On April 14, 2015 1:36:14 AM GMT+02:00, Jan Hubicka <hubi...@ucw.cz> wrote:
>Hi,
>while looking on a testcase, i noticed that for simple code
>
> if (param > 6.0)
> BB1;
> else
> BB2;
>the inline predicates currectly determine (param > 6.0) predicate
>for BB1, but they give (true) predicate to BB2 unless
>-fno-trapping-math is
>specified. This is because invert_tree_comparison returns ERROR_MARK
>when called with HONOR_NANS.
>
>I see that this is most likely to preserve trappingness of the
>comparsion
>- UNLE that is a logcial negative won't report unordered. For my use
>it is
>however save to use (param UNLE 6.0) as predicate for BB2 as I do not
>really
>care if the conditional will trap. The inline predicates just need to
>be
>conservative with respect to real program behaviour.
>I can not pass HONOR_NANS=false because then the BB2 predicate would
>be (param <= 6.0) and that would allow inliner to assume that for
>param == UNORDERED both code paths are unreachable.
>
>This patch adds extra paremter to invert_tree_comparsion to do what I
>want.
>Does it seem sane?
Don't you have to default CONSIDER_TRAP to true to retain previous behaviour
for e.g. fold_truth_not_expr and other users that pass down HONOR_NANS to
honour_nans?
Thanks,
>
>Honza
>
> * fold-const.c (invert_tree_comparison): Add CONSIDER_TRAP.
> * fold-const.h (invert_tree_comparison): Update prototype.
> * ipa-inline-analysis.c (add_clause): Update use
> of invert_tree_comparsoin
> (set_cond_stmt_execution_predicate): Likewise.
>Index: fold-const.c
>===================================================================
>--- fold-const.c (revision 222052)
>+++ fold-const.c (working copy)
>@@ -2436,13 +2436,17 @@ pedantic_non_lvalue_loc (location_t loc,
>/* Given a tree comparison code, return the code that is the logical
>inverse.
>It is generally not safe to do this for floating-point comparisons,
>except
> for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
>- ERROR_MARK in this case. */
>+ ERROR_MARK in this case.
>+
>+ if CONSDIER_TRAP is false, do not really care about the case when
>+ conditional expression may trap. */
>
> enum tree_code
>-invert_tree_comparison (enum tree_code code, bool honor_nans)
>+invert_tree_comparison (enum tree_code code, bool honor_nans,
>+ bool consider_trap)
> {
>- if (honor_nans && flag_trapping_math && code != EQ_EXPR && code !=
>NE_EXPR
>- && code != ORDERED_EXPR && code != UNORDERED_EXPR)
>+ if (honor_nans && consider_trap && flag_trapping_math && code !=
>EQ_EXPR
>+ && code != NE_EXPR && code != ORDERED_EXPR && code !=
>UNORDERED_EXPR)
> return ERROR_MARK;
>
> switch (code)
>Index: fold-const.h
>===================================================================
>--- fold-const.h (revision 222052)
>+++ fold-const.h (working copy)
>@@ -126,7 +126,8 @@ extern bool tree_swap_operands_p (const_
> extern enum tree_code swap_tree_comparison (enum tree_code);
>
> extern bool ptr_difference_const (tree, tree, HOST_WIDE_INT *);
>-extern enum tree_code invert_tree_comparison (enum tree_code, bool);
>+extern enum tree_code invert_tree_comparison (enum tree_code, bool,
>+ bool consider_trap = false);
>
>extern bool tree_unary_nonzero_warnv_p (enum tree_code, tree, tree,
>bool *);
>extern bool tree_binary_nonzero_warnv_p (enum tree_code, tree, tree,
>tree op1,
>Index: ipa-inline-analysis.c
>===================================================================
>--- ipa-inline-analysis.c (revision 222052)
>+++ ipa-inline-analysis.c (working copy)
>@@ -381,7 +381,8 @@ add_clause (conditions conditions, struc
> && cc2->code != IS_NOT_CONSTANT
> && cc2->code != CHANGED
> && cc1->code == invert_tree_comparison (cc2->code,
>- HONOR_NANS (cc1->val)))
>+ HONOR_NANS (cc1->val),
>+ false))
> return;
> }
> }
>@@ -1798,15 +1799,13 @@ set_cond_stmt_execution_predicate (struc
>if (unmodified_parm_or_parm_agg_item (info, last, op, &index, &aggpos))
> {
> code = gimple_cond_code (last);
>- inverted_code = invert_tree_comparison (code, HONOR_NANS (op));
>+ inverted_code = invert_tree_comparison (code, HONOR_NANS (op),
>false);
>
> FOR_EACH_EDGE (e, ei, bb->succs)
> {
> enum tree_code this_code = (e->flags & EDGE_TRUE_VALUE
> ? code : inverted_code);
>- /* invert_tree_comparison will return ERROR_MARK on FP
>- comparsions that are not EQ/NE instead of returning proper
>- unordered one. Be sure it is not confused with NON_CONSTANT.
>*/
>+ /* Be sure to not confuse ERROR_MARK with NON_CONSTANT. */
> if (this_code != ERROR_MARK)
> {
> struct predicate p = add_condition (summary, index, &aggpos,
