* [Ada] Optization of predicate checks
@ 2015-10-16 12:33 Arnaud Charlet
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From: Arnaud Charlet @ 2015-10-16 12:33 UTC (permalink / raw)
To: gcc-patches; +Cc: Ed Schonberg
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This patch marks the generated predicate functions as Pure, so that the
back-end can optimize redundant calls to these functions when inlining and
high level of optimization are requested.
This is a performance enhancement, no change in behavior.
Tested on x86_64-pc-linux-gnu, committed on trunk
2015-10-16 Ed Schonberg <schonberg@adacore.com>
* sem_ch13.adb (Build_Predicate_Functions): If expression for
predicate is side-effect free, indicate that the predicate
function is pure, to allow for optimization of redundant
predicate checks.
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Index: sem_ch13.adb
===================================================================
--- sem_ch13.adb (revision 228874)
+++ sem_ch13.adb (working copy)
@@ -8702,6 +8702,16 @@
Insert_Before_And_Analyze (N, FDecl);
Insert_After_And_Analyze (N, FBody);
+
+ -- Static predicate functions are always side-effect free, and
+ -- in most cases dynamic predicate functions are as well. Mark
+ -- them as such whenever possible, so redundant predicate checks
+ -- can be optimized.
+
+ if Expander_Active then
+ Set_Is_Pure (SId, Side_Effect_Free (Expr));
+ Set_Is_Inlined (SId);
+ end if;
end;
-- Test for raise expressions present and if so build M version
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