This CL introduces new IL instruction, CheckNullInstr, for testing
if an object is null. This instruction will be used to ensure
correctness when AOT relies on strong mode types, which are nullable
by default (unless proven otherwise).
Code generation of CheckNullInstr is implemented without major code
duplication between different CPUs using common macro-assembler
pseudo-instructions implemented by all platforms.
Also, code generation of GenericCheckBoundInstr is refactored in
the similar way.
Issue: https://github.com/dart-lang/sdk/issues/30480
Change-Id: I35e9b556302fe7db98ce5167b3601f08ddbee642
Reviewed-on: https://dart-review.googlesource.com/4540
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
Previously these functions would only contain a single CheckStackOverflowInstr
in a backtracking block and that CheckStackOverflowInstr would have a zero
loop_depth - which means it would not be considered eligable for OSR.
This change:
* adds CheckStackOverflowInstr with non-zero loop_depth in two other places
(Boyer-Moore lookahead skip loop and greedy loop) where loops arise in the
generated IL;
* sets non-zero loop depth on the CheckStackOverflowInstr in the backtracking
block;
* adds a flag on CheckStackOverflowInstr that allows optimizing compiler to
optimize away those checks that were inserted solely to serve as OSR entries.
* ensures that IR generated by IRRegExpMacroAssembler is OSR compatible:
* GraphEntryInstr has correct osr_id;
* GraphEntry and normal entry have different block ids (B0 and B1 - instead of B0 and B0);
* unreachable blocks are pruned and GraphEntry is rewired to point to OSR entry;
* IRRegExpMacroAssembler::GrowStack should not assume that stack_array_cell and :stack
are always in sync, because :stack can come from OSR or deoptimization why stack_array_cell
is a constant associated with a particular Code object.
* refactors the way the RegExp stack was growing: instead of having a special instruction
just emit a call to a Dart function;
* refactors the way block pruning for OSR is done by consolidating duplicated code
in a single function.
We allow the optimizing compiler to remove preemption checks from
non-backtracking loops in the regexp code because those loops
unlike backtracking have guaranteed O(input_length) time
complexity.
Performance Implications
------------------------
This change improves performance of regexps in cases where regexp spends a lot
of time in the first invocation (either due to backtracking or due to long non
matching prefix) by allowing VM to optimize the :matcher while :matcher is
running.
For example on regex-redux[1] benchmark it improves Dart performance by 3x
(from ~18s to ~6s on my Mac Book Pro).
CL history
----------
This relands commit d87cc52c3e.
Original code review: https://codereview.chromium.org/2950783003/
[1] https://benchmarksgame.alioth.debian.org/u64q/program.php?test=regexredux&lang=dart&id=2R=erikcorry@google.com
Review-Url: https://codereview.chromium.org/2951053003 .
i.e. #ifndef VM_WHATEVER -> #ifndef RUNTIME_VM_WHATEVER
This lets us remove a hack from the PRESUBMIT.py script that existed
for reasons that are no longer valid, and sets us up to add some
presubmit checks for the GN build.
R=asiva@google.com, rmacnak@google.com
Review URL: https://codereview.chromium.org/2450713004 .
Expand the range on a miss if all classes in the range have the same lookup result, otherwise transition to the stub that does a linear scan of ICData.
Because we do a depth-first sort of classes during AOT, if a call site sees only objects all inheriting the same function as the call target, the call site will be handled by this new stub.
Adjust LoadClassIdMayBeSmi on x64 to preserve the object.
R=fschneider@google.com
Review URL: https://codereview.chromium.org/2279563002 .
The call sequence is very similar to a classic IC call, except the guarded class and the target are loaded indirectly from the constant pool instead of as immediates. In the monomorphic case, we call directly to the expected target with a class check in the callee. In the unlinked, polymorphic and megamorphic cases, we call a stub; these case are now call-through instead of call-and-return.
Every code, except stubs involved in switchable calls, includes the class check sequence at the beginning. So we now distinguish between a checked and an unchecked entry point. Generated code except the switchable call continues to use the unchecked entry point.
PC offsets are calculated relative to the beginning of the instruction stream, rather than either entry point.
BUG=
R=fschneider@google.com
Review URL: https://codereview.chromium.org/2226893002 .
1. Make CheckArrayBoundInstr also check the index for smi. This allows easy replacement
of the deoptimizing checks with the slow-path checks in the precompiler.
2. Add GenericCheckBoundInstr which has a slow-path attached for
handling check failures.
BUG=
R=rmacnak@google.com, vegorov@google.com
Review URL: https://codereview.chromium.org/2149023002 .
Committed: 4a5f651c4b
1. Make CheckArrayBoundInstr also check the index for smi. This allows easy replacement
of the deoptimizing checks with the slow-path checks in the precompiler.
2. Add GenericCheckBoundInstr which has a slow-path attached for
handling check failures.
BUG=
R=vegorov@google.com
Review URL: https://codereview.chromium.org/2149023002 .
Instead of calling code object directly, call indirectly and
pass the code object in a register. The object pool is then loaded from
the code object. This is another preparation step for making generated code
relocatable.
All non-ia32 platforms:
No entry patching.
ARM:
PC marker (now code object) moves to the same place as on x64 (below saved PP, above saved FP).
R9 is now used as PP, R10 as CODE_REG.
BUG=
R=koda@google.com, rmacnak@google.com
Committed: 1d343e5a7b
Review URL: https://codereview.chromium.org//1192103004 .
Instead of calling code object directly, call indirectly and
pass the code object in a register. The object pool is then loaded from
the code object. This is another preparation step for making generated code
relocatable.
All non-ia32 platforms:
No entry patching.
ARM:
PC marker (now code object) moves to the same place as on x64 (below saved PP, above saved FP).
R9 is now used as PP, R10 as CODE_REG.
BUG=
R=rmacnak@google.com
Review URL: https://codereview.chromium.org//1192103004 .
