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8264945: Optimize the code-gen for Math.pow(x, 0.5) #3404

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@@ -1633,6 +1633,65 @@ bool LibraryCallKit::runtime_math(const TypeFunc* call_type, address funcAddr, c
return true;
}

//------------------------------inline_math_pow-----------------------------
bool LibraryCallKit::inline_math_pow() {
Node* exp = round_double_node(argument(2));
const TypeD* d = _gvn.type(exp)->isa_double_constant();
if (d != NULL) {
if (d->getd() == 2.0) {
// Special case: pow(x, 2.0) => x * x
Node* base = round_double_node(argument(0));
set_result(_gvn.transform(new MulDNode(base, base)));
return true;
}
#if defined(X86) && defined(_LP64)
else if (d->getd() == 0.5 && Matcher::match_rule_supported(Op_SqrtD)) {
// Special case: pow(x, 0.5) => sqrt(x)
Node* base = round_double_node(argument(0));
Node* zero = _gvn.zerocon(T_DOUBLE);

RegionNode* region = new RegionNode(3);
Node* phi = new PhiNode(region, Type::DOUBLE);

Node* cmp = _gvn.transform(new CmpDNode(base, zero));
Node* test = _gvn.transform(new BoolNode(cmp, BoolTest::lt));

Node* if_pow = generate_slow_guard(test, NULL);
Node* value_sqrt = _gvn.transform(new SqrtDNode(C, control(), base));
phi->init_req(1, value_sqrt);
region->init_req(1, control());

if (if_pow != NULL) {
set_control(if_pow);
address target = StubRoutines::dpow() != NULL ? StubRoutines::dpow() :
CAST_FROM_FN_PTR(address, SharedRuntime::dpow);
const TypePtr* no_memory_effects = NULL;
Node* trig = make_runtime_call(RC_LEAF, OptoRuntime::Math_DD_D_Type(), target, "POW",
no_memory_effects, base, top(), exp, top());
Node* value_pow = _gvn.transform(new ProjNode(trig, TypeFunc::Parms+0));
#ifdef ASSERT
Node* value_top = _gvn.transform(new ProjNode(trig, TypeFunc::Parms+1));
assert(value_top == top(), "second value must be top");
#endif
phi->init_req(2, value_pow);
region->init_req(2, _gvn.transform(new ProjNode(trig, TypeFunc::Control)));
}

C->set_has_split_ifs(true); // Has chance for split-if optimization
set_control(_gvn.transform(region));
record_for_igvn(region);
set_result(_gvn.transform(phi));

return true;
}
#endif // defined(X86) && defined(_LP64)
}

return StubRoutines::dpow() != NULL ?
runtime_math(OptoRuntime::Math_DD_D_Type(), StubRoutines::dpow(), "dpow") :
runtime_math(OptoRuntime::Math_DD_D_Type(), CAST_FROM_FN_PTR(address, SharedRuntime::dpow), "POW");
}

//------------------------------inline_math_native-----------------------------
bool LibraryCallKit::inline_math_native(vmIntrinsics::ID id) {
#define FN_PTR(f) CAST_FROM_FN_PTR(address, f)
@@ -1673,21 +1732,9 @@ bool LibraryCallKit::inline_math_native(vmIntrinsics::ID id) {
return StubRoutines::dexp() != NULL ?
runtime_math(OptoRuntime::Math_D_D_Type(), StubRoutines::dexp(), "dexp") :
runtime_math(OptoRuntime::Math_D_D_Type(), FN_PTR(SharedRuntime::dexp), "EXP");
case vmIntrinsics::_dpow: {
Node* exp = round_double_node(argument(2));
const TypeD* d = _gvn.type(exp)->isa_double_constant();
if (d != NULL && d->getd() == 2.0) {
// Special case: pow(x, 2.0) => x * x
Node* base = round_double_node(argument(0));
set_result(_gvn.transform(new MulDNode(base, base)));
return true;
}
return StubRoutines::dpow() != NULL ?
runtime_math(OptoRuntime::Math_DD_D_Type(), StubRoutines::dpow(), "dpow") :
runtime_math(OptoRuntime::Math_DD_D_Type(), FN_PTR(SharedRuntime::dpow), "POW");
}
#undef FN_PTR

case vmIntrinsics::_dpow: return inline_math_pow();
case vmIntrinsics::_dcopySign: return inline_double_math(id);
case vmIntrinsics::_fcopySign: return inline_math(id);
case vmIntrinsics::_dsignum: return inline_double_math(id);
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@@ -201,6 +201,7 @@ class LibraryCallKit : public GraphKit {
bool inline_math_native(vmIntrinsics::ID id);
bool inline_math(vmIntrinsics::ID id);
bool inline_double_math(vmIntrinsics::ID id);
bool inline_math_pow();
template <typename OverflowOp>
bool inline_math_overflow(Node* arg1, Node* arg2);
void inline_math_mathExact(Node* math, Node* test);