[patch] Fix GIMPLE verification failure on CONSTRUCTOR

[patch] Fix GIMPLE verification failure on CONSTRUCTOR

[Eric Botcazou]

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This is a regression present on mainline and 4.7 branch.  The error message is:

p.adb: In function 'P.Proc':
p.adb:3:4: error: non-trivial conversion at assignment
system__address
void (*<T590>) (void)
r.callback.callback.address = q__proc;

+===========================GNAT BUG DETECTED==============================+
| 4.8.0 20120716 (experimental) [trunk revision 189525] (x86_64-suse-linux) GCC 
error:|
| verify_gimple failed                                                     |
| Error detected around p.adb:3:4 

We lose a cast in an initializer before gimplification, hence type mismatch.
This happens as follows: a CONSTRUCTOR used as the initializer of a global 
constant and whose only value contains the cast is embedded (shared) in a 
CONSTRUCTOR used as the initializer of a second global constant, which is in 
turn embedded (shared) in a CONSTRUCTOR used as the initializer of a local 
variable.

The sharing is fine, since we have an unsharing pass running right before 
gimplification.  The problem is that, since:

r171903 | matz | 2011-04-03 13:13:09 +0200 (Sun, 03 Apr 2011) | 7 lines

        * cgraphbuild.c (record_reference): Canonicalize constructor
        values.
        * gimple-fold.c (canonicalize_constructor_val): Accept being called
        without function context.
        * cgraphunit.c (cgraph_finalize_compilation_unit): Clear
        current_function_decl and cfun.

record_reference can modify the contents of CONSTRUCTORs _before_ the unsharing 
pass is run and yield invalid GENERIC and later invalid GIMPLE.

Tested on x86_64-suse-linux, OK for the mainline and 4.7 branch?


2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>

	* gimple-fold.c (canonicalize_constructor_val): Strip only useless type
	conversions.


2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>

	* gnat.dg/aggr20.ad[sb]: New test.
	* gnat.dg/aggr20_pkg.ads: New helper.


-- 
Eric Botcazou

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Index: gimple-fold.c
===================================================================
--- gimple-fold.c	(revision 189525)
+++ gimple-fold.c	(working copy)
@@ -139,7 +139,7 @@ can_refer_decl_in_current_unit_p (tree d
 tree
 canonicalize_constructor_val (tree cval, tree from_decl)
 {
-  STRIP_NOPS (cval);
+  STRIP_USELESS_TYPE_CONVERSION (cval);
   if (TREE_CODE (cval) == POINTER_PLUS_EXPR
       && TREE_CODE (TREE_OPERAND (cval, 1)) == INTEGER_CST)
     {

[-- Attachment #3: aggr20.adb --]
[-- Type: text/x-adasrc, Size: 147 bytes --]

-- { dg-do compile }

package body Aggr20 is

   procedure Proc (R : out Rec3) is
   begin
      R := (Callback => Nil_Rec2);
   end;

end Aggr20;

[-- Attachment #4: aggr20.ads --]
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with Aggr20_Pkg; use Aggr20_Pkg;
with System;

package Aggr20 is

   type Rec1 is record
      Address : System.Address;
   end record;

   Nil_Rec1 : constant Rec1 := (Address => Default_Nil_Address);

   type Rec2 is record
      Callback : Rec1;
   end record;

   Nil_Rec2 : constant Rec2 := (Callback => Nil_Rec1);

   type Rec3 is record
      Callback : Rec2;
   end record;

   procedure Proc (R : out Rec3);

end Aggr20;

[-- Attachment #5: aggr20_pkg.ads --]
[-- Type: text/x-adasrc, Size: 140 bytes --]

with System;

package Aggr20_Pkg is

   procedure Proc;

   Default_Nil_Address : constant System.Address := Proc'Address;

end Aggr20_Pkg;

Re: [patch] Fix GIMPLE verification failure on CONSTRUCTOR

[Richard Guenther]

On Wed, Jul 18, 2012 at 4:25 PM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> This is a regression present on mainline and 4.7 branch.  The error message is:
>
> p.adb: In function 'P.Proc':
> p.adb:3:4: error: non-trivial conversion at assignment
> system__address
> void (*<T590>) (void)
> r.callback.callback.address = q__proc;
>
> +===========================GNAT BUG DETECTED==============================+
> | 4.8.0 20120716 (experimental) [trunk revision 189525] (x86_64-suse-linux) GCC
> error:|
> | verify_gimple failed                                                     |
> | Error detected around p.adb:3:4
>
> We lose a cast in an initializer before gimplification, hence type mismatch.
> This happens as follows: a CONSTRUCTOR used as the initializer of a global
> constant and whose only value contains the cast is embedded (shared) in a
> CONSTRUCTOR used as the initializer of a second global constant, which is in
> turn embedded (shared) in a CONSTRUCTOR used as the initializer of a local
> variable.
>
> The sharing is fine, since we have an unsharing pass running right before
> gimplification.  The problem is that, since:
>
> r171903 | matz | 2011-04-03 13:13:09 +0200 (Sun, 03 Apr 2011) | 7 lines
>
>         * cgraphbuild.c (record_reference): Canonicalize constructor
>         values.
>         * gimple-fold.c (canonicalize_constructor_val): Accept being called
>         without function context.
>         * cgraphunit.c (cgraph_finalize_compilation_unit): Clear
>         current_function_decl and cfun.
>
> record_reference can modify the contents of CONSTRUCTORs _before_ the unsharing
> pass is run and yield invalid GENERIC and later invalid GIMPLE.
>
> Tested on x86_64-suse-linux, OK for the mainline and 4.7 branch?

Ok.

Thanks,
Richard.

>
> 2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>
>
>         * gimple-fold.c (canonicalize_constructor_val): Strip only useless type
>         conversions.
>
>
> 2012-07-18  Eric Botcazou  <ebotcazou@adacore.com>
>
>         * gnat.dg/aggr20.ad[sb]: New test.
>         * gnat.dg/aggr20_pkg.ads: New helper.
>
>
> --
> Eric Botcazou