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/*
* Copyright (C) 2015-2017 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#if ENABLE(B3_JIT)
#include "B3Type.h"
#include "B3Width.h"
#include <wtf/Optional.h>
#include <wtf/StdLibExtras.h>
namespace JSC { namespace B3 {
// Warning: In B3, an Opcode is just one part of a Kind. Kind is used the way that an opcode
// would be used in simple IRs. See B3Kind.h.
enum Opcode : int16_t {
// A no-op that returns Void, useful for when you want to remove a value.
Nop,
// Polymorphic identity, usable with any value type.
Identity,
// This is an identity, but we prohibit the compiler from realizing this until the bitter end. This can
// be used to block reassociation and other compiler reasoning, if we find that it's wrong or
// unprofitable and we need an escape hatch.
Opaque,
// Constants. Use the ConstValue* classes. Constants exist in the control flow, so that we can
// reason about where we would construct them. Large constants are expensive to create.
Const32,
Const64,
ConstDouble,
ConstFloat,
// B3 supports non-SSA variables. These are accessed using Get and Set opcodes. Use the
// VariableValue class. It's a good idea to run fixSSA() to turn these into SSA. The
// optimizer will do that eventually, but if your input tends to use these opcodes, you
// should run fixSSA() directly before launching the optimizer.
Set,
Get,
// Gets the base address of a StackSlot.
SlotBase,
// The magical argument register. This is viewed as executing at the top of the program
// regardless of where in control flow you put it, and the compiler takes care to ensure that we
// don't clobber the value by register allocation or calls (either by saving the argument to the
// stack or preserving it in a callee-save register). Use the ArgumentRegValue class. The return
// type is either pointer() (for GPRs) or Double (for FPRs).
ArgumentReg,
// The frame pointer. You can put this anywhere in control flow but it will always yield the
// frame pointer, with a caveat: if our compiler changes the frame pointer temporarily for some
// silly reason, the FramePointer intrinsic will return where the frame pointer *should* be not
// where it happens to be right now.
FramePointer,
// Polymorphic math, usable with any value type.
Add,
Sub,
Mul,
Div, // All bets are off as to what will happen when you execute this for -2^31/-1 and x/0.
UDiv,
Mod, // All bets are off as to what will happen when you execute this for -2^31%-1 and x%0.
UMod,
// Polymorphic negation. Note that we only need this for floating point, since integer negation
// is exactly like Sub(0, x). But that's not true for floating point. Sub(0, 0) is 0, while
// Neg(0) is -0. Also, we canonicalize Sub(0, x) into Neg(x) in case of integers.
Neg,
// Integer math.
BitAnd,
BitOr,
BitXor,
Shl,
SShr, // Arithmetic Shift.
ZShr, // Logical Shift.
RotR, // Rotate Right.
RotL, // Rotate Left.
Clz, // Count leading zeros.
// Floating point math.
Abs,
Ceil,
Floor,
Sqrt,
// Casts and such.
// Bitwise Cast of Double->Int64 or Int64->Double
BitwiseCast,
// Takes and returns Int32:
SExt8,
SExt16,
// Takes Int32 and returns Int64:
SExt32,
ZExt32,
// Does a bitwise truncation of Int64->Int32 and Double->Float:
Trunc,
// Takes ints and returns floating point value. Note that we don't currently provide the opposite operation,
// because double-to-int conversions have weirdly different semantics on different platforms. Use
// a patchpoint if you need to do that.
IToD,
IToF,
// Convert between double and float.
FloatToDouble,
DoubleToFloat,
// Polymorphic comparisons, usable with any value type. Returns int32 0 or 1. Note that "Not"
// is just Equal(x, 0), and "ToBoolean" is just NotEqual(x, 0).
Equal,
NotEqual,
LessThan,
GreaterThan,
LessEqual,
GreaterEqual,
// Integer comparisons. Returns int32 0 or 1.
Above,
Below,
AboveEqual,
BelowEqual,
// Unordered floating point compare: values are equal or either one is NaN.
EqualOrUnordered,
// SSA form of conditional move. The first child is evaluated for truthiness. If true, the second child
// is returned. Otherwise, the third child is returned.
Select,
// Memory loads. Opcode indicates how we load and the loaded type. These use MemoryValue.
// These return Int32:
Load8Z,
Load8S,
Load16Z,
Load16S,
// This returns whatever the return type is:
Load,
// Memory stores. Opcode indicates how the value is stored. These use MemoryValue.
// These take an Int32 value:
Store8,
Store16,
// This is a polymorphic store for Int32, Int64, Float, and Double.
Store,
// Atomic compare and swap that returns a boolean. May choose to do nothing and return false. You can
// usually assume that this is faster and results in less code than AtomicStrongCAS, though that's
// not necessarily true on Intel, if instruction selection does its job. Imagine that this opcode is
// as if you did this atomically:
//
// template<typename T>
// bool AtomicWeakCAS(T expectedValue, T newValue, T* ptr)
// {
// if (!rand())
// return false; // Real world example of this: context switch on ARM while doing CAS.
// if (*ptr != expectedValue)
// return false;
// *ptr = newValue;
// return true;
// }
//
// Note that all atomics put the pointer last to be consistent with how loads and stores work. This
// is a goofy tradition, but it's harmless, and better than being inconsistent.
//
// Note that weak CAS has no fencing guarantees when it fails. This means that the following
// transformation is always valid:
//
// Before:
//
// Branch(AtomicWeakCAS(expected, new, ptr))
// Successors: Then:#success, Else:#fail
//
// After:
//
// Branch(Equal(Load(ptr), expected))
// Successors: Then:#attempt, Else:#fail
// BB#attempt:
// Branch(AtomicWeakCAS(expected, new, ptr))
// Successors: Then:#success, Else:#fail
//
// Both kinds of CAS for non-canonical widths (Width8 and Width16) ignore the irrelevant bits of the
// input.
AtomicWeakCAS,
// Atomic compare and swap that returns the old value. Does not have the nondeterminism of WeakCAS.
// This is a bit more code and a bit slower in some cases, though not by a lot. Imagine that this
// opcode is as if you did this atomically:
//
// template<typename T>
// T AtomicStrongCAS(T expectedValue, T newValue, T* ptr)
// {
// T oldValue = *ptr;
// if (oldValue == expectedValue)
// *ptr = newValue;
// return oldValue
// }
//
// AtomicStrongCAS sign-extends its result for subwidth operations.
//
// Note that AtomicWeakCAS and AtomicStrongCAS sort of have this kind of equivalence:
//
// AtomicWeakCAS(@exp, @new, @ptr) == Equal(AtomicStrongCAS(@exp, @new, @ptr), @exp)
//
// Assuming that the WeakCAS does not spuriously fail, of course.
AtomicStrongCAS,
// Atomically ___ a memory location and return the old value. Syntax:
//
// @oldValue = AtomicXchg___(@operand, @ptr)
//
// For non-canonical widths (Width8 and Width16), these return sign-extended results and ignore the
// irrelevant bits of their inputs.
AtomicXchgAdd,
AtomicXchgAnd,
AtomicXchgOr,
AtomicXchgSub,
AtomicXchgXor,
// FIXME: Maybe we should have AtomicXchgNeg.
// https://bugs.webkit.org/show_bug.cgi?id=169252
// Atomically exchange a value with a memory location. Syntax:
//
// @oldValue = AtomicXchg(@newValue, @ptr)
AtomicXchg,
// Introduce an invisible dependency for blocking motion of loads with respect to each other. Syntax:
//
// @result = Depend(@phantom)
//
// This is eventually codegenerated to have local semantics as if we did:
//
// @result = $0
//
// But it ensures that the users of @result cannot execute until @phantom is computed.
//
// The compiler is not allowed to reason about the fact that Depend codegenerates this way. Any kind
// of transformation or analysis that relies on the insight that Depend is really zero is unsound,
// because it unlocks reordering of users of @result and @phantom.
//
// On X86, this is lowered to a load-load fence and @result folds to zero.
//
// On ARM, this is lowered as if like:
//
// @result = BitXor(@phantom, @phantom)
//
// Except that the compiler never gets an opportunity to simplify out the BitXor.
Depend,
// This is used to compute the actual address of a Wasm memory operation. It takes an IntPtr
// and a pinned register then computes the appropriate IntPtr address. For the use-case of
// Wasm it is important that the first child initially be a ZExt32 so the top bits are cleared.
// We do WasmAddress(ZExt32(ptr), ...) so that we can avoid generating extraneous moves in Air.
WasmAddress,
// This is used to represent standalone fences - i.e. fences that are not part of other
// instructions. It's expressive enough to expose mfence on x86 and dmb ish/ishst on ARM. On
// x86, it also acts as a compiler store-store fence in those cases where it would have been a
// dmb ishst on ARM.
Fence,
// This is a regular ordinary C function call, using the system C calling convention. Make sure
// that the arguments are passed using the right types. The first argument is the callee.
CCall,
// This is a patchpoint. Use the PatchpointValue class. This is viewed as behaving like a call,
// but only emits code via a code generation callback. That callback gets to emit code inline.
// You can pass a stackmap along with constraints on how each stackmap argument must be passed.
// It's legal to request that a stackmap argument is in some register and it's legal to request
// that a stackmap argument is at some offset from the top of the argument passing area on the
// stack.
Patchpoint,
// Checked math. Use the CheckValue class. Like a Patchpoint, this takes a code generation
// callback. That callback gets to emit some code after the epilogue, and gets to link the jump
// from the check, and the choice of registers. You also get to supply a stackmap. Note that you
// are not allowed to jump back into the mainline code from your slow path, since the compiler
// will assume that the execution of these instructions proves that overflow didn't happen. For
// example, if you have two CheckAdd's:
//
// a = CheckAdd(x, y)
// b = CheckAdd(x, y)
//
// Then it's valid to change this to:
//
// a = CheckAdd(x, y)
// b = Identity(a)
//
// This is valid regardless of the callbacks used by the two CheckAdds. They may have different
// callbacks. Yet, this transformation is valid even if they are different because we know that
// after the first CheckAdd executes, the second CheckAdd could not have possibly taken slow
// path. Therefore, the second CheckAdd's callback is irrelevant.
//
// Note that the first two children of these operations have ValueRep's as input constraints but do
// not have output constraints.
CheckAdd,
CheckSub,
CheckMul,
// Check that side-exits. Use the CheckValue class. Like CheckAdd and friends, this has a
// stackmap with a generation callback. This takes an int argument that this branches on, with
// full branch fusion in the instruction selector. A true value jumps to the generator's slow
// path. Note that the predicate child is has both an input ValueRep. The input constraint must be
// WarmAny. It will not have an output constraint.
Check,
// Special Wasm opcode that takes a Int32, a special pinned gpr and an offset. This node exists
// to allow us to CSE WasmBoundsChecks if both use the same pointer and one dominates the other.
// Without some such node B3 would not have enough information about the inner workings of wasm
// to be able to perform such optimizations.
WasmBoundsCheck,
// SSA support, in the style of DFG SSA.
Upsilon, // This uses the UpsilonValue class.
Phi,
// Jump.
Jump,
// Polymorphic branch, usable with any integer type. Branches if not equal to zero. The 0-index
// successor is the true successor.
Branch,
// Switch. Switches over either Int32 or Int64. Uses the SwitchValue class.
Switch,
// Multiple entrypoints are supported via the EntrySwitch operation. Place this in the root
// block and list the entrypoints as the successors. All blocks backwards-reachable from
// EntrySwitch are duplicated for each entrypoint.
EntrySwitch,
// Return. Note that B3 procedures don't know their return type, so this can just return any
// type.
Return,
// This is a terminal that indicates that we will never get here.
Oops
};
inline bool isCheckMath(Opcode opcode)
{
switch (opcode) {
case CheckAdd:
case CheckSub:
case CheckMul:
return true;
default:
return false;
}
}
std::optional<Opcode> invertedCompare(Opcode, Type);
inline Opcode constPtrOpcode()
{
if (is64Bit())
return Const64;
return Const32;
}
inline bool isConstant(Opcode opcode)
{
switch (opcode) {
case Const32:
case Const64:
case ConstDouble:
case ConstFloat:
return true;
default:
return false;
}
}
inline Opcode opcodeForConstant(Type type)
{
switch (type) {
case Int32: return Const32;
case Int64: return Const64;
case Float: return ConstFloat;
case Double: return ConstDouble;
default:
RELEASE_ASSERT_NOT_REACHED();
}
}
inline bool isDefinitelyTerminal(Opcode opcode)
{
switch (opcode) {
case Jump:
case Branch:
case Switch:
case Oops:
case Return:
return true;
default:
return false;
}
}
inline bool isLoad(Opcode opcode)
{
switch (opcode) {
case Load8Z:
case Load8S:
case Load16Z:
case Load16S:
case Load:
return true;
default:
return false;
}
}
inline bool isStore(Opcode opcode)
{
switch (opcode) {
case Store8:
case Store16:
case Store:
return true;
default:
return false;
}
}
inline bool isLoadStore(Opcode opcode)
{
switch (opcode) {
case Load8Z:
case Load8S:
case Load16Z:
case Load16S:
case Load:
case Store8:
case Store16:
case Store:
return true;
default:
return false;
}
}
inline bool isAtomic(Opcode opcode)
{
switch (opcode) {
case AtomicWeakCAS:
case AtomicStrongCAS:
case AtomicXchgAdd:
case AtomicXchgAnd:
case AtomicXchgOr:
case AtomicXchgSub:
case AtomicXchgXor:
case AtomicXchg:
return true;
default:
return false;
}
}
inline bool isAtomicCAS(Opcode opcode)
{
switch (opcode) {
case AtomicWeakCAS:
case AtomicStrongCAS:
return true;
default:
return false;
}
}
inline bool isAtomicXchg(Opcode opcode)
{
switch (opcode) {
case AtomicXchgAdd:
case AtomicXchgAnd:
case AtomicXchgOr:
case AtomicXchgSub:
case AtomicXchgXor:
case AtomicXchg:
return true;
default:
return false;
}
}
inline bool isMemoryAccess(Opcode opcode)
{
return isAtomic(opcode) || isLoadStore(opcode);
}
inline Opcode signExtendOpcode(Width width)
{
switch (width) {
case Width8:
return SExt8;
case Width16:
return SExt16;
default:
RELEASE_ASSERT_NOT_REACHED();
return Oops;
}
}
JS_EXPORT_PRIVATE Opcode storeOpcode(Bank bank, Width width);
} } // namespace JSC::B3
namespace WTF {
class PrintStream;
JS_EXPORT_PRIVATE void printInternal(PrintStream&, JSC::B3::Opcode);
} // namespace WTF
#endif // ENABLE(B3_JIT)