int32_t
OMR::X86::I386::CodeGenerator::getMaximumNumberOfGPRsAllowedAcrossEdge(TR::Node *node)
{
// TODO: Currently, lookupEvaluator doesn't deal properly with different
// glRegDeps on different cases of a lookupswitch.
//
static const char *enableLookupswitch = feGetEnv("TR_enableGRAAcrossLookupSwitch");
if (!enableLookupswitch && node->getOpCode().getOpCodeValue()==TR::lookup)
return 1;
if (node->getOpCode().getOpCodeValue()==TR::table)
{
// 1 for jump table base reg, which is not apparent in the trees
// 1 for ebp when it is needed for the VMThread
//
return self()->getNumberOfGlobalGPRs() - 2;
}
if (node->getOpCode().isIf())
{
// we run out of all but one/two registers in these cases
//
if (node->getFirstChild()->getType().isInt64())
{
if (node->getOpCode().isBranch())
{
TR::Node *firstChild = node->getFirstChild();
TR::Node *secondChild = node->getSecondChild();
int extraRegsAvailable = 0;
if(firstChild->getOpCodeValue() == TR::d2l ||
secondChild->getOpCodeValue() == TR::d2l)
{
return 1;
}
if ((firstChild->getReferenceCount() == 1 &&
firstChild->getOpCode().isLoadVarDirect()) ||
(secondChild->getReferenceCount() == 1 &&
firstChild->getOpCode().isLoadVarDirect()))
extraRegsAvailable += 0; // TODO: put it back to 2 when looking at GRA, GRA pushes allocation of 8 registers
return 2 + extraRegsAvailable;
}
else
{
// TR_lcmpXX opcodes take up 5 regs
//
return 1;
}
}
// we run out of all but one register in these cases....last time I tried....
//
if (node->getFirstChild()->getOpCodeValue() == TR::instanceof)
{
if (!TR::TreeEvaluator::instanceOfOrCheckCastNeedSuperTest(node->getFirstChild(), self()) &&
TR::TreeEvaluator::instanceOfOrCheckCastNeedEqualityTest(node->getFirstChild(), self()))
return self()->getNumberOfGlobalGPRs() - 4; // ebp plus three other regs if vft masking is enabled
else
return 0;
}
// All other conditional branches, we usually need one reg for the compare and possibly one for the vmthread
//return getNumberOfGlobalGPRs() - 1 - (node->isVMThreadRequired()? 1 : 0);
// vmThread required might be set on a node after GRA has ran
return self()->getNumberOfGlobalGPRs() - 2;
}
return INT_MAX;
}
