phaseX.hpp revision 948
/*
* Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
class Compile;
class ConINode;
class ConLNode;
class Node;
class Type;
class PhaseTransform;
class PhaseGVN;
class PhaseIterGVN;
class PhaseCCP;
class PhasePeephole;
class PhaseRegAlloc;
//-----------------------------------------------------------------------------
// Expandable closed hash-table of nodes, initialized to NULL.
// Note that the constructor just zeros things
// Storage is reclaimed when the Arena's lifetime is over.
protected:
public:
#ifdef ASSERT
~NodeHash(); // Unlock all nodes upon destruction of table.
void operator=(const NodeHash&); // Unlock all nodes upon replacement of table.
#endif
void check_grow() {
_inserts++;
}
void grow(); // Grow _table to next power of 2 and rehash
// Return 75% of _max, rounded up.
void clear(); // Set all entries to NULL, keep storage.
// Size of hash table
// Return Node* at index in table
return _table[table_index];
}
#ifndef PRODUCT
void dump(); // For debugging, dump statistics
#endif
};
//-----------------------------------------------------------------------------
// Map dense integer indices to Types. Uses classic doubling-array trick.
// Abstractly provides an infinite array of Type*'s, initialized to NULL.
// Note that the constructor just zeros things, and since I use Arena
// allocation I do not need a destructor to reclaim storage.
// Despite the general name, this class is customized for use by PhaseTransform.
class Type_Array : public StackObj {
friend class PhaseTransform;
public:
// Extend the mapping: index i maps to Type *n.
#ifndef PRODUCT
void dump() const;
#endif
};
//------------------------------PhaseRemoveUseless-----------------------------
// Remove useless nodes from GVN hash-table, worklist, and graph
class PhaseRemoveUseless : public Phase {
protected:
// list is allocated from current resource area
public:
};
//------------------------------PhaseTransform---------------------------------
// Phases that analyze, then transform. Constructing the Phase object does any
// global or slow analysis. The results are cached later for a fast
// transformation pass. When the Phase object is deleted the cached analysis
// results are deleted.
class PhaseTransform : public Phase {
protected:
// ConNode caches:
};
void init_con_caches();
// Support both int and long caches because either might be an intptr_t,
// so they show up frequently in address computations.
public:
// _nodes is used in varying ways by subclasses, which define local accessors
public:
// Get a previously recorded type for the node n.
// This type must already have been recorded.
// If you want the type of a very new (untransformed) node,
// you must use type_or_null, and test the result for NULL.
return t;
}
// Get a previously recorded type for the node n,
// or else return NULL if there is none.
}
// Record a type for a node.
}
// Record an initial type for a node, the node's bottom type.
void set_type_bottom(const Node* n) {
// Use this for initialization when bottom_type() (or better) is not handy.
// Usually the initialization shoudl be to n->Value(this) instead,
// or a hand-optimized value like Type::MEMORY or Type::CONTROL.
}
// Make sure the types array is big enough to record a size for the node n.
// (In product builds, we never want to do range checks on the types array!)
void ensure_type_or_null(const Node* n) {
}
// Utility functions:
const TypeInt* t = find_int_type(n);
}
const TypeLong* t = find_long_type(n);
}
// Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
// Same as transform(ConNode::make(t)).
{ ShouldNotCallThis(); return NULL; }
// Fast int or long constant. Same as TypeInt::make(i) or TypeLong::make(l).
// Fast zero or null constant. Same as makecon(Type::get_zero_type(bt)).
// Return a node which computes the same function as this node, but
// in a faster or cheaper fashion.
// Return whether two Nodes are equivalent.
// Must not be recursive, since the recursive version is built from this.
// For pessimistic optimizations this is simply pointer equivalence.
// Return whether two Nodes are equivalent, after stripping casting.
}
// For pessimistic passes, the return type must monotonically narrow.
// For optimistic passes, the return type must monotonically widen.
// It is possible to get into a "death march" in either type of pass,
// where the types are continually moving but it will take 2**31 or
// more steps to converge. This doesn't happen on most normal loops.
//
// Here is an example of a deadly loop for an optimistic pass, along
// with a partial trace of inferred types:
// x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
// 0 1 join([0..max], 1)
// [0..1] [1..2] join([0..max], [1..2])
// [0..2] [1..3] join([0..max], [1..3])
// ... ... ...
// [0..max] [min]u[1..max] join([0..max], [min..max])
// [0..max] ==> fixpoint
// We would have proven, the hard way, that the iteration space is all
// non-negative ints, with the loop terminating due to 32-bit overflow.
//
// Here is the corresponding example for a pessimistic pass:
// x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
// int int join([0..max], int)
// [0..max] [-1..max-1] join([0..max], [-1..max-1])
// [0..max-1] [-1..max-2] join([0..max], [-1..max-2])
// ... ... ...
// [0..1] [-1..0] join([0..max], [-1..0])
// 0 -1 join([0..max], -1)
// 0 == fixpoint
// We would have proven, the hard way, that the iteration space is {0}.
// (Usually, other optimizations will make the "if (x >= 0)" fold up
// before we get into trouble. But not always.)
//
// It's a pleasant thing to observe that the pessimistic pass
// will make short work of the optimistic pass's deadly loop,
// and vice versa. That is a good example of the complementary
// purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
//
// In any case, only widen or narrow a few times before going to the
// correct flavor of top or bottom.
//
// This call only needs to be made once as the data flows around any
// given cycle. We do it at Phis, and nowhere else.
// The types presented are the new type of a phi (computed by PhiNode::Value)
// and the previously computed type, last time the phi was visited.
//
// The third argument is upper limit for the saturated value,
// if the phase wishes to widen the new_type.
// If the phase is narrowing, the old type provides a lower limit.
// Caller guarantees that old_type and new_type are no higher than limit_type.
const Type* limit_type) const
{ ShouldNotCallThis(); return NULL; }
#ifndef PRODUCT
void dump_old2new_map() const;
void dump_types() const;
void set_progress() { ++_count_progress; assert( allow_progress(),"No progress allowed during verification") }
void clear_progress() { _count_progress = 0; }
void set_transforms() { ++_count_transforms; }
void clear_transforms() { _count_transforms = 0; }
bool _allow_progress; // progress not allowed during verification pass
bool allow_progress() { return _allow_progress; }
#endif
};
//------------------------------PhaseValues------------------------------------
// Phase infrastructure to support values
class PhaseValues : public PhaseTransform {
protected:
public:
NOT_PRODUCT( ~PhaseValues(); )
virtual PhaseIterGVN *is_IterGVN() { return 0; }
// Some Ideal and other transforms delete --> modify --> insert values
// Used after parsing to eliminate values that are no longer in program
const Type* limit_type) const
{ return new_type; }
#ifndef PRODUCT
void inc_new_values() { ++_count_new_values; }
void clear_new_values() { _count_new_values = 0; }
#endif
};
//------------------------------PhaseGVN---------------------------------------
// Phase for performing local, pessimistic GVN-style optimizations.
class PhaseGVN : public PhaseValues {
public:
// Return a node which computes the same function as this node, but
// in a faster or cheaper fashion.
// Check for a simple dead loop when a data node references itself.
};
//------------------------------PhaseIterGVN-----------------------------------
// Phase for iteratively performing local, pessimistic GVN-style optimizations.
// and ideal transformations on the graph.
class PhaseIterGVN : public PhaseGVN {
private:
bool _delay_transform; // When true simply register the node when calling transform
// instead of actually optimizing it
// Idealize old Node 'n' with respect to its inputs and its value
protected:
// Idealize new Node 'n' with respect to its inputs and its value
// Warm up hash table, type table and initial worklist
const Type* limit_type) const;
// Usually returns new_type. Returns old_type if new_type is only a slight
// improvement, such that it would take many (>>10) steps to reach 2**32.
public:
virtual PhaseIterGVN *is_IterGVN() { return this; }
// Given def-use info and an initial worklist, apply Node::Ideal,
// Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
// and dominator info to a fixed point.
void optimize();
// Register a new node with the iter GVN pass without transforming it.
// and Phis need to complete this one big transform before any other
// transforms can be triggered on the region.
// Optional 'orig' is an earlier version of this node.
// It is significant only for debugging and profiling.
// Kill a globally dead Node. It is allowed to have uses which are
// assumed dead and left 'in limbo'.
// Kill all inputs to a dead node, recursively making more dead nodes.
// The Node must be dead locally, i.e., have no uses.
}
// Subsume users of node 'old' into node 'nn'
// If no Def-Use info existed for 'nn' it will after call.
// Add users of 'n' to worklist
void add_users_to_worklist0( Node *n );
void add_users_to_worklist ( Node *n );
// Replace old node with new one.
}
bool delay_transform() const { return _delay_transform; }
void set_delay_transform(bool delay) {
}
#ifndef PRODUCT
protected:
// Sub-quadratic implementation of VerifyIterativeGVN.
unsigned long _verify_counter;
unsigned long _verify_full_passes;
enum { _verify_window_size = 30 };
void verify_step(Node* n);
#endif
};
//------------------------------PhaseCCP---------------------------------------
// Phase for performing global Conditional Constant Propagation.
// Should be replaced with combined CCP & GVN someday.
class PhaseCCP : public PhaseIterGVN {
// Non-recursive. Use analysis to transform single Node.
public:
NOT_PRODUCT( ~PhaseCCP(); )
// Worklist algorithm identifies constants
void analyze();
// Recursive traversal of program. Used analysis to modify program.
// Do any transformation after analysis
void do_transform();
const Type* limit_type) const;
// Returns new_type->widen(old_type), which increments the widen bits until
// giving up with TypeInt::INT or TypeLong::LONG.
// Result is clipped to limit_type if necessary.
#ifndef PRODUCT
void clear_constants() { _count_constants = 0; }
void inc_constants() { ++_count_constants; }
static void print_statistics();
#endif
};
//------------------------------PhasePeephole----------------------------------
// Phase for performing peephole optimizations on register allocated basic blocks.
class PhasePeephole : public PhaseTransform {
// Recursive traversal of program. Pure function is unused in this phase
public:
NOT_PRODUCT( ~PhasePeephole(); )
// Do any transformation after analysis
void do_transform();
#ifndef PRODUCT
void clear_peepholes() { _count_peepholes = 0; }
void inc_peepholes() { ++_count_peepholes; }
static void print_statistics();
#endif
};