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This commit is contained in:
Vladimir Kozlov 2009-03-19 09:13:24 -07:00
commit 41463d1d3a
81 changed files with 2355 additions and 948 deletions
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22
hotspot/src/share/vm/opto/graphKit.cpp
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@ -2277,7 +2277,7 @@ Node* GraphKit::gen_subtype_check(Node* subklass, Node* superklass) {
r_not_subtype->init_req(1, _gvn.transform( new (C, 1) IfTrueNode (iff2) ) );
set_control( _gvn.transform( new (C, 1) IfFalseNode(iff2) ) );
// Check for self. Very rare to get here, but its taken 1/3 the time.
// Check for self. Very rare to get here, but it is taken 1/3 the time.
// No performance impact (too rare) but allows sharing of secondary arrays
// which has some footprint reduction.
Node *cmp3 = _gvn.transform( new (C, 3) CmpPNode( subklass, superklass ) );
@ -2286,11 +2286,27 @@ Node* GraphKit::gen_subtype_check(Node* subklass, Node* superklass) {
r_ok_subtype->init_req(2, _gvn.transform( new (C, 1) IfTrueNode ( iff3 ) ) );
set_control( _gvn.transform( new (C, 1) IfFalseNode( iff3 ) ) );
// -- Roads not taken here: --
// We could also have chosen to perform the self-check at the beginning
// of this code sequence, as the assembler does. This would not pay off
// the same way, since the optimizer, unlike the assembler, can perform
// static type analysis to fold away many successful self-checks.
// Non-foldable self checks work better here in second position, because
// the initial primary superclass check subsumes a self-check for most
// types. An exception would be a secondary type like array-of-interface,
// which does not appear in its own primary supertype display.
// Finally, we could have chosen to move the self-check into the
// PartialSubtypeCheckNode, and from there out-of-line in a platform
// dependent manner. But it is worthwhile to have the check here,
// where it can be perhaps be optimized. The cost in code space is
// small (register compare, branch).
// Now do a linear scan of the secondary super-klass array. Again, no real
// performance impact (too rare) but it's gotta be done.
// (The stub also contains the self-check of subklass == superklass.
// Since the code is rarely used, there is no penalty for moving it
// out of line, and it can only improve I-cache density.)
// out of line, and it can only improve I-cache density.
// The decision to inline or out-of-line this final check is platform
// dependent, and is found in the AD file definition of PartialSubtypeCheck.
Node* psc = _gvn.transform(
new (C, 3) PartialSubtypeCheckNode(control(), subklass, superklass) );