SSATmp* TraceBuilder::optimizeWork(IRInstruction* inst,
const folly::Optional<IdomVector>& idoms) {
// Since some of these optimizations inspect tracked state, we don't
// perform any of them on non-main traces.
if (m_savedTraces.size() > 0) return nullptr;
static DEBUG_ONLY __thread int instNest = 0;
if (debug) ++instNest;
SCOPE_EXIT { if (debug) --instNest; };
DEBUG_ONLY auto indent = [&] { return std::string(instNest * 2, ' '); };
FTRACE(1, "{}{}\n", indent(), inst->toString());
// First pass of tracebuilder optimizations try to replace an
// instruction based on tracked state before we do anything else.
// May mutate the IRInstruction in place (and return nullptr) or
// return an SSATmp*.
if (SSATmp* preOpt = preOptimize(inst)) {
FTRACE(1, " {}preOptimize returned: {}\n",
indent(), preOpt->inst()->toString());
return preOpt;
}
if (inst->op() == Nop) return nullptr;
// copy propagation on inst source operands
copyProp(inst);
SSATmp* result = nullptr;
if (m_enableCse && inst->canCSE()) {
result = cseLookup(inst, idoms);
if (result) {
// Found a dominating instruction that can be used instead of inst
FTRACE(1, " {}cse found: {}\n",
indent(), result->inst()->toString());
assert(!inst->consumesReferences());
if (inst->producesReference()) {
// Replace with an IncRef
FTRACE(1, " {}cse of refcount-producing instruction\n", indent());
return gen(IncRef, result);
} else {
return result;
}
}
}
if (m_enableSimplification) {
result = m_simplifier.simplify(inst);
if (result) {
// Found a simpler instruction that can be used instead of inst
FTRACE(1, " {}simplification returned: {}\n",
indent(), result->inst()->toString());
assert(inst->hasDst());
return result;
}
}
return nullptr;
}
SSATmp* TraceBuilder::optimizeWork(IRInstruction* inst) {
static DEBUG_ONLY __thread int instNest = 0;
if (debug) ++instNest;
SCOPE_EXIT { if (debug) --instNest; };
DEBUG_ONLY auto indent = [&] { return std::string(instNest * 2, ' '); };
FTRACE(1, "{}{}\n", indent(), inst->toString());
// First pass of tracebuilder optimizations try to replace an
// instruction based on tracked state before we do anything else.
// May mutate the IRInstruction in place (and return nullptr) or
// return an SSATmp*.
if (SSATmp* preOpt = preOptimize(inst)) {
FTRACE(1, " {}preOptimize returned: {}\n",
indent(), preOpt->inst()->toString());
return preOpt;
}
if (inst->op() == Nop) return nullptr;
// copy propagation on inst source operands
copyProp(inst);
SSATmp* result = nullptr;
if (m_enableCse && inst->canCSE()) {
result = cseLookup(inst);
if (result) {
// Found a dominating instruction that can be used instead of inst
FTRACE(1, " {}cse found: {}\n",
indent(), result->inst()->toString());
return result;
}
}
if (m_enableSimplification) {
result = m_simplifier.simplify(inst);
if (result) {
// Found a simpler instruction that can be used instead of inst
FTRACE(1, " {}simplification returned: {}\n",
indent(), result->inst()->toString());
assert(inst->hasDst());
return result;
}
}
return nullptr;
}