[PATCH] Fix PR33692, gimplifier strips qualifiers from COMPONENT_REFs

[PATCH] Fix PR33692, gimplifier strips qualifiers from COMPONENT_REFs

[Richard Guenther]

The problem in this PR (ICE with type-checking enabled) is that the
gimplifier in canonicalize_component_ref effectively strips qualifiers
from the referenced structure type in canonicalizing the component type.

Now, I'd argue this function is completely unnecessary, but the safer
bet for stage3 is possibly to correctly canonicalize including the
relevant qualifiers like the following.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Comments?

Thanks,
Richard.

2007-10-08  Richard Guenther  <rguenther@suse.de>

	PR middle-end/33692
	* gimplify.c (canonicalize_component_ref): Honor qualifiers
	of referenced structure and component.

	* gcc.dg/pr33692.c: New testcase.

Index: gimplify.c
===================================================================
*** gimplify.c	(revision 129162)
--- gimplify.c	(working copy)
*************** canonicalize_component_ref (tree *expr_p
*** 1555,1571 ****
    else
      type = TREE_TYPE (TREE_OPERAND (expr, 1));
  
    if (TREE_TYPE (expr) != type)
      {
        tree old_type = TREE_TYPE (expr);
  
        /* Set the type of the COMPONENT_REF to the underlying type.  */
        TREE_TYPE (expr) = type;
  
!       /* And wrap the whole thing inside a NOP_EXPR.  */
!       expr = build1 (NOP_EXPR, old_type, expr);
! 
!       *expr_p = expr;
      }
  }
  
--- 1555,1585 ----
    else
      type = TREE_TYPE (TREE_OPERAND (expr, 1));
  
+   /* One could argue that all the stuff below is not necessary for
+      the non-bitfield case and declare it a FE error if type
+      adjustment would be needed.  */
    if (TREE_TYPE (expr) != type)
      {
+ #ifdef ENABLE_TYPES_CHECKING
        tree old_type = TREE_TYPE (expr);
+ #endif
+       int type_quals;
+ 
+       /* We need to preserve qualifiers and propagate them from
+ 	 operand 0.  */
+       type_quals = TYPE_QUALS (type)
+ 	| TYPE_QUALS (TREE_TYPE (TREE_OPERAND (expr, 0)));
+       if (TYPE_QUALS (type) != type_quals)
+ 	type = build_qualified_type (TYPE_MAIN_VARIANT (type), type_quals);
  
        /* Set the type of the COMPONENT_REF to the underlying type.  */
        TREE_TYPE (expr) = type;
  
! #ifdef ENABLE_TYPES_CHECKING
!       /* It is now a FE error, if the conversion from the canonical
! 	 type to the original expression type is not useless.  */
!       gcc_assert (useless_type_conversion_p (old_type, type));
! #endif
      }
  }
  
Index: testsuite/gcc.dg/pr33692.c
===================================================================
*** testsuite/gcc.dg/pr33692.c	(revision 0)
--- testsuite/gcc.dg/pr33692.c	(revision 0)
***************
*** 0 ****
--- 1,12 ----
+ /* { dg-do compile } */
+ 
+ /* We ICEd with type-checking enabled.  */
+ 
+ typedef struct { int i; } snd_pcm_info_t;
+ typedef struct { snd_pcm_info_t info; } snd_pcm_shm_ctrl_t;
+ void snd_pcm_info(snd_pcm_info_t *);
+ int pcm_shm_cmd(volatile snd_pcm_shm_ctrl_t *ctrl)
+ {
+   snd_pcm_info((snd_pcm_info_t *) &ctrl->info);
+ }
+ 

Re: [PATCH] Fix PR33692, gimplifier strips qualifiers from COMPONENT_REFs

[Ian Lance Taylor]

Richard Guenther <rguenther@suse.de> writes:

> 2007-10-08  Richard Guenther  <rguenther@suse.de>
> 
> 	PR middle-end/33692
> 	* gimplify.c (canonicalize_component_ref): Honor qualifiers
> 	of referenced structure and component.
> 
> 	* gcc.dg/pr33692.c: New testcase.

Looks right to me for stage 3.

Ian