AMD64GuardedDevirtualSnippet.cpp

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#include "x/amd64/codegen/AMD64GuardedDevirtualSnippet.hpp"

#include <stddef.h>
#include "codegen/GuardedDevirtualSnippet.hpp"
#include "codegen/CodeGenerator.hpp"
#include "codegen/Linkage.hpp"
#include "codegen/Linkage_inlines.hpp"
#include "il/LabelSymbol.hpp"
#include "il/MethodSymbol.hpp"
#include "il/Symbol.hpp"

uint8_t *TR::AMD64GuardedDevirtualSnippet::loadArgumentsIfNecessary(TR::Node *callNode, uint8_t *cursor, bool calculateSizeOnly, int32_t *sizeOfFlushArea)
   {
   if (!_realMethodSymbolReference)
      return cursor;

   TR::MethodSymbol    *methodSymbol = _realMethodSymbolReference->getSymbol()->castToMethodSymbol();
   if (isLoadArgumentsNecessary(methodSymbol))
      {
      // Devirtualized VMInternalNatives have their args evaluated to the
      // stack, so we must load them into regs before the vft dispatch
      TR::Linkage *linkage = cg()->getLinkage(methodSymbol->getLinkageConvention());
      cursor = linkage->loadArguments(callNode, cursor, calculateSizeOnly, sizeOfFlushArea, false);
      }
   return cursor;
   }

uint8_t *TR::AMD64GuardedDevirtualSnippet::emitSnippetBody()
   {
   uint8_t *buffer = cg()->getBinaryBufferCursor();
   uint8_t *cursor = loadArgumentsIfNecessary(getNode(), buffer, false, NULL);
   cg()->setBinaryBufferCursor(cursor);
   cursor = TR::X86GuardedDevirtualSnippet::emitSnippetBody();
   getSnippetLabel()->setCodeLocation(buffer);
   cg()->setBinaryBufferCursor(buffer);
   return cursor;
   }

uint32_t TR::AMD64GuardedDevirtualSnippet::getLength(int32_t estimatedSnippetStart)
   {
   int32_t sizeOfFlushArea = 0;
   loadArgumentsIfNecessary(getNode(), (uint8_t*)0 + estimatedSnippetStart, true, &sizeOfFlushArea);
   return sizeOfFlushArea + TR::X86GuardedDevirtualSnippet::getLength(estimatedSnippetStart + sizeOfFlushArea);
   }

bool TR::AMD64GuardedDevirtualSnippet::isLoadArgumentsNecessary(TR::MethodSymbol *methodSymbol)
   {
   return (methodSymbol && methodSymbol->isVMInternalNative());
   }