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* [gcc r12-1478] [Ada] Avoid unhelpful dead code warnings
@ 2021-06-15 10:23 Pierre-Marie de Rodat
0 siblings, 0 replies; only message in thread
From: Pierre-Marie de Rodat @ 2021-06-15 10:23 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:ba998f6407ba006a8f8055171ee8e8510f0bc46b
commit r12-1478-gba998f6407ba006a8f8055171ee8e8510f0bc46b
Author: Steve Baird <baird@adacore.com>
Date: Fri Feb 12 16:34:04 2021 -0800
[Ada] Avoid unhelpful dead code warnings
gcc/ada/
* exp_util.adb (Kill_Dead_Code): Generalize the existing
handling of if statements to handle case statements similarly.
Diff:
---
gcc/ada/exp_util.adb | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
index 78797f64165..860525d12a1 100644
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -9238,28 +9238,33 @@ package body Exp_Util is
if W then
-- We suppress the warning if this code is under control of an
- -- if statement, whose condition is a simple identifier, and
- -- either we are in an instance, or warnings off is set for this
- -- identifier. The reason for killing it in the instance case is
- -- that it is common and reasonable for code to be deleted in
- -- instances for various reasons.
+ -- if/case statement and either
+ -- a) we are in an instance and the condition/selector
+ -- has a statically known value; or
+ -- b) the condition/selector is a simple identifier and
+ -- warnings off is set for this identifier.
+ -- Dead code is common and reasonable in instances, so we don't
+ -- want a warning in that case.
- -- Could we use Is_Statically_Unevaluated here???
+ declare
+ C : Node_Id := Empty;
+ begin
+ if Nkind (Parent (N)) = N_If_Statement then
+ C := Condition (Parent (N));
+ elsif Nkind (Parent (N)) = N_Case_Statement_Alternative then
+ C := Expression (Parent (Parent (N)));
+ end if;
- if Nkind (Parent (N)) = N_If_Statement then
- declare
- C : constant Node_Id := Condition (Parent (N));
- begin
- if Nkind (C) = N_Identifier
- and then
- (In_Instance
- or else (Present (Entity (C))
- and then Has_Warnings_Off (Entity (C))))
+ if Present (C) then
+ if (In_Instance and Compile_Time_Known_Value (C))
+ or else (Nkind (C) = N_Identifier
+ and then Present (Entity (C))
+ and then Has_Warnings_Off (Entity (C)))
then
W := False;
end if;
- end;
- end if;
+ end if;
+ end;
-- Generate warning if not suppressed
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