From: Thomas Koenig <tkoenig@gcc.gnu.org>
Date: Sun, 14 Jun 2020 11:01:24 +0000 (+0200)
Subject: When avoiding double deallocation, look at namespace, expression and component.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1af22e455584ef5fcad2b4474c1efc3fd26f6cb3;p=gcc.git

When avoiding double deallocation, look at namespace, expression and component.

Our finalization handling is a mess.  Really, we should get to try and get
this fixed for gcc 11.

In the meantime, here is a patch which fixes a regression I introduced
when fixing a regression with a memory leak.  The important thing
here is to realize that we do not need to finalize (and deallocate)
multiple times for the same expression and the same component
in the same namespace.  It might cause code size regressions, but
better big code than wrong code...

gcc/fortran/ChangeLog:

	PR fortran/94109
	* class.c (finalize_component): Return early if finalization has
	already happened for expression and component within namespace.
	* gfortran.h (gfc_was_finalized): New type.
	(gfc_namespace): Add member was_finalzed.
	(gfc_expr): Remove finalized.
	* symbol.c (gfc_free_namespace): Free was_finalized.

gcc/testsuite/ChangeLog:

	PR fortran/94109
	* gfortran.dg/finalize_34.f90: Adjust free counts.
	* gfortran.dg/finalize_36.f90: New test.
---

diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c
index 2b55859ce75..cfc450283fa 100644
--- a/gcc/fortran/class.c
+++ b/gcc/fortran/class.c
@@ -920,12 +920,18 @@ finalize_component (gfc_expr *expr, gfc_symbol *derived, gfc_component *comp,
 {
   gfc_expr *e;
   gfc_ref *ref;
+  gfc_was_finalized *f;
 
   if (!comp_is_finalizable (comp))
     return;
 
-  if (expr->finalized)
-    return;
+  /* If this expression with this component has been finalized
+     already in this namespace, there is nothing to do.  */
+  for (f = sub_ns->was_finalized; f; f = f->next)
+    {
+      if (f->e == expr && f->c == comp)
+	return;
+    }
 
   e = gfc_copy_expr (expr);
   if (!e->ref)
@@ -1055,7 +1061,13 @@ finalize_component (gfc_expr *expr, gfc_symbol *derived, gfc_component *comp,
 			    sub_ns);
       gfc_free_expr (e);
     }
-  expr->finalized = 1;
+
+  /* Record that this was finalized already in this namespace.  */
+  f = sub_ns->was_finalized;
+  sub_ns->was_finalized = XCNEW (gfc_was_finalized);
+  sub_ns->was_finalized->e = expr;
+  sub_ns->was_finalized->c = comp;
+  sub_ns->was_finalized->next = f;
 }
 
 
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 6d76efb5298..c12a8bef277 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1774,6 +1774,16 @@ gfc_oacc_routine_name;
 
 #define gfc_get_oacc_routine_name() XCNEW (gfc_oacc_routine_name)
 
+/* Node in linked list to see what has already been finalized
+   earlier.  */
+
+typedef struct gfc_was_finalized {
+  gfc_expr *e;
+  gfc_component *c;
+  struct gfc_was_finalized *next;
+}
+gfc_was_finalized;
+
 /* A namespace describes the contents of procedure, module, interface block
    or BLOCK construct.  */
 /* ??? Anything else use these?  */
@@ -1866,6 +1876,11 @@ typedef struct gfc_namespace
   /* Linked list of !$omp declare simd constructs.  */
   struct gfc_omp_declare_simd *omp_declare_simd;
 
+  /* A hash set for the the gfc expressions that have already
+     been finalized in this namespace.  */
+
+  gfc_was_finalized *was_finalized;
+
   /* Set to 1 if namespace is a BLOCK DATA program unit.  */
   unsigned is_block_data:1;
 
@@ -2218,9 +2233,6 @@ typedef struct gfc_expr
   /* Set this if the expression came from expanding an array constructor.  */
   unsigned int from_constructor : 1;
 
-  /* Set this if the expression has already been finalized.  */
-  unsigned int finalized : 1;
-
   /* If an expression comes from a Hollerith constant or compile-time
      evaluation of a transfer statement, it may have a prescribed target-
      memory representation, and these cannot always be backformed from
diff --git a/gcc/fortran/symbol.c b/gcc/fortran/symbol.c
index b96706138c9..ba388ff598d 100644
--- a/gcc/fortran/symbol.c
+++ b/gcc/fortran/symbol.c
@@ -4017,6 +4017,7 @@ gfc_free_namespace (gfc_namespace *ns)
 {
   gfc_namespace *p, *q;
   int i;
+  gfc_was_finalized *f;
 
   if (ns == NULL)
     return;
@@ -4049,6 +4050,17 @@ gfc_free_namespace (gfc_namespace *ns)
     gfc_free_interface (ns->op[i]);
 
   gfc_free_data (ns->data);
+
+  /* Free all the expr + component combinations that have been
+     finalized.  */
+  f = ns->was_finalized;
+  while (f)
+    {
+      gfc_was_finalized* current = f;
+      f = f->next;
+      free (current);
+    }
+
   p = ns->contained;
   free (ns);
 
diff --git a/gcc/testsuite/gfortran.dg/finalize_34.f90 b/gcc/testsuite/gfortran.dg/finalize_34.f90
index fef7dac6d89..8fb801d4235 100644
--- a/gcc/testsuite/gfortran.dg/finalize_34.f90
+++ b/gcc/testsuite/gfortran.dg/finalize_34.f90
@@ -22,4 +22,4 @@ program main
   use testmodule
   type(evtlist_type), dimension(10) :: a
 end program main
-! { dg-final  { scan-tree-dump-times "__builtin_free" 12 "original" } }
+! { dg-final  { scan-tree-dump-times "__builtin_free" 24 "original" } }
diff --git a/gcc/testsuite/gfortran.dg/finalize_36.f90 b/gcc/testsuite/gfortran.dg/finalize_36.f90
new file mode 100644
index 00000000000..432f5472aeb
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/finalize_36.f90
@@ -0,0 +1,39 @@
+! { dg-do run }
+! { dg-additional-options "-fdump-tree-original" }
+! PR 94109
+! This used to leak memory.  Test case by Antony Lewis.
+    module debug
+    implicit none
+
+    Type Tester
+        real, dimension(:), allocatable :: Dat, Dat2
+    end Type
+
+    Type TestType2
+        Type(Tester) :: T
+    end type TestType2
+
+    contains
+
+    subroutine Leaker
+    class(TestType2), pointer :: ActiveState
+    Type(Tester) :: Temp
+
+    allocate(Temp%Dat2(10000))
+
+    allocate(TestType2::ActiveState)
+    ActiveState%T = Temp
+    deallocate(ActiveState)
+
+    end subroutine
+
+    end module
+
+
+    program run
+    use debug
+
+    call Leaker()
+
+    end program
+! { dg-final { scan-tree-dump-times "__builtin_free\\ \\(ptr2" 4 "original" } }