Patchwork [PR,libmudflap/53952] don't check access to non-mem decls

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Submitter Alexandre Oliva
Date Dec. 6, 2012, 3:59 a.m.
Message ID <ord2ynn856.fsf@livre.localdomain>
Download mbox | patch
Permalink /patch/204125/
State New
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Comments

Alexandre Oliva - Dec. 6, 2012, 3:59 a.m.
SRA (and perhaps other passes?) introduce “addressable” MEM_REFs to
variables that were not addressable at the time mudflap1 ran registering
valid memory ranges; when mudflap2 ran to emit the checks, it found such
MEM_REFs, marking the variables as addressable and emitting checks that
will fail at run time.

This patch refactors mem_ref_refers_to_non_mem_p so that it retains its
behavior, while introducing a variant for use by tree-mudflap.c that
assumes a variable that doesn't have its RTL set may end up in a
register.

Regstrapped on x86_64-linux-gnu.  Ok to install?
Richard Guenther - Dec. 6, 2012, 9:18 a.m.
On Thu, Dec 6, 2012 at 4:59 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
> SRA (and perhaps other passes?) introduce “addressable” MEM_REFs to
> variables that were not addressable at the time mudflap1 ran registering
> valid memory ranges; when mudflap2 ran to emit the checks, it found such
> MEM_REFs, marking the variables as addressable and emitting checks that
> will fail at run time.
>
> This patch refactors mem_ref_refers_to_non_mem_p so that it retains its
> behavior, while introducing a variant for use by tree-mudflap.c that
> assumes a variable that doesn't have its RTL set may end up in a
> register.
>
> Regstrapped on x86_64-linux-gnu.  Ok to install?

Ok.

Thanks,
Richard.

>
>
> --
> Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
> You must be the change you wish to see in the world. -- Gandhi
> Be Free! -- http://FSFLA.org/   FSF Latin America board member
> Free Software Evangelist      Red Hat Brazil Compiler Engineer
>

Patch

Fix mudflap errors on access to SRAed variables.

From: Alexandre Oliva <aoliva@redhat.com>

for  gcc/ChangeLog

	PR libmudflap/53952
	* expr.c (mem_ref_refers_to_non_mem_p): Factor out
	implementation into...
	(addr_expr_of_non_mem_decl_p_1): ... this new function.
	(addr_expr_of_non_mem_decl_p): New.
	* tree.h (addr_expr_of_non_mem_decl_p): Declare.
	* tree-mudflap.c (mf_xform_derefs_1): Don't change MEM_REFs
	and TARGET_MEM_REFs that have an ADDR_EXPR of a non-mem DECL
	as base operand.
---

 gcc/expr.c         |   45 ++++++++++++++++++++++++++++++++++++---------
 gcc/tree-mudflap.c |    6 ++++++
 gcc/tree.h         |    3 +++
 3 files changed, 45 insertions(+), 9 deletions(-)


diff --git a/gcc/expr.c b/gcc/expr.c
index 48e2581..7e86983 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -4557,21 +4557,48 @@  get_bit_range (unsigned HOST_WIDE_INT *bitstart,
   *bitend = *bitstart + tree_low_cst (DECL_SIZE (repr), 1) - 1;
 }
 
+/* Returns true if ADDR is an ADDR_EXPR of a DECL that does not reside
+   in memory and has non-BLKmode.  DECL_RTL must not be a MEM; if
+   DECL_RTL was not set yet, return NORTL.  */
+
+static inline bool
+addr_expr_of_non_mem_decl_p_1 (tree addr, bool nortl)
+{
+  if (TREE_CODE (addr) != ADDR_EXPR)
+    return false;
+
+  tree base = TREE_OPERAND (addr, 0);
+
+  if (!DECL_P (base)
+      || TREE_ADDRESSABLE (base)
+      || DECL_MODE (base) == BLKmode)
+    return false;
+
+  if (!DECL_RTL_SET_P (base))
+    return nortl;
+
+  return (!MEM_P (DECL_RTL (base)));
+}
+
 /* Returns true if the MEM_REF REF refers to an object that does not
    reside in memory and has non-BLKmode.  */
 
-static bool
+static inline bool
 mem_ref_refers_to_non_mem_p (tree ref)
 {
   tree base = TREE_OPERAND (ref, 0);
-  if (TREE_CODE (base) != ADDR_EXPR)
-    return false;
-  base = TREE_OPERAND (base, 0);
-  return (DECL_P (base)
-	  && !TREE_ADDRESSABLE (base)
-	  && DECL_MODE (base) != BLKmode
-	  && DECL_RTL_SET_P (base)
-	  && !MEM_P (DECL_RTL (base)));
+  return addr_expr_of_non_mem_decl_p_1 (base, false);
+}
+
+/* Return TRUE iff OP is an ADDR_EXPR of a DECL that's not
+   addressable.  This is very much like mem_ref_refers_to_non_mem_p,
+   but instead of the MEM_REF, it takes its base, and it doesn't
+   assume a DECL is in memory just because its RTL is not set yet.  */
+
+bool
+addr_expr_of_non_mem_decl_p (tree op)
+{
+  return addr_expr_of_non_mem_decl_p_1 (op, true);
 }
 
 /* Expand an assignment that stores the value of FROM into TO.  If NONTEMPORAL
diff --git a/gcc/tree-mudflap.c b/gcc/tree-mudflap.c
index 9b9c549..90d0448 100644
--- a/gcc/tree-mudflap.c
+++ b/gcc/tree-mudflap.c
@@ -877,6 +877,9 @@  mf_xform_derefs_1 (gimple_stmt_iterator *iter, tree *tp,
       break;
 
     case MEM_REF:
+      if (addr_expr_of_non_mem_decl_p (TREE_OPERAND (t, 0)))
+	return;
+
       addr = fold_build_pointer_plus_loc (location, TREE_OPERAND (t, 0),
 					  TREE_OPERAND (t, 1));
       base = addr;
@@ -886,6 +889,9 @@  mf_xform_derefs_1 (gimple_stmt_iterator *iter, tree *tp,
       break;
 
     case TARGET_MEM_REF:
+      if (addr_expr_of_non_mem_decl_p (TMR_BASE (t)))
+	return;
+
       addr = tree_mem_ref_addr (ptr_type_node, t);
       base = addr;
       limit = fold_build_pointer_plus_hwi_loc (location,
diff --git a/gcc/tree.h b/gcc/tree.h
index a830e28..9b75d36 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -6313,6 +6313,9 @@  extern unsigned HOST_WIDE_INT compute_builtin_object_size (tree, int);
    succeed.  */
 extern int can_move_by_pieces (unsigned HOST_WIDE_INT, unsigned int);
 
+/* Is it an ADDR_EXPR of a DECL that's not in memory?  */
+extern bool addr_expr_of_non_mem_decl_p (tree);
+
 extern unsigned HOST_WIDE_INT highest_pow2_factor (const_tree);
 extern tree build_personality_function (const char *);