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?
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,
