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// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "include/v8config.h"
#include "src/trap-handler/trap-handler-simulator.h"
#include "src/trap-handler/trap-handler.h"
#if V8_TRAP_HANDLER_SUPPORTED
#if V8_OS_DARWIN
#define SYMBOL(name) "_" #name
#else // !V8_OS_DARWIN
#define SYMBOL(name) #name
#endif // !V8_OS_DARWIN
// Define the ProbeMemory function declared in trap-handler-simulators.h.
asm(
".globl " SYMBOL(ProbeMemory) " \n"
SYMBOL(ProbeMemory) ": \n"
// First parameter (address) passed in %rdi on Linux/Mac, and %rcx on Windows.
// The second parameter (pc) is unused here. It is read by the trap handler
// instead.
#if V8_OS_WIN
" movb (%rcx), %al \n"
#else
" movb (%rdi), %al \n"
#endif // V8_OS_WIN
// Return 0 on success.
" xorl %eax, %eax \n"
// Place an additional "ret" here instead of falling through to the one
// below, because (some) toolchain(s) on Mac set ".subsections_via_symbols",
// which can cause the "ret" below to be placed elsewhere. An alternative
// prevention would be to add ".alt_entry" (see
// https://reviews.llvm.org/D79926), but just adding a "ret" is simpler.
" ret \n"
".globl " SYMBOL(v8_probe_memory_continuation) "\n"
SYMBOL(v8_probe_memory_continuation) ": \n"
// If the trap handler continues here, it wrote the landing pad in %rax.
" ret \n");
#endif
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