Changeset 281718 in webkit for trunk/Source/JavaScriptCore/assembler/MacroAssemblerMIPS.cpp

Timestamp:

Aug 27, 2021, 1:49:34 PM (4 years ago)

Author:

[email protected]

Message:

Make ARM64 and X86_64 probe code a little bit more efficient.
​https://bugs.webkit.org/show_bug.cgi?id=229618
rdar://82445743

Reviewed by Yusuke Suzuki.

We were using an unnecessary indirect call to call Probe::executeProbe() when we
can be using a direct call, which emits less JIT code. This patch changes the
ARM64 and X86_64 ports to use a direct call now.

Also rename executeProbe to executeJSCJITProbe to make it more unique since we're
switching to extern "C" linkage for this function now.

For MacroAssemblerX86Common.cpp, we left the X86 and MSVC implementations unchanged.
For X86, I don't know the stack alignment requirements (if any) plus we might want
to delete this code eventually since we're not supporting the X86 JIT anymore.
For MSVC, I don't know the way to express a direct call in MSVC assembly, and have
no way to test it. Will leave that as an exercise for folks working on the Windows
ports if they are interested.

Also remove JITProbeExecutorPtrTag since it's no longer needed.

• assembler/MacroAssemblerARM64.cpp:

(JSC::MacroAssembler::probe):

• assembler/MacroAssemblerARMv7.cpp:

(JSC::MacroAssembler::probe):

• assembler/MacroAssemblerMIPS.cpp:

(JSC::MacroAssembler::probe):

• assembler/MacroAssemblerX86Common.cpp:

(JSC::ctiMasmProbeTrampoline):
(JSC::MacroAssembler::probe):

• assembler/ProbeContext.cpp:

(JSC::Probe::executeJSCJITProbe):
(JSC::Probe::executeProbe): Deleted.

• assembler/ProbeContext.h:
• runtime/JSCPtrTag.h:

File:

• trunk/Source/JavaScriptCore/assembler/MacroAssemblerMIPS.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/assembler/MacroAssemblerMIPS.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2021 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -305 +305 @@
     //     a0: probe function
     //     a1: probe arg
-    //     a2: Probe::executeProbe
+    //     a2: Probe::executeJSCJITProbe
     //     s0: scratch, was ctiMasmProbeTrampoline
     //     s1: scratch
@@ -395 +395 @@
     "move      $a0, $sp" "\n" // Set the Probe::State* arg.
     "addiu     $sp, $sp, -16" "\n" // Allocate stack space for (unused) 16 bytes (8-byte aligned) for 4 arguments.
-    "move      $t9, $a2" "\n" // Probe::executeProbe()
+    "move      $t9, $a2" "\n" // Probe::executeJSCJITProbe()
     "jalr      $t9" "\n" // Call the probe handler.
     "nop" "\n"
@@ -509 +509 @@
     // either modify ra or pc, but not both in the same probe invocation. The probe
     // mechanism ensures that we never try to modify both ra and pc with a RELEASE_ASSERT
-    // in Probe::executeProbe().
+    // in Probe::executeJSCJITProbe().
 
     // Determine if the probe handler changed the pc.
@@ -564 +564 @@
     move(TrustedImmPtr(reinterpret_cast<void*>(function)), a0);
     move(TrustedImmPtr(arg), a1);
-    move(TrustedImmPtr(reinterpret_cast<void*>(Probe::executeProbe)), a2);
+    move(TrustedImmPtr(reinterpret_cast<void*>(Probe::executeJSCJITProbe)), a2);
     move(TrustedImmPtr(reinterpret_cast<void*>(ctiMasmProbeTrampoline)), s0);
     m_assembler.jalr(s0);