0N/A/*
2362N/A * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved.
0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0N/A *
0N/A * This code is free software; you can redistribute it and/or modify it
0N/A * under the terms of the GNU General Public License version 2 only, as
2362N/A * published by the Free Software Foundation. Oracle designates this
0N/A * particular file as subject to the "Classpath" exception as provided
2362N/A * by Oracle in the LICENSE file that accompanied this code.
0N/A *
0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
0N/A * You should have received a copy of the GNU General Public License version
0N/A * 2 along with this work; if not, write to the Free Software Foundation,
0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0N/A *
2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
2362N/A * or visit www.oracle.com if you need additional information or have any
2362N/A * questions.
0N/A */
0N/A
0N/Apackage sun.tools.tree;
0N/A
0N/Aimport sun.tools.java.*;
0N/Aimport sun.tools.asm.Assembler;
0N/Aimport sun.tools.asm.Label;
0N/Aimport java.io.PrintStream;
0N/Aimport java.util.Hashtable;
0N/A
0N/A/**
0N/A * WARNING: The contents of this source file are not part of any
0N/A * supported API. Code that depends on them does so at its own risk:
0N/A * they are subject to change or removal without notice.
0N/A */
0N/Apublic
0N/Aclass IfStatement extends Statement {
0N/A Expression cond;
0N/A Statement ifTrue;
0N/A Statement ifFalse;
0N/A
0N/A /**
0N/A * Constructor
0N/A */
0N/A public IfStatement(long where, Expression cond, Statement ifTrue, Statement ifFalse) {
0N/A super(IF, where);
0N/A this.cond = cond;
0N/A this.ifTrue = ifTrue;
0N/A this.ifFalse = ifFalse;
0N/A }
0N/A
0N/A /**
0N/A * Check statement
0N/A */
0N/A Vset check(Environment env, Context ctx, Vset vset, Hashtable exp) {
0N/A checkLabel(env, ctx);
0N/A CheckContext newctx = new CheckContext(ctx, this);
0N/A // Vset vsExtra = vset.copy(); // See comment below.
0N/A ConditionVars cvars =
0N/A cond.checkCondition(env, newctx, reach(env, vset), exp);
0N/A cond = convert(env, newctx, Type.tBoolean, cond);
0N/A // The following code, now deleted, was apparently an erroneous attempt
0N/A // at providing better error diagnostics. The comment read: 'If either
0N/A // the true clause or the false clause is unreachable, do a reasonable
0N/A // check on the child anyway.'
0N/A // Vset vsTrue = cvars.vsTrue.isDeadEnd() ? vsExtra : cvars.vsTrue;
0N/A // Vset vsFalse = cvars.vsFalse.isDeadEnd() ? vsExtra : cvars.vsFalse;
0N/A // Unfortunately, this violates the rules laid out in the JLS, and leads to
0N/A // blatantly incorrect results. For example, 'i' will not be recognized
0N/A // as definitely assigned following the statement 'if (true) i = 1;'.
0N/A // It is best to slavishly follow the JLS here. A cleverer approach could
0N/A // only correctly issue warnings, as JLS 16.2.6 is quite explicit, and it
0N/A // is OK for a dead branch of an if-statement to omit an assignment that
0N/A // would be required in the other branch. A complication: This code also
0N/A // had the effect of implementing the special-case rules for 'if-then' and
0N/A // 'if-then-else' in JLS 14.19, "Unreachable Statements". We now use
0N/A // 'Vset.clearDeadEnd' to remove the dead-end status of unreachable branches
0N/A // without affecting the definite-assignment status of the variables, thus
0N/A // maintaining a correct implementation of JLS 16.2.6. Fixes 4094353.
0N/A // Note that the code below will not consider the branches unreachable if
0N/A // the entire statement is unreachable. This is consistent with the error
0N/A // recovery policy that reports the only the first unreachable statement
0N/A // along an acyclic execution path.
0N/A Vset vsTrue = cvars.vsTrue.clearDeadEnd();
0N/A Vset vsFalse = cvars.vsFalse.clearDeadEnd();
0N/A vsTrue = ifTrue.check(env, newctx, vsTrue, exp);
0N/A if (ifFalse != null)
0N/A vsFalse = ifFalse.check(env, newctx, vsFalse, exp);
0N/A vset = vsTrue.join(vsFalse.join(newctx.vsBreak));
0N/A return ctx.removeAdditionalVars(vset);
0N/A }
0N/A
0N/A /**
0N/A * Inline
0N/A */
0N/A public Statement inline(Environment env, Context ctx) {
0N/A ctx = new Context(ctx, this);
0N/A cond = cond.inlineValue(env, ctx);
0N/A
0N/A // The compiler currently needs to perform inlining on both
0N/A // branches of the if statement -- even if `cond' is a constant
0N/A // true or false. Why? The compiler will later try to compile
0N/A // all classes that it has seen; this includes classes that
0N/A // appear in dead code. If we don't inline the dead branch here
0N/A // then the compiler will never perform inlining on any local
0N/A // classes appearing on the dead code. When the compiler tries
0N/A // to compile an un-inlined local class with uplevel references,
0N/A // it dies. (bug 4059492)
0N/A //
0N/A // A better solution to this would be to walk the dead branch and
0N/A // mark any local classes appearing therein as unneeded. Then the
0N/A // compilation phase could skip these classes.
0N/A if (ifTrue != null) {
0N/A ifTrue = ifTrue.inline(env, ctx);
0N/A }
0N/A if (ifFalse != null) {
0N/A ifFalse = ifFalse.inline(env, ctx);
0N/A }
0N/A if (cond.equals(true)) {
0N/A return eliminate(env, ifTrue);
0N/A }
0N/A if (cond.equals(false)) {
0N/A return eliminate(env, ifFalse);
0N/A }
0N/A if ((ifTrue == null) && (ifFalse == null)) {
0N/A return eliminate(env, new ExpressionStatement(where, cond).inline(env, ctx));
0N/A }
0N/A if (ifTrue == null) {
0N/A cond = new NotExpression(cond.where, cond).inlineValue(env, ctx);
0N/A return eliminate(env, new IfStatement(where, cond, ifFalse, null));
0N/A }
0N/A return this;
0N/A }
0N/A
0N/A /**
0N/A * Create a copy of the statement for method inlining
0N/A */
0N/A public Statement copyInline(Context ctx, boolean valNeeded) {
0N/A IfStatement s = (IfStatement)clone();
0N/A s.cond = cond.copyInline(ctx);
0N/A if (ifTrue != null) {
0N/A s.ifTrue = ifTrue.copyInline(ctx, valNeeded);
0N/A }
0N/A if (ifFalse != null) {
0N/A s.ifFalse = ifFalse.copyInline(ctx, valNeeded);
0N/A }
0N/A return s;
0N/A }
0N/A
0N/A /**
0N/A * The cost of inlining this statement
0N/A */
0N/A public int costInline(int thresh, Environment env, Context ctx) {
0N/A int cost = 1 + cond.costInline(thresh, env, ctx);
0N/A if (ifTrue != null) {
0N/A cost += ifTrue.costInline(thresh, env, ctx);
0N/A }
0N/A if (ifFalse != null) {
0N/A cost += ifFalse.costInline(thresh, env, ctx);
0N/A }
0N/A return cost;
0N/A }
0N/A
0N/A /**
0N/A * Code
0N/A */
0N/A public void code(Environment env, Context ctx, Assembler asm) {
0N/A CodeContext newctx = new CodeContext(ctx, this);
0N/A
0N/A Label l1 = new Label();
0N/A cond.codeBranch(env, newctx, asm, l1, false);
0N/A ifTrue.code(env, newctx, asm);
0N/A if (ifFalse != null) {
0N/A Label l2 = new Label();
0N/A asm.add(true, where, opc_goto, l2);
0N/A asm.add(l1);
0N/A ifFalse.code(env, newctx, asm);
0N/A asm.add(l2);
0N/A } else {
0N/A asm.add(l1);
0N/A }
0N/A
0N/A asm.add(newctx.breakLabel);
0N/A }
0N/A
0N/A /**
0N/A * Print
0N/A */
0N/A public void print(PrintStream out, int indent) {
0N/A super.print(out, indent);
0N/A out.print("if ");
0N/A cond.print(out);
0N/A out.print(" ");
0N/A ifTrue.print(out, indent);
0N/A if (ifFalse != null) {
0N/A out.print(" else ");
0N/A ifFalse.print(out, indent);
0N/A }
0N/A }
0N/A}