64-try, vm-kernel-nnbd-mac-debug-arm64-try, vm-kernel-nnbd-mac-release-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/221624
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Clement Skau <cskau@google.com>