tree-cfg.c (find_taken_edge): Statically compute the truth value of a predicate comparing an SSA_NAME to itself.
* tree-cfg.c (find_taken_edge): Statically compute the truth value of a predicate comparing an SSA_NAME to itself. From-SVN: r84561
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2004-07-12 Diego Novillo <dnovillo@redhat.com>
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* tree-cfg.c (find_taken_edge): Statically compute the truth
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value of a predicate comparing an SSA_NAME to itself.
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2004-07-12 Roger Sayle <roger@eyesopen.com>
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* config/rs6000/rs6000.c (rs6000_rtx_costs): Indicate that the
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@ -1991,9 +1991,9 @@ cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi)
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}
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/* Given a control block BB and a constant value VAL, return the edge that
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will be taken out of the block. If VAL does not match a unique edge,
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NULL is returned. */
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/* Given a control block BB and a predicate VAL, return the edge that
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will be taken out of the block. If VAL does not match a unique
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edge, NULL is returned. */
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edge
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find_taken_edge (basic_block bb, tree val)
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@ -2007,6 +2007,24 @@ find_taken_edge (basic_block bb, tree val)
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abort ();
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#endif
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/* If VAL is a predicate of the form N RELOP N, where N is an
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SSA_NAME, we can always determine its truth value (except when
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doing floating point comparisons that may involve NaNs). */
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if (val
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&& TREE_CODE_CLASS (TREE_CODE (val)) == '<'
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&& TREE_OPERAND (val, 0) == TREE_OPERAND (val, 1)
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&& TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME
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&& (TREE_CODE (TREE_TYPE (TREE_OPERAND (val, 0))) != REAL_TYPE
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|| !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val, 0))))))
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{
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enum tree_code code = TREE_CODE (val);
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if (code == EQ_EXPR || code == LE_EXPR || code == GE_EXPR)
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val = boolean_true_node;
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else if (code == LT_EXPR || code == GT_EXPR || code == NE_EXPR)
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val = boolean_false_node;
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}
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/* If VAL is not a constant, we can't determine which edge might
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be taken. */
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if (val == NULL || !really_constant_p (val))
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