ForceRecompilationSnippet.cpp

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 * Copyright (c) 2000, 2020 IBM Corp. and others
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution and
 * is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following
 * Secondary Licenses when the conditions for such availability set
 * forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
 * General Public License, version 2 with the GNU Classpath
 * Exception [1] and GNU General Public License, version 2 with the
 * OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
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 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception
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#include "x/codegen/ForceRecompilationSnippet.hpp"

#include "codegen/Relocation.hpp"
#include "env/CompilerEnv.hpp"
#include "env/IO.hpp"
#include "env/OMRMemory.hpp"
#include "env/jittypes.h"
#include "env/VMJ9.h"
#include "il/LabelSymbol.hpp"
#include "il/MethodSymbol.hpp"
#include "il/Node.hpp"
#include "il/Node_inlines.hpp"
#include "il/RegisterMappedSymbol.hpp"
#include "il/ResolvedMethodSymbol.hpp"
#include "il/StaticSymbol.hpp"
#include "il/Symbol.hpp"
#include "runtime/CodeCacheManager.hpp"
#include "x/codegen/X86Recompilation.hpp"

// TODO: Combine this with TR::X86RecompilationSnippet
// TODO: This class should be named TR::X86InduceRecompilationSnippet

uint8_t *TR::X86ForceRecompilationSnippet::emitSnippetBody()
   {
   TR_J9VMBase *fej9 = (TR_J9VMBase *)(cg()->fe());
   uint8_t *buffer = cg()->getBinaryBufferCursor();
   getSnippetLabel()->setCodeLocation(buffer);

   TR::SymbolReference *helper = cg()->symRefTab()->findOrCreateRuntimeHelper(cg()->comp()->target().is64Bit()? TR_AMD64induceRecompilation : TR_IA32induceRecompilation);
   intptr_t helperAddress = (intptr_t)helper->getMethodAddress();
   *buffer++ = 0xe8; // CallImm4
   if (NEEDS_TRAMPOLINE(helperAddress, buffer+4, cg()))
      {
      helperAddress = TR::CodeCacheManager::instance()->findHelperTrampoline(helper->getReferenceNumber(), (void *)buffer);
      TR_ASSERT(IS_32BIT_RIP(helperAddress, buffer+4), "Local helper trampoline should be reachable directly.\n");
      }
   *(int32_t *)buffer = ((uint8_t*)helperAddress - buffer) - 4;

   cg()->addExternalRelocation(new (cg()->trHeapMemory())
      TR::ExternalRelocation(
         buffer,
         (uint8_t *)helper,
         TR_HelperAddress, cg()),
         __FILE__, __LINE__, getNode());

   buffer += 4;

   uint8_t *bufferBase = buffer;

   buffer = genRestartJump(buffer);

   // Offset to the startPC.  We don't store the startPC itself, because on
   // AMD64 that would require 4 more bytes.
   //
   *(uint32_t *)buffer = (uint32_t)(cg()->getCodeStart() - bufferBase);
   buffer += 4;

   return buffer;
   }


void
TR_Debug::print(TR::FILE *pOutFile, TR::X86ForceRecompilationSnippet  * snippet)
   {
   if (pOutFile == NULL)
      return;

   uint8_t *bufferPos = snippet->getSnippetLabel()->getCodeLocation();
   printSnippetLabel(pOutFile, snippet->getSnippetLabel(), bufferPos, getName(snippet));

   TR::SymbolReference *helper        = _cg->getSymRef(_comp->target().is64Bit()? TR_AMD64induceRecompilation : TR_IA32induceRecompilation);
   intptr_t           helperAddress = (intptr_t)helper->getMethodAddress();
   printPrefix(pOutFile, NULL, bufferPos, 5);
   trfprintf(pOutFile, "call\t%s \t%s Helper Address = " POINTER_PRINTF_FORMAT,
                 getName(helper),
                 commentString(),
                 helperAddress);
   bufferPos += 5;

   uint8_t *offsetBase = bufferPos;

   printPrefix(pOutFile, NULL, bufferPos, 5);
   printLabelInstruction(pOutFile, "jmp", snippet->getRestartLabel());
   bufferPos += 5;

   printPrefix(pOutFile, NULL, bufferPos, 4);
   trfprintf(pOutFile, "%s  \t%s%08x%s\t\t%s Offset to startPC",
                 ddString(),
                 hexPrefixString(),
                 _cg->getCodeStart() - offsetBase,
                 hexSuffixString(),
                 commentString());
   bufferPos += 4;
   }


uint32_t TR::X86ForceRecompilationSnippet::getLength(int32_t estimatedSnippetStart)
   {
   return 14;
   }