SSATmp* IRBuilder::preOptimizeCheckStk(IRInstruction* inst) { auto const newType = inst->typeParam(); auto sp = inst->src(0); auto offset = inst->extra<CheckStk>()->offset; auto stkVal = getStackValue(sp, offset); auto const oldType = stkVal.knownType; if (oldType.isBoxed() && newType.isBoxed() && (oldType.not(newType) || newType < oldType)) { /* This CheckStk serves to update the inner type hint for a boxed * value, which requires no runtime work. This depends on the type being * boxed, and constraining it with DataTypeCountness will do it. */ constrainStack(sp, offset, DataTypeCountness); return gen(AssertStk, newType, StackOffset(offset), sp); } if (newType.not(oldType)) { /* This check will always fail. It's probably due to an incorrect * prediction. Generate a Jmp, and return the source because * following instructions may depend on the output of CheckStk * (they'll be DCEd later). Note that we can't use convertToJmp * because the return value isn't nullptr, so the original * instruction won't be inserted into the stream. */ gen(Jmp, inst->taken()); return sp; } if (newType >= oldType) { // The new type isn't better than the old type. return sp; } return nullptr; }
/** * Trace back to the guard that provided the type of val, if * any. Constrain it so its type will not be relaxed beyond the given * DataTypeCategory. Always returns val, for convenience. */ SSATmp* TraceBuilder::constrainValue(SSATmp* const val, DataTypeCategory cat) { if (!val) { FTRACE(1, "constrainValue(nullptr, {}), bailing\n", cat); return nullptr; } FTRACE(1, "constrainValue({}, {})\n", *val->inst(), cat); // If cat is DataTypeGeneric, there's nothing to do. if (cat == DataTypeGeneric) return val; auto inst = val->inst(); if (inst->op() == LdLoc || inst->op() == LdLocAddr) { // We've hit a LdLoc(Addr). If the source of the value is non-null and not // a FramePtr, it's a real value that was killed by a Call. The value won't // be live but it's ok to use it to track down the guard. auto source = inst->extra<LdLocData>()->valSrc; if (!source) { // val was newly created in this trace. Nothing to constrain. FTRACE(2, " - valSrc is null, bailing\n"); return val; } // If valSrc is a FramePtr, it represents the frame the value was // originally loaded from. Look for the guard for this local. if (source->isA(Type::FramePtr)) { constrainLocal(inst->extra<LocalId>()->locId, source, cat, "constrainValue"); return val; } // Otherwise, keep chasing down the source of val. constrainValue(source, cat); } else if (inst->op() == LdStack) { constrainStack(inst->src(0), inst->extra<StackOffset>()->offset, cat); } else if (inst->op() == CheckType) { // Constrain this CheckType and keep going on its source value, in case // there are more guards to constrain. constrainGuard(inst, cat); constrainValue(inst->src(0), cat); } else if (inst->op() == StRef || inst->op() == StRefNT) { // TODO(t2598894): This can be tightened up. As a conservative // approximation, pass the constraint through to the source of the value. constrainValue(inst->src(1), cat); } else if (inst->isPassthrough()) { constrainValue(inst->getPassthroughValue(), cat); } else { // Any instructions not special cased above produce a new value, so // there's no guard for us to constrain. FTRACE(2, " - value is new in this trace, bailing\n"); } return val; }
SSATmp* IRBuilder::preOptimizeAssertStk(IRInstruction* inst) { auto const idx = inst->extra<AssertStk>()->offset; auto const info = getStackValue(inst->src(0), idx); return preOptimizeAssertTypeOp(inst, info.knownType, [&](TypeConstraint tc) { constrainStack(inst->src(0), idx, tc); } ); }
bool IRBuilder::constrainStack(int32_t idx, TypeConstraint tc) { if (!shouldConstrainGuards()) return false; return constrainStack(sp(), idx, tc); }
/** * Trace back to the guard that provided the type of val, if * any. Constrain it so its type will not be relaxed beyond the given * DataTypeCategory. Returns true iff one or more guard instructions * were constrained. */ bool IRBuilder::constrainValue(SSATmp* const val, TypeConstraint tc) { if (!shouldConstrainGuards()) return false; if (!val) { FTRACE(1, "constrainValue(nullptr, {}), bailing\n", tc); return false; } FTRACE(1, "constrainValue({}, {})\n", *val->inst(), tc); auto inst = val->inst(); if (inst->is(LdLoc, LdLocAddr)) { // We've hit a LdLoc(Addr). If the source of the value is non-null and not // a FramePtr, it's a real value that was killed by a Call. The value won't // be live but it's ok to use it to track down the guard. auto source = inst->extra<LocalData>()->typeSrc; if (!source) { // val was newly created in this trace. Nothing to constrain. FTRACE(2, " - typeSrc is null, bailing\n"); return false; } // If valSrc is a FramePtr, it represents the frame the value was // originally loaded from. Look for the guard for this local. if (source->isA(Type::FramePtr)) { return constrainLocal(inst->extra<LocalId>()->locId, source, tc, "constrainValue"); } // Otherwise, keep chasing down the source of val. return constrainValue(source, tc); } else if (inst->is(LdStack, LdStackAddr)) { return constrainStack(inst->src(0), inst->extra<StackOffset>()->offset, tc); } else if (inst->is(CheckType, AssertType)) { // If the dest type of the instruction fits the constraint we want, we can // stop here without constraining any further. Otherwise, continue through // to the source. auto changed = false; if (inst->is(CheckType)) changed = constrainGuard(inst, tc) || changed; auto dstType = inst->typeParam(); if (!typeFitsConstraint(dstType, tc.category)) { changed = constrainValue(inst->src(0), tc) || changed; } return changed; } else if (inst->is(StRef)) { // StRef requires that src(0) is boxed so we're relying on callers to // appropriately constrain the values they pass to it. Any innerCat in tc // should be applied to the value being stored. tc.category = tc.innerCat; tc.innerCat = DataTypeGeneric; tc.assertedType = Type::Gen; return constrainValue(inst->src(1), tc); } else if (inst->is(Box, BoxPtr, Unbox, UnboxPtr)) { // All Box/Unbox opcodes are similar to StRef/LdRef in some situations and // Mov in others (determined at runtime), so we need to constrain both // outer and inner. auto maxCat = std::max(tc.category, tc.innerCat); tc.category = maxCat; tc.innerCat = maxCat; tc.assertedType = Type::Gen; return constrainValue(inst->src(0), tc); } else if (inst->is(LdRef)) { // Like StRef, we're relying on the caller to have appropriately // constrained the outer type of the box. Constrain the inner type of the // box with tc. tc.innerCat = tc.category; tc.category = DataTypeGeneric; tc.assertedType = Type::Gen; return constrainValue(inst->src(0), tc); } else if (inst->isPassthrough()) { return constrainValue(inst->getPassthroughValue(), tc); } else { // Any instructions not special cased above produce a new value, so // there's no guard for us to constrain. FTRACE(2, " - value is new in this trace, bailing\n"); return false; } // TODO(t2598894): Should be able to do something with LdMem<T> here }
bool TraceBuilder::constrainStack(int32_t idx, TypeConstraint tc) { return constrainStack(sp(), idx, tc); }
/** * Trace back to the guard that provided the type of val, if * any. Constrain it so its type will not be relaxed beyond the given * DataTypeCategory. Returns true iff one or more guard instructions * were constrained. */ bool TraceBuilder::constrainValue(SSATmp* const val, TypeConstraint tc) { if (!shouldConstrainGuards()) return false; if (!val) { FTRACE(1, "constrainValue(nullptr, {}), bailing\n", tc); return false; } FTRACE(1, "constrainValue({}, {})\n", *val->inst(), tc); auto inst = val->inst(); if (inst->is(LdLoc, LdLocAddr)) { // We've hit a LdLoc(Addr). If the source of the value is non-null and not // a FramePtr, it's a real value that was killed by a Call. The value won't // be live but it's ok to use it to track down the guard. auto source = inst->extra<LocalData>()->valSrc; if (!source) { // val was newly created in this trace. Nothing to constrain. FTRACE(2, " - valSrc is null, bailing\n"); return false; } // If valSrc is a FramePtr, it represents the frame the value was // originally loaded from. Look for the guard for this local. if (source->isA(Type::FramePtr)) { return constrainLocal(inst->extra<LocalId>()->locId, source, tc, "constrainValue"); } // Otherwise, keep chasing down the source of val. return constrainValue(source, tc); } else if (inst->is(LdStack, LdStackAddr)) { return constrainStack(inst->src(0), inst->extra<StackOffset>()->offset, tc); } else if (inst->is(CheckType, AssertType)) { // If the dest type of the instruction fits the constraint we want, we can // stop here without constraining any further. Otherwise, continue through // to the source. auto changed = false; if (inst->is(CheckType)) changed = constrainGuard(inst, tc) || changed; auto dstType = inst->typeParam(); if (!typeFitsConstraint(dstType, tc.category)) { changed = constrainValue(inst->src(0), tc) || changed; } return changed; } else if (inst->is(StRef, StRefNT, Box, BoxPtr)) { // If our caller cares about the inner type, propagate that through. // Otherwise we're done. if (tc.innerCat) { auto src = inst->src(inst->is(StRef, StRefNT) ? 1 : 0); tc.innerCat.reset(); return constrainValue(src, tc); } return false; } else if (inst->is(LdRef, Unbox, UnboxPtr)) { // Pass through to the source of the box, remembering that we care about // the inner type of the box. assert(!tc.innerCat); tc.innerCat = tc.category; return constrainValue(inst->src(0), tc); } else if (inst->isPassthrough()) { return constrainValue(inst->getPassthroughValue(), tc); } else { // Any instructions not special cased above produce a new value, so // there's no guard for us to constrain. FTRACE(2, " - value is new in this trace, bailing\n"); return false; } // TODO(t2598894): Should be able to do something with LdMem<T> here }
void TraceBuilder::constrainStack(int32_t idx, TypeConstraint tc) { constrainStack(sp(), idx, tc); }
/** * Trace back to the guard that provided the type of val, if * any. Constrain it so its type will not be relaxed beyond the given * DataTypeCategory. Returns true iff one or more guard instructions * were constrained. */ bool IRBuilder::constrainValue(SSATmp* const val, TypeConstraint tc) { if (!shouldConstrainGuards()) return false; always_assert(IMPLIES(tc.innerCat > DataTypeGeneric, tc.category >= DataTypeCountness)); if (!val) { ITRACE(1, "constrainValue(nullptr, {}), bailing\n", tc); return false; } ITRACE(1, "constrainValue({}, {})\n", *val->inst(), tc); Indent _i; auto inst = val->inst(); if (inst->is(LdLoc, LdLocAddr)) { // We've hit a LdLoc(Addr). If the source of the value is non-null and not // a FramePtr, it's a real value that was killed by a Call. The value won't // be live but it's ok to use it to track down the guard. auto source = inst->extra<LocalData>()->typeSrc; if (!source) { // val was newly created in this trace. Nothing to constrain. ITRACE(2, "typeSrc is null, bailing\n"); return false; } // If typeSrc is a FramePtr, it represents the frame the value was // originally loaded from. Look for the guard for this local. if (source->isA(Type::FramePtr)) { return constrainLocal(inst->extra<LocalId>()->locId, source, tc, "constrainValue"); } // Otherwise, keep chasing down the source of val. return constrainValue(source, tc); } else if (inst->is(LdStack, LdStackAddr)) { return constrainStack(inst->src(0), inst->extra<StackOffset>()->offset, tc); } else if (inst->is(AssertType)) { // Sometimes code in HhbcTranslator asks for a value with DataTypeSpecific // but can tolerate a less specific value. If that happens, there's nothing // to constrain. if (!typeFitsConstraint(val->type(), tc)) return false; // If the immutable typeParam fits the constraint, we're done. auto const typeParam = inst->typeParam(); if (typeFitsConstraint(typeParam, tc)) return false; auto const newTc = relaxConstraint(tc, typeParam, inst->src(0)->type()); ITRACE(1, "tracing through {}, orig tc: {}, new tc: {}\n", *inst, tc, newTc); return constrainValue(inst->src(0), newTc); } else if (inst->is(CheckType)) { // Sometimes code in HhbcTranslator asks for a value with DataTypeSpecific // but can tolerate a less specific value. If that happens, there's nothing // to constrain. if (!typeFitsConstraint(val->type(), tc)) return false; bool changed = false; auto const typeParam = inst->typeParam(); auto const srcType = inst->src(0)->type(); // Constrain the guard on the CheckType, but first relax the constraint // based on what's known about srcType. auto const guardTc = relaxConstraint(tc, srcType, typeParam); changed = constrainGuard(inst, guardTc) || changed; // Relax typeParam with its current constraint. This is used below to // recursively relax the constraint on the source, if needed. auto constraint = m_guardConstraints[inst]; constraint.category = std::max(constraint.category, guardTc.category); constraint.innerCat = std::max(constraint.innerCat, guardTc.innerCat); auto const knownType = refineType(relaxType(typeParam, constraint), constraint.assertedType); if (!typeFitsConstraint(knownType, tc)) { auto const newTc = relaxConstraint(tc, knownType, srcType); ITRACE(1, "tracing through {}, orig tc: {}, new tc: {}\n", *inst, tc, newTc); changed = constrainValue(inst->src(0), newTc) || changed; } return changed; } else if (inst->is(StRef)) { // StRef requires that src(0) is boxed so we're relying on callers to // appropriately constrain the values they pass to it. Any innerCat in tc // should be applied to the value being stored. tc.category = tc.innerCat; tc.innerCat = DataTypeGeneric; tc.assertedType = Type::Gen; return constrainValue(inst->src(1), tc); } else if (inst->is(Box, BoxPtr, Unbox, UnboxPtr)) { // All Box/Unbox opcodes are similar to StRef/LdRef in some situations and // Mov in others (determined at runtime), so we need to constrain both // outer and inner. auto maxCat = std::max(tc.category, tc.innerCat); tc.category = maxCat; tc.innerCat = maxCat; tc.assertedType = Type::Gen; return constrainValue(inst->src(0), tc); } else if (inst->is(LdRef)) { // Constrain the inner type of the box with tc, using DataTypeCountness for // the outer constraint to preserve the fact that it's a box. tc.innerCat = tc.category; tc.category = DataTypeCountness; tc.assertedType = Type::Gen; return constrainValue(inst->src(0), tc); } else if (inst->isPassthrough()) { return constrainValue(inst->getPassthroughValue(), tc); } else { // Any instructions not special cased above produce a new value, so // there's no guard for us to constrain. ITRACE(2, "value is new in this trace, bailing\n"); return false; } // TODO(t2598894): Should be able to do something with LdMem<T> here }
bool IRBuilder::constrainStack(SSATmp* sp, int32_t idx, TypeConstraint tc) { if (!shouldConstrainGuards()) return false; always_assert(IMPLIES(tc.innerCat > DataTypeGeneric, tc.category >= DataTypeCountness)); ITRACE(1, "constrainStack({}, {}, {})\n", *sp->inst(), idx, tc); Indent _i; assert(sp->isA(Type::StkPtr)); // We've hit a LdStack. If getStackValue gives us a value, recurse on // that. Otherwise, look at the instruction that gave us the type of the // stack element. If it's a GuardStk or CheckStk, it's our target. If it's // anything else, the value is new so there's no guard to relax. auto stackInfo = getStackValue(sp, idx); // Sometimes code in HhbcTranslator asks for a value with DataTypeSpecific // but can tolerate a less specific value. If that happens, there's nothing // to constrain. if (!typeFitsConstraint(stackInfo.knownType, tc)) return false; IRInstruction* typeSrc = stackInfo.typeSrc; if (stackInfo.value) { ITRACE(1, "value = {}\n", *stackInfo.value->inst()); return constrainValue(stackInfo.value, tc); } else if (typeSrc->is(AssertStk)) { // If the immutable typeParam fits the constraint, we're done. auto const typeParam = typeSrc->typeParam(); if (typeFitsConstraint(typeParam, tc)) return false; auto const srcIdx = typeSrc->extra<StackOffset>()->offset; auto const srcType = getStackValue(typeSrc->src(0), srcIdx).knownType; auto const newTc = relaxConstraint(tc, typeParam, srcType); ITRACE(1, "tracing through {}, orig tc: {}, new tc: {}\n", *typeSrc, tc, newTc); return constrainStack(typeSrc->src(0), srcIdx, newTc); } else if (typeSrc->is(CheckStk)) { auto changed = false; auto const typeParam = typeSrc->typeParam(); auto const srcIdx = typeSrc->extra<StackOffset>()->offset; auto const srcType = getStackValue(typeSrc->src(0), srcIdx).knownType; // Constrain the guard on the CheckType, but first relax the constraint // based on what's known about srcType. auto const guardTc = relaxConstraint(tc, srcType, typeParam); changed = constrainGuard(typeSrc, guardTc) || changed; // Relax typeParam with its current constraint. This is used below to // recursively relax the constraint on the source, if needed. auto constraint = m_guardConstraints[typeSrc]; constraint.category = std::max(constraint.category, guardTc.category); constraint.innerCat = std::max(constraint.innerCat, guardTc.innerCat); auto const knownType = refineType(relaxType(typeParam, constraint), constraint.assertedType); if (!typeFitsConstraint(knownType, tc)) { auto const newTc = relaxConstraint(tc, knownType, srcType); ITRACE(1, "tracing through {}, orig tc: {}, new tc: {}\n", *typeSrc, tc, newTc); changed = constrainStack(typeSrc->src(0), srcIdx, newTc) || changed; } return changed; } else { ITRACE(1, "typeSrc = {}\n", *typeSrc); return typeSrc->is(GuardStk) && constrainGuard(typeSrc, tc); } }
void TraceBuilder::constrainStack(int32_t idx, DataTypeCategory cat) { constrainStack(sp(), idx, cat); }