[PATCH] PR60092 - lower posix_memalign to make align-info accessible

[Richard Biener]

On Wed, 12 Feb 2014, Andreas Krebbel wrote:

> On 07/02/14 10:33, Richard Biener wrote:
> > + static void
> > + lower_builtin_posix_memalign (gimple_stmt_iterator *gsi)
> > + {
> > +   gimple stmt = gsi_stmt (*gsi);
> > +   tree pptr = gimple_call_arg (stmt, 0);
> > +   tree align = gimple_call_arg (stmt, 1);
> > +   tree ptr = create_tmp_reg (ptr_type_node, NULL);
> > +   if (TREE_CODE (pptr) == ADDR_EXPR)
> > +     {
> > +       tree tem = create_tmp_var (ptr_type_node, NULL);
> > +       TREE_ADDRESSABLE (tem) = 1;
> > +       gimple_call_set_arg (stmt, 0, build_fold_addr_expr (tem));
> > +       stmt = gimple_build_assign (ptr, tem);
> > +     }
> > +   else
> > +     stmt = gimple_build_assign (ptr,
> > + 				fold_build2 (MEM_REF, ptr_type_node, pptr,
> > + 					     build_int_cst (ptr_type_node, 0)));
> > +   gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
> > +   stmt = gimple_build_call (builtin_decl_implicit (BUILT_IN_ASSUME_ALIGNED),
> > + 			    2, ptr, align);
> > +   gimple_call_set_lhs (stmt, ptr);
> > +   gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
> > +   stmt = gimple_build_assign (fold_build2 (MEM_REF, ptr_type_node, pptr,
> > + 					   build_int_cst (ptr_type_node, 0)),
> > + 			      ptr);
> > +   gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
> > + }
> 
> Hi,
> 
> creating a new var for the output parameter throws away the value already in there.  But this value
> must not change when posix_memalign e.g. returns with ENOMEM.  It breaks the glibc posix_memalign
> testcase on s390 (somewhat reduced here):

Bah.  I am testing the following.

Richard.

2014-02-12  Richard Biener  <rguenther@suse.de>

	PR middle-end/60092
	* gimple-low.c (lower_builtin_posix_memalign): Initialize the new
	temporary properly.
	(lower_stmt): Restrict lowering of posix_memalign to when
	-ftree-bit-ccp is enabled.

	* gcc.dg/pr60092.c: New testcase.

Index: gcc/gimple-low.c
===================================================================
*** gcc/gimple-low.c	(revision 207714)
--- gcc/gimple-low.c	(working copy)
*************** lower_stmt (gimple_stmt_iterator *gsi, s
*** 336,342 ****
  		data->cannot_fallthru = false;
  		return;
  	      }
! 	    else if (DECL_FUNCTION_CODE (decl) == BUILT_IN_POSIX_MEMALIGN)
  	      {
  		lower_builtin_posix_memalign (gsi);
  		return;
--- 336,343 ----
  		data->cannot_fallthru = false;
  		return;
  	      }
! 	    else if (DECL_FUNCTION_CODE (decl) == BUILT_IN_POSIX_MEMALIGN
! 		     && flag_tree_bit_ccp)
  	      {
  		lower_builtin_posix_memalign (gsi);
  		return;
*************** lower_builtin_setjmp (gimple_stmt_iterat
*** 786,792 ****
       tem = __builtin_assume_aligned (tem, align);
       *ptr = tem;
     or to
!      void *tem;
       posix_memalign (&tem, align, size);
       ttem = tem;
       ttem = __builtin_assume_aligned (ttem, align);
--- 787,793 ----
       tem = __builtin_assume_aligned (tem, align);
       *ptr = tem;
     or to
!      void *tem = ptr;
       posix_memalign (&tem, align, size);
       ttem = tem;
       ttem = __builtin_assume_aligned (ttem, align);
*************** lower_builtin_posix_memalign (gimple_stm
*** 806,811 ****
--- 807,819 ----
        tree tem = create_tmp_var (ptr_type_node, NULL);
        TREE_ADDRESSABLE (tem) = 1;
        gimple_call_set_arg (stmt, 0, build_fold_addr_expr (tem));
+       /* Initialize tem, ptr has to be unchanged if posix_memalloc fails.  */
+       stmt = gimple_build_assign (ptr,
+ 				  fold_build2 (MEM_REF, ptr_type_node, pptr,
+ 					       build_int_cst (ptr_type_node, 0)));
+       gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
+       stmt = gimple_build_assign (tem, ptr);
+       gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
        stmt = gimple_build_assign (ptr, tem);
      }
    else
Index: gcc/testsuite/gcc.dg/torture/pr60092.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr60092.c	(revision 0)
--- gcc/testsuite/gcc.dg/torture/pr60092.c	(working copy)
***************
*** 0 ****
--- 1,21 ----
+ /* { dg-do run } */
+ /* { dg-require-weak "" } */
+ 
+ typedef __SIZE_TYPE__ size_t;
+ extern int posix_memalign(void **memptr, size_t alignment, size_t size) __attribute__((weak));
+ extern void abort(void);
+ int
+ main (void)
+ {
+   void *p;
+   int ret;
+ 
+   if (!posix_memalign)
+     return 0;
+ 
+   p = (void *)&ret;
+   ret = posix_memalign (&p, sizeof (void *), -1);
+   if (p != (void *)&ret)
+     abort ();
+   return 0;
+ }