Re: [PATCH] Avoid -fcompare-debug differences caused by the inliner (PR tree-optimization/42645)

[Richard Guenther <rguenther at suse dot de>]

On Mon, 11 Jan 2010, Jakub Jelinek wrote:

> Hi!
> 
> On the testcases below which lack return stmt -fcompare-debug fails, because
> remap_ssa_name called indirectly from copy_debug_stmt creates a SSA_NAME
> which obviously for -g0 isn't created, and differences in SSA_NAME versions
> are known to cause code differences.  On these testcases remap_decl fails
> (returns just the passed in decl and sets processing_debug_stmt = -1,
> so the created SSA_NAME is completely useless, as the debug stmt is
> immediately reset, but even if remap_decl didn't fail, we don't want to
> create it.
> 
> Bootstrapped/regtested on x86_64-linux, additionally tested with assert
> on cc1files/{MICO,FF3D,TRAMP3D} to make sure this sort of thing doesn't
> happen very often on real-world code (it didn't hit at all, except for
> the 2 testcases from this PR).
> 
> Ok for trunk?

Ok.

Thanks,
Richard.

> 2010-01-11  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/42645
> 	* tree-inline.c (processing_debug_stmt): Move earlier.
> 	(remap_ssa_name): If processing_debug_stmt and name wasn't found in
> 	decl_map, set processing_debug_stmt to -1 and return name without
> 	any remapping.
> 
> 	* g++.dg/other/pr42645-1.C: New test.
> 	* g++.dg/other/pr42645-2.C: New test.
> 
> --- gcc/tree-inline.c.jj	2010-01-08 20:48:10.000000000 +0100
> +++ gcc/tree-inline.c	2010-01-11 12:56:46.000000000 +0100
> @@ -171,6 +171,12 @@ insert_debug_decl_map (copy_body_data *i
>    *pointer_map_insert (id->debug_map, key) = value;
>  }
>  
> +/* If nonzero, we're remapping the contents of inlined debug
> +   statements.  If negative, an error has occurred, such as a
> +   reference to a variable that isn't available in the inlined
> +   context.  */
> +int processing_debug_stmt = 0;
> +
>  /* Construct new SSA name for old NAME. ID is the inline context.  */
>  
>  static tree
> @@ -185,6 +191,12 @@ remap_ssa_name (tree name, copy_body_dat
>    if (n)
>      return unshare_expr (*n);
>  
> +  if (processing_debug_stmt)
> +    {
> +      processing_debug_stmt = -1;
> +      return name;
> +    }
> +
>    /* Do not set DEF_STMT yet as statement is not copied yet. We do that
>       in copy_bb.  */
>    new_tree = remap_decl (SSA_NAME_VAR (name), id);
> @@ -244,12 +256,6 @@ remap_ssa_name (tree name, copy_body_dat
>    return new_tree;
>  }
>  
> -/* If nonzero, we're remapping the contents of inlined debug
> -   statements.  If negative, an error has occurred, such as a
> -   reference to a variable that isn't available in the inlined
> -   context.  */
> -int processing_debug_stmt = 0;
> -
>  /* Remap DECL during the copying of the BLOCK tree for the function.  */
>  
>  tree
> --- gcc/testsuite/g++.dg/other/pr42645-1.C.jj	2010-01-11 12:59:50.000000000 +0100
> +++ gcc/testsuite/g++.dg/other/pr42645-1.C	2010-01-11 13:00:40.000000000 +0100
> @@ -0,0 +1,26 @@
> +// PR tree-optimization/42645
> +// { dg-do compile }
> +// { dg-options "-fcompare-debug -O1" }
> +
> +extern void foo ();
> +
> +struct S
> +{
> +  struct T
> +  {
> +    int t1;
> +    char t2[4];
> +    T *t3;
> +  } t;
> +  int m1 () const { return t.t3[0].t1; }
> +  char *m2 () { foo (); }
> +  void m3 (int x) { char *m = m2 (); if (m1 () > 0 && x > 0); }
> +  void m4 () { if (m1 () > 0) for (int i = 0; i < 4; i++) t.t2[i] = 0; }
> +};
> +
> +void
> +f (S *a)
> +{
> +  a->m3 (0);
> +  a->m4 ();
> +}
> --- gcc/testsuite/g++.dg/other/pr42645-2.C.jj	2010-01-11 12:59:53.000000000 +0100
> +++ gcc/testsuite/g++.dg/other/pr42645-2.C	2010-01-11 13:00:55.000000000 +0100
> @@ -0,0 +1,34 @@
> +// PR tree-optimization/42645
> +// { dg-do compile }
> +// { dg-options "-fcompare-debug -O1" }
> +
> +struct C
> +{
> +  bool b;
> +  C ();
> +};
> +
> +static inline C *foo () {}
> +
> +extern void f4 ();
> +
> +static inline int
> +f3 ()
> +{
> +  f4 ();
> +}
> +
> +static inline void
> +f2 (bool b)
> +{
> +  int tmp = f3 ();
> +  if (C ().b && b)
> +    C ();
> +}
> +
> +void
> +f1 ()
> +{
> +  C *c = foo ();
> +  f2 (c->b);
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
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