From: Pierre-Marie de Rodat <derodat@adacore.com>
To: gcc-patches@gcc.gnu.org
Cc: Piotr Trojanek <trojanek@adacore.com>
Subject: [Ada] Detect infinite loops with operators in exit conditions
Date: Wed, 11 May 2022 08:54:39 +0000 [thread overview]
Message-ID: <20220511085439.GA2167330@adacore.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 824 bytes --]
To warn about infinite loops we detect variables referenced in loop exit
conditions. We handle references within boolean operators, i.e.
comparison and negation, which are likely to appear at the top level of
the condition (e.g. "X > 0"). However, we can easily handle all
operators, because they are likely to appear inside the condition (e.g.
"abs (X) > 0.0").
Cleanup related to a new restriction No_Uninitialized_Local_Scalars.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_warn.adb (Find_Var): Detect all operators; replace
"condition" to "expression" in comments, because when this
routine is called recursively it no longer examines the
condition.
(Is_Suspicious_Function_Name): Reduce scope of a local variable
to avoid shadowing with a parameter of a nested
Substring_Present function.
[-- Attachment #2: patch.diff --]
[-- Type: text/x-diff, Size: 1824 bytes --]
diff --git a/gcc/ada/sem_warn.adb b/gcc/ada/sem_warn.adb
--- a/gcc/ada/sem_warn.adb
+++ b/gcc/ada/sem_warn.adb
@@ -284,15 +284,15 @@ package body Sem_Warn is
procedure Find_Var (N : Node_Id) is
begin
- -- Condition is a direct variable reference
+ -- Expression is a direct variable reference
if Is_Entity_Name (N) then
Ref := N;
Var := Entity (Ref);
- -- Case of condition is a comparison with compile time known value
+ -- If expression is an operator, check its operands
- elsif Nkind (N) in N_Op_Compare then
+ elsif Nkind (N) in N_Binary_Op then
if Compile_Time_Known_Value (Right_Opnd (N)) then
Find_Var (Left_Opnd (N));
@@ -305,9 +305,9 @@ package body Sem_Warn is
return;
end if;
- -- If condition is a negation, check its operand
+ -- If expression is a unary operator, check its operand
- elsif Nkind (N) = N_Op_Not then
+ elsif Nkind (N) in N_Unary_Op then
Find_Var (Right_Opnd (N));
-- Case of condition is function call
@@ -445,8 +445,6 @@ package body Sem_Warn is
---------------------------------
function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
- S : Entity_Id;
-
function Substring_Present (S : String) return Boolean;
-- Returns True if name buffer has given string delimited by non-
-- alphabetic characters or by end of string. S is lower case.
@@ -473,6 +471,10 @@ package body Sem_Warn is
return False;
end Substring_Present;
+ -- Local variables
+
+ S : Entity_Id;
+
-- Start of processing for Is_Suspicious_Function_Name
begin
reply other threads:[~2022-05-11 8:54 UTC|newest]
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