[Ada] Fix latent bug in the analysis of iteration bounds
Arnaud Charlet
charlet@adacore.com
Tue Aug 2 10:17:00 GMT 2011
When the evaluation of the expressions that provide the bounds of a
for-loop statement uses the secondary stack the frontend must generate
code to release it. Although such code was already in the frontend,
its generation was disabled because of a latent bug.
This can be verified using the following test:
procedure Do_Test is
function F (N: Natural) return String is
S : String (1 .. N);
begin
return S;
end;
begin
for J in 1 .. F(300)'Last loop
null;
end loop;
end;
After this patch the expanded code is as follows:
with system.system__secondary_stack;
procedure do_test is
function do_test__f (n : natural) return string is
subtype do_test__f__TsS is string (1 .. n);
null;
s : string (1 .. n);
begin
return s;
end do_test__f;
L_1 : label
begin
S2b : integer;
L_1__B3b : declare
M4b : system__secondary_stack__mark_id :=
$system__secondary_stack__ss_mark;
procedure do_test__L_1__B3b___clean is
begin
$system__secondary_stack__ss_release (M4b);
return;
end do_test__L_1__B3b___clean;
begin
S2b := do_test__f (300)'last;
at end
do_test__L_1__B3b___clean;
end L_1__B3b;
L_1 : for j in 1 .. S2b loop
null;
end loop L_1;
return;
end do_test;
Tested on x86_64-pc-linux-gnu, committed on trunk
2011-08-02 Javier Miranda <miranda@adacore.com>
* sem_ch5.adb (Analyze_Iteration_Scheme.Uses_Secondary_Stack): New
function. Used to be more precise when we generate a variable plus one
assignment to remove side effects in the evaluation of the Bound
expressions.
(Analyze_Iteration_Scheme): Clean attribute analyzed in all the nodes
of the bound expression to force its re-analysis and thus expand the
associated transient scope (if required). Code cleanup replacing the
previous code that declared the constant entity by an invocation to
routine Force_Evaluation which centralizes this work in the frontend.
-------------- next part --------------
Index: sem_ch5.adb
===================================================================
--- sem_ch5.adb (revision 177102)
+++ sem_ch5.adb (working copy)
@@ -95,9 +95,9 @@
procedure Set_Assignment_Type
(Opnd : Node_Id;
Opnd_Type : in out Entity_Id);
- -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type
- -- is the nominal subtype. This procedure is used to deal with cases
- -- where the nominal subtype must be replaced by the actual subtype.
+ -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
+ -- nominal subtype. This procedure is used to deal with cases where the
+ -- nominal subtype must be replaced by the actual subtype.
-------------------------------
-- Diagnose_Non_Variable_Lhs --
@@ -105,8 +105,8 @@
procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
begin
- -- Not worth posting another error if left hand side already
- -- flagged as being illegal in some respect.
+ -- Not worth posting another error if left hand side already flagged
+ -- as being illegal in some respect.
if Error_Posted (N) then
return;
@@ -130,8 +130,8 @@
elsif (Is_Prival (Ent)
and then
(Ekind (Current_Scope) = E_Function
- or else Ekind (Enclosing_Dynamic_Scope (
- Current_Scope)) = E_Function))
+ or else Ekind (Enclosing_Dynamic_Scope
+ (Current_Scope)) = E_Function))
or else
(Ekind (Ent) = E_Component
and then Is_Protected_Type (Scope (Ent)))
@@ -202,10 +202,10 @@
Require_Entity (Opnd);
-- If the assignment operand is an in-out or out parameter, then we
- -- get the actual subtype (needed for the unconstrained case).
- -- If the operand is the actual in an entry declaration, then within
- -- the accept statement it is replaced with a local renaming, which
- -- may also have an actual subtype.
+ -- get the actual subtype (needed for the unconstrained case). If the
+ -- operand is the actual in an entry declaration, then within the
+ -- accept statement it is replaced with a local renaming, which may
+ -- also have an actual subtype.
if Is_Entity_Name (Opnd)
and then (Ekind (Entity (Opnd)) = E_Out_Parameter
@@ -344,8 +344,8 @@
end if;
end if;
- -- The resulting assignment type is T1, so now we will resolve the
- -- left hand side of the assignment using this determined type.
+ -- The resulting assignment type is T1, so now we will resolve the left
+ -- hand side of the assignment using this determined type.
Resolve (Lhs, T1);
@@ -353,8 +353,8 @@
if not Is_Variable (Lhs) then
- -- Ada 2005 (AI-327): Check assignment to the attribute Priority of
- -- a protected object.
+ -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
+ -- protected object.
declare
Ent : Entity_Id;
@@ -452,9 +452,9 @@
("target of assignment operation must not be abstract", Lhs);
end if;
- -- Resolution may have updated the subtype, in case the left-hand
- -- side is a private protected component. Use the correct subtype
- -- to avoid scoping issues in the back-end.
+ -- Resolution may have updated the subtype, in case the left-hand side
+ -- is a private protected component. Use the correct subtype to avoid
+ -- scoping issues in the back-end.
T1 := Etype (Lhs);
@@ -631,7 +631,7 @@
Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
-- For array types, verify that lengths match. If the right hand side
- -- if a function call that has been inlined, the assignment has been
+ -- is a function call that has been inlined, the assignment has been
-- rewritten as a block, and the constraint check will be applied to the
-- assignment within the block.
@@ -648,8 +648,8 @@
-- side is a type conversion to an unconstrained type, a length check
-- is performed on the expression itself during expansion. In rare
-- cases, the redundant length check is computed on an index type
- -- with a different representation, triggering incorrect code in
- -- the back end.
+ -- with a different representation, triggering incorrect code in the
+ -- back end.
Apply_Length_Check (Rhs, Etype (Lhs));
@@ -679,11 +679,11 @@
and then Same_Object (Lhs, Original_Node (Rhs))
- -- But exclude the case where the right side was an operation
- -- that got rewritten (e.g. JUNK + K, where K was known to be
- -- zero). We don't want to warn in such a case, since it is
- -- reasonable to write such expressions especially when K is
- -- defined symbolically in some other package.
+ -- But exclude the case where the right side was an operation that
+ -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
+ -- don't want to warn in such a case, since it is reasonable to write
+ -- such expressions especially when K is defined symbolically in some
+ -- other package.
and then Nkind (Original_Node (Rhs)) not in N_Op
then
@@ -722,11 +722,11 @@
Set_Referenced_Modified (Lhs, Out_Param => False);
end if;
- -- Final step. If left side is an entity, then we may be able to
- -- reset the current tracked values to new safe values. We only have
- -- something to do if the left side is an entity name, and expansion
- -- has not modified the node into something other than an assignment,
- -- and of course we only capture values if it is safe to do so.
+ -- Final step. If left side is an entity, then we may be able to reset
+ -- the current tracked values to new safe values. We only have something
+ -- to do if the left side is an entity name, and expansion has not
+ -- modified the node into something other than an assignment, and of
+ -- course we only capture values if it is safe to do so.
if Is_Entity_Name (Lhs)
and then Nkind (N) = N_Assignment_Statement
@@ -739,8 +739,8 @@
-- If simple variable on left side, warn if this assignment
-- blots out another one (rendering it useless) and note
- -- location of assignment in case no one references value.
- -- We only do this for source assignments, otherwise we can
+ -- location of assignment in case no one references value. We
+ -- only do this for source assignments, otherwise we can
-- generate bogus warnings when an assignment is rewritten as
-- another assignment, and gets tied up with itself.
@@ -809,9 +809,8 @@
begin
Check_Formal_Restriction ("block statement is not allowed", N);
- -- If no handled statement sequence is present, things are really
- -- messed up, and we just return immediately (this is a defence
- -- against previous errors).
+ -- If no handled statement sequence is present, things are really messed
+ -- up, and we just return immediately (defence against previous errors).
if No (HSS) then
return;
@@ -843,10 +842,9 @@
Analyze (Id);
Ent := Entity (Id);
- -- An error defense. If we have an identifier, but no entity,
- -- then something is wrong. If we have previous errors, then
- -- just remove the identifier and continue, otherwise raise
- -- an exception.
+ -- An error defense. If we have an identifier, but no entity, then
+ -- something is wrong. If previous errors, then just remove the
+ -- identifier and continue, otherwise raise an exception.
if No (Ent) then
if Total_Errors_Detected /= 0 then
@@ -887,9 +885,9 @@
Analyze (HSS);
Process_End_Label (HSS, 'e', Ent);
- -- If exception handlers are present, then we indicate that
- -- enclosing scopes contain a block with handlers. We only
- -- need to mark non-generic scopes.
+ -- If exception handlers are present, then we indicate that enclosing
+ -- scopes contain a block with handlers. We only need to mark non-
+ -- generic scopes.
if Present (EH) then
S := Scope (Ent);
@@ -932,17 +930,17 @@
-- Don't care about assigned values
Statements_Analyzed : Boolean := False;
- -- Set True if at least some statement sequences get analyzed.
- -- If False on exit, means we had a serious error that prevented
- -- full analysis of the case statement, and as a result it is not
- -- a good idea to output warning messages about unreachable code.
+ -- Set True if at least some statement sequences get analyzed. If False
+ -- on exit, means we had a serious error that prevented full analysis of
+ -- the case statement, and as a result it is not a good idea to output
+ -- warning messages about unreachable code.
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
procedure Non_Static_Choice_Error (Choice : Node_Id);
- -- Error routine invoked by the generic instantiation below when
- -- the case statement has a non static choice.
+ -- Error routine invoked by the generic instantiation below when the
+ -- case statement has a non static choice.
procedure Process_Statements (Alternative : Node_Id);
-- Analyzes all the statements associated with a case alternative.
@@ -981,16 +979,16 @@
Statements_Analyzed := True;
-- An interesting optimization. If the case statement expression
- -- is a simple entity, then we can set the current value within
- -- an alternative if the alternative has one possible value.
+ -- is a simple entity, then we can set the current value within an
+ -- alternative if the alternative has one possible value.
-- case N is
-- when 1 => alpha
-- when 2 | 3 => beta
-- when others => gamma
- -- Here we know that N is initially 1 within alpha, but for beta
- -- and gamma, we do not know anything more about the initial value.
+ -- Here we know that N is initially 1 within alpha, but for beta and
+ -- gamma, we do not know anything more about the initial value.
if Is_Entity_Name (Exp) then
Ent := Entity (Exp);
@@ -1080,10 +1078,10 @@
return;
end if;
- -- If the case expression is a formal object of mode in out, then
- -- treat it as having a nonstatic subtype by forcing use of the base
- -- type (which has to get passed to Check_Case_Choices below). Also
- -- use base type when the case expression is parenthesized.
+ -- If the case expression is a formal object of mode in out, then treat
+ -- it as having a nonstatic subtype by forcing use of the base type
+ -- (which has to get passed to Check_Case_Choices below). Also use base
+ -- type when the case expression is parenthesized.
if Paren_Count (Exp) > 0
or else (Is_Entity_Name (Exp)
@@ -1148,13 +1146,16 @@
----------------------------
-- If the exit includes a name, it must be the name of a currently open
- -- loop. Otherwise there must be an innermost open loop on the stack,
- -- to which the statement implicitly refers.
+ -- loop. Otherwise there must be an innermost open loop on the stack, to
+ -- which the statement implicitly refers.
-- Additionally, in formal mode:
- -- * the exit can only name the closest enclosing loop;
- -- * an exit with a when clause must be directly contained in a loop;
- -- * an exit without a when clause must be directly contained in an
+
+ -- The exit can only name the closest enclosing loop;
+
+ -- An exit with a when clause must be directly contained in a loop;
+
+ -- An exit without a when clause must be directly contained in an
-- if-statement with no elsif or else, which is itself directly contained
-- in a loop. The exit must be the last statement in the if-statement.
@@ -1177,6 +1178,7 @@
if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
Error_Msg_N ("invalid loop name in exit statement", N);
return;
+
else
if Has_Loop_In_Inner_Open_Scopes (U_Name) then
Check_Formal_Restriction
@@ -1185,6 +1187,7 @@
Set_Has_Exit (U_Name);
end if;
+
else
U_Name := Empty;
end if;
@@ -1194,7 +1197,8 @@
Kind := Ekind (Scope_Id);
if Kind = E_Loop
- and then (No (Target) or else Scope_Id = U_Name) then
+ and then (No (Target) or else Scope_Id = U_Name)
+ then
Set_Has_Exit (Scope_Id);
exit;
@@ -1339,15 +1343,14 @@
-- A special complication arises in the analysis of if statements
- -- The expander has circuitry to completely delete code that it
- -- can tell will not be executed (as a result of compile time known
- -- conditions). In the analyzer, we ensure that code that will be
- -- deleted in this manner is analyzed but not expanded. This is
- -- obviously more efficient, but more significantly, difficulties
- -- arise if code is expanded and then eliminated (e.g. exception
- -- table entries disappear). Similarly, itypes generated in deleted
- -- code must be frozen from start, because the nodes on which they
- -- depend will not be available at the freeze point.
+ -- The expander has circuitry to completely delete code that it can tell
+ -- will not be executed (as a result of compile time known conditions). In
+ -- the analyzer, we ensure that code that will be deleted in this manner is
+ -- analyzed but not expanded. This is obviously more efficient, but more
+ -- significantly, difficulties arise if code is expanded and then
+ -- eliminated (e.g. exception table entries disappear). Similarly, itypes
+ -- generated in deleted code must be frozen from start, because the nodes
+ -- on which they depend will not be available at the freeze point.
procedure Analyze_If_Statement (N : Node_Id) is
E : Node_Id;
@@ -1358,13 +1361,13 @@
Save_In_Deleted_Code : Boolean;
Del : Boolean := False;
- -- This flag gets set True if a True condition has been found,
- -- which means that remaining ELSE/ELSIF parts are deleted.
+ -- This flag gets set True if a True condition has been found, which
+ -- means that remaining ELSE/ELSIF parts are deleted.
procedure Analyze_Cond_Then (Cnode : Node_Id);
- -- This is applied to either the N_If_Statement node itself or
- -- to an N_Elsif_Part node. It deals with analyzing the condition
- -- and the THEN statements associated with it.
+ -- This is applied to either the N_If_Statement node itself or to an
+ -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
+ -- statements associated with it.
-----------------------
-- Analyze_Cond_Then --
@@ -1390,8 +1393,8 @@
elsif Compile_Time_Known_Value (Cond) then
Save_In_Deleted_Code := In_Deleted_Code;
- -- If condition is True, then analyze the THEN statements
- -- and set no expansion for ELSE and ELSIF parts.
+ -- If condition is True, then analyze the THEN statements and set
+ -- no expansion for ELSE and ELSIF parts.
if Is_True (Expr_Value (Cond)) then
Analyze_Statements (Tstm);
@@ -1419,9 +1422,9 @@
-- Start of Analyze_If_Statement
begin
- -- Initialize exit count for else statements. If there is no else
- -- part, this count will stay non-zero reflecting the fact that the
- -- uncovered else case is an unblocked exit.
+ -- Initialize exit count for else statements. If there is no else part,
+ -- this count will stay non-zero reflecting the fact that the uncovered
+ -- else case is an unblocked exit.
Unblocked_Exit_Count := 1;
Analyze_Cond_Then (N);
@@ -1481,9 +1484,8 @@
-- Analyze_Implicit_Label_Declaration --
----------------------------------------
- -- An implicit label declaration is generated in the innermost
- -- enclosing declarative part. This is done for labels as well as
- -- block and loop names.
+ -- An implicit label declaration is generated in the innermost enclosing
+ -- declarative part. This is done for labels, and block and loop names.
-- Note: any changes in this routine may need to be reflected in
-- Analyze_Label_Entity.
@@ -1517,6 +1519,12 @@
-- to capture the bounds, so that the function result can be finalized
-- in timely fashion.
+ function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean;
+ -- N is the node for an arbitrary construct. This function searches the
+ -- construct N to see if any expressions within it contain function
+ -- calls that use the secondary stack, returning True if any such call
+ -- is found, and False otherwise.
+
--------------------
-- Process_Bounds --
--------------------
@@ -1571,8 +1579,6 @@
Analyze_And_Resolve (Original_Bound, Typ);
- Id := Make_Temporary (Loc, 'S', Original_Bound);
-
-- Normally, the best approach is simply to generate a constant
-- declaration that captures the bound. However, there is a nasty
-- case where this is wrong. If the bound is complex, and has a
@@ -1584,33 +1590,13 @@
-- proper trace of the value, useful in optimizations that get rid
-- of junk range checks.
- -- Probably we want something like the Side_Effect_Free routine
- -- in Exp_Util, but for now, we just optimize the cases of 'Last
- -- and 'First applied to an entity, since these are the important
- -- cases for range check optimizations.
+ if not Has_Call_Using_Secondary_Stack (N) then
+ Force_Evaluation (Original_Bound);
+ return Original_Bound;
+ end if;
- if Nkind (Original_Bound) = N_Attribute_Reference
- and then (Attribute_Name (Original_Bound) = Name_First
- or else
- Attribute_Name (Original_Bound) = Name_Last)
- and then Is_Entity_Name (Prefix (Original_Bound))
- then
- Decl :=
- Make_Object_Declaration (Loc,
- Defining_Identifier => Id,
- Constant_Present => True,
- Object_Definition => New_Occurrence_Of (Typ, Loc),
- Expression => Relocate_Node (Original_Bound));
+ Id := Make_Temporary (Loc, 'R', Original_Bound);
- -- Insert declaration at proper place. If loop comes from an
- -- enclosing quantified expression, the insertion point is
- -- arbitrarily far up in the tree.
-
- Insert_Action (Parent (N), Decl);
- Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
- return Expression (Decl);
- end if;
-
-- Here we make a declaration with a separate assignment
-- statement, and insert before loop header.
@@ -1624,6 +1610,14 @@
Name => New_Occurrence_Of (Id, Loc),
Expression => Relocate_Node (Original_Bound));
+ -- We must recursively clean in the relocated expression the flag
+ -- analyzed to ensure that the expression is reanalyzed. Required
+ -- to ensure that the transient scope is established now (because
+ -- Establish_Transient_Scope discarded generating transient scopes
+ -- in the analysis of the iteration scheme).
+
+ Reset_Analyzed_Flags (Expression (Assign));
+
Insert_Actions (Parent (N), New_List (Decl, Assign));
Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
@@ -1638,11 +1632,11 @@
-- Start of processing for Process_Bounds
begin
- -- Determine expected type of range by analyzing separate copy
- -- Do the analysis and resolution of the copy of the bounds with
- -- expansion disabled, to prevent the generation of finalization
- -- actions on each bound. This prevents memory leaks when the
- -- bounds contain calls to functions returning controlled arrays.
+ -- Determine expected type of range by analyzing separate copy Do the
+ -- analysis and resolution of the copy of the bounds with expansion
+ -- disabled, to prevent the generation of finalization actions on
+ -- each bound. This prevents memory leaks when the bounds contain
+ -- calls to functions returning controlled arrays.
Set_Parent (R_Copy, Parent (R));
Save_Analysis := Full_Analysis;
@@ -1699,11 +1693,10 @@
Typ := Etype (R_Copy);
- -- If the type of the discrete range is Universal_Integer, then
- -- the bound's type must be resolved to Integer, and any object
- -- used to hold the bound must also have type Integer, unless the
- -- literal bounds are constant-folded expressions that carry a user-
- -- defined type.
+ -- If the type of the discrete range is Universal_Integer, then the
+ -- bound's type must be resolved to Integer, and any object used to
+ -- hold the bound must also have type Integer, unless the literal
+ -- bounds are constant-folded expressions with a user-defined type.
if Typ = Universal_Integer then
if Nkind (Lo) = N_Integer_Literal
@@ -1789,12 +1782,70 @@
end if;
end Check_Controlled_Array_Attribute;
+ ------------------------------------
+ -- Has_Call_Using_Secondary_Stack --
+ ------------------------------------
+
+ function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean is
+
+ function Check_Call (N : Node_Id) return Traverse_Result;
+ -- Check if N is a function call which uses the secondary stack
+
+ ----------------
+ -- Check_Call --
+ ----------------
+
+ function Check_Call (N : Node_Id) return Traverse_Result is
+ Nam : Node_Id;
+ Subp : Entity_Id;
+ Return_Typ : Entity_Id;
+
+ begin
+ if Nkind (N) = N_Function_Call then
+ Nam := Name (N);
+
+ -- Call using access to subprogram with explicit dereference
+
+ if Nkind (Nam) = N_Explicit_Dereference then
+ Subp := Etype (Nam);
+
+ -- Normal case
+
+ else
+ Subp := Entity (Nam);
+ end if;
+
+ Return_Typ := Etype (Subp);
+
+ if Is_Composite_Type (Return_Typ)
+ and then not Is_Constrained (Return_Typ)
+ then
+ return Abandon;
+
+ elsif Sec_Stack_Needed_For_Return (Subp) then
+ return Abandon;
+ end if;
+ end if;
+
+ -- Continue traversing the tree
+
+ return OK;
+ end Check_Call;
+
+ function Check_Calls is new Traverse_Func (Check_Call);
+
+ -- Start of processing for Has_Call_Using_Secondary_Stack
+
+ begin
+ return Check_Calls (N) = Abandon;
+ end Has_Call_Using_Secondary_Stack;
+
-- Start of processing for Analyze_Iteration_Scheme
begin
- -- If this is a rewritten quantified expression, the iteration
- -- scheme has been analyzed already. Do no repeat analysis because
- -- the loop variable is already declared.
+ -- If this is a rewritten quantified expression, the iteration scheme
+ -- has been analyzed already. Do no repeat analysis because the loop
+ -- variable is already declared.
if Analyzed (N) then
return;
@@ -1812,8 +1863,8 @@
Cond : constant Node_Id := Condition (N);
begin
- -- For WHILE loop, verify that the condition is a Boolean
- -- expression and resolve and check it.
+ -- For WHILE loop, verify that the condition is a Boolean expression
+ -- and resolve and check it.
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
@@ -1835,8 +1886,8 @@
begin
Enter_Name (Id);
- -- We always consider the loop variable to be referenced,
- -- since the loop may be used just for counting purposes.
+ -- We always consider the loop variable to be referenced, since
+ -- the loop may be used just for counting purposes.
Generate_Reference (Id, N, ' ');
@@ -2000,8 +2051,8 @@
if not Inside_A_Generic
and then not In_Instance
then
- -- Specialize msg if invalid values could make
- -- the loop non-null after all.
+ -- Specialize msg if invalid values could make the
+ -- loop non-null after all.
if Compile_Time_Compare
(L, H, Assume_Valid => False) = GT
@@ -2010,9 +2061,9 @@
("?loop range is null, loop will not execute",
DS);
- -- Since we know the range of the loop is
- -- null, set the appropriate flag to remove
- -- the loop entirely during expansion.
+ -- Since we know the range of the loop is null,
+ -- set the appropriate flag to remove the loop
+ -- entirely during expansion.
Set_Is_Null_Loop (Parent (N));
@@ -2179,8 +2230,8 @@
begin
if Present (Id) then
- -- Make name visible, e.g. for use in exit statements. Loop
- -- labels are always considered to be referenced.
+ -- Make name visible, e.g. for use in exit statements. Loop labels
+ -- are always considered to be referenced.
Analyze (Id);
Ent := Entity (Id);
@@ -2227,10 +2278,10 @@
Set_Parent (Ent, Loop_Statement);
end if;
- -- Kill current values on entry to loop, since statements in body of
- -- loop may have been executed before the loop is entered. Similarly we
- -- kill values after the loop, since we do not know that the body of the
- -- loop was executed.
+ -- Kill current values on entry to loop, since statements in the body of
+ -- the loop may have been executed before the loop is entered. Similarly
+ -- we kill values after the loop, since we do not know that the body of
+ -- the loop was executed.
Kill_Current_Values;
Push_Scope (Ent);
@@ -2251,8 +2302,8 @@
Check_Infinite_Loop_Warning (N);
end if;
- -- Code after loop is unreachable if the loop has no WHILE or FOR
- -- and contains no EXIT statements within the body of the loop.
+ -- Code after loop is unreachable if the loop has no WHILE or FOR and
+ -- contains no EXIT statements within the body of the loop.
if No (Iter) and then not Has_Exit (Ent) then
Check_Unreachable_Code (N);
@@ -2282,9 +2333,9 @@
begin
-- The labels declared in the statement list are reachable from
- -- statements in the list. We do this as a prepass so that any
- -- goto statement will be properly flagged if its target is not
- -- reachable. This is not required, but is nice behavior!
+ -- statements in the list. We do this as a prepass so that any goto
+ -- statement will be properly flagged if its target is not reachable.
+ -- This is not required, but is nice behavior!
S := First (L);
while Present (S) loop
@@ -2331,10 +2382,9 @@
Conditional_Statements_End;
- -- Make labels unreachable. Visibility is not sufficient, because
- -- labels in one if-branch for example are not reachable from the
- -- other branch, even though their declarations are in the enclosing
- -- declarative part.
+ -- Make labels unreachable. Visibility is not sufficient, because labels
+ -- in one if-branch for example are not reachable from the other branch,
+ -- even though their declarations are in the enclosing declarative part.
S := First (L);
while Present (S) loop
@@ -2365,9 +2415,8 @@
Nxt := Original_Node (Next (N));
-- If a label follows us, then we never have dead code, since
- -- someone could branch to the label, so we just ignore it,
- -- unless we are in formal mode where goto statements are not
- -- allowed.
+ -- someone could branch to the label, so we just ignore it, unless
+ -- we are in formal mode where goto statements are not allowed.
if Nkind (Nxt) = N_Label and then not Formal_Verification_Mode then
return;
@@ -2433,10 +2482,10 @@
end if;
end if;
- -- If the unconditional transfer of control instruction is
- -- the last statement of a sequence, then see if our parent
- -- is one of the constructs for which we count unblocked exits,
- -- and if so, adjust the count.
+ -- If the unconditional transfer of control instruction is the
+ -- last statement of a sequence, then see if our parent is one of
+ -- the constructs for which we count unblocked exits, and if so,
+ -- adjust the count.
else
P := Parent (N);
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