From: Steve Baird <baird@adacore.com>
Date: Tue, 27 Feb 2024 20:11:47 +0000 (-0800)
Subject: ada: Redundant validity checks
X-Git-Tag: basepoints/gcc-16~8985
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=584ade0b82339d95463bc91c9fdd77579b16426a;p=thirdparty%2Fgcc.git

ada: Redundant validity checks

In some cases with validity checking enabled via the -gnatVa option,
the compiler generates validity checks that can (obviously) never fail.
These include validity checks for (some) static expressions, and consecutive
identical checks generated for a single read of an object.

gcc/ada/

	* checks.adb (Expr_Known_Valid): Return True for a static expression.
	* exp_util.adb (Adjust_Condition): No validity check needed for a
	condition if it is an expression for which a validity check has
	already been generated.
---

diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb
index 6af392eeda8..bada3dffcbf 100644
--- a/gcc/ada/checks.adb
+++ b/gcc/ada/checks.adb
@@ -6839,6 +6839,9 @@ package body Checks is
       then
          return True;
 
+      elsif Is_Static_Expression (Expr) then
+         return True;
+
       --  If the expression is the value of an object that is known to be
       --  valid, then clearly the expression value itself is valid.
 
diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
index 057cf3ebc48..b71f7739481 100644
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -416,6 +416,11 @@ package body Exp_Util is
          if Validity_Checks_On
            and then
              (Validity_Check_Tests or else Is_Hardbool_Type (T))
+
+           --  no check needed here if validity has already been checked
+           and then not
+             (Validity_Check_Operands and then
+               (Nkind (N) in N_Op or else Nkind (Parent (N)) in N_Op))
          then
             Ensure_Valid (N);
          end if;