toolchain/gcc/patches/11.2.0/001-v11.3.0-ranger-Fix-up-fold_using_range-range_of_address-PR10.patch

   1 From a6219e8e0719b14f474b0dcaa7bde2f4e57474f9 Mon Sep 17 00:00:00 2001
   2 From: Jakub Jelinek <jakub@redhat.com>
   3 Date: Wed, 17 Nov 2021 13:45:53 +0100
   4 Subject: [PATCH] ranger: Fix up fold_using_range::range_of_address [PR103255]
   5
   6 If on &base->member the offset isn't constant or isn't zero and
   7 -fdelete-null-pointer-checks and not -fwrapv-pointer and base has a range
   8 that doesn't include NULL, we return the range of the base.
   9 Usually it isn't a big deal, because for most pointers we just use
  10 varying, range_zero and range_nonzero ranges and nothing beyond that,
  11 but if a pointer is initialized from a constant, we actually track the
  12 exact range and in that case this causes miscompilation.
  13 As discussed on IRC, I think doing something like:
  14               offset_int off2;
  15               if (off_cst && off.is_constant (&off2))
  16                 {
  17                   tree cst = wide_int_to_tree (sizetype, off2 / BITS_PER_UNIT);
  18                   // adjust range r with POINTER_PLUS_EXPR cst
  19                   if (!range_includes_zero_p (&r))
  20                     return true;
  21                 }
  22               // Fallback
  23               r = range_nonzero (TREE_TYPE (gimple_assign_rhs1 (stmt)));
  24               return true;
  25 could work, given that most of the pointer ranges are just the simple ones
  26 perhaps it is too much for little benefit.
  27
  28 2021-11-17  Jakub Jelinek  <jakub@redhat.com>
  29
  30         PR tree-optimization/103255
  31         * gimple-range.cc (fold_using_range::range_of_address): Return
  32         range_nonzero rather than unadjusted base's range.  Formatting fixes.
  33
  34         * gcc.c-torture/execute/pr103255.c: New test.
  35
  36 (cherry picked from commit c39cb6bf835ca12e590eaa6f90222e51be207c50)
  37 ---
  38  gcc/gimple-range.cc                           | 16 +++++---
  39  .../gcc.c-torture/execute/pr103255.c          | 41 +++++++++++++++++++
  40  2 files changed, 52 insertions(+), 5 deletions(-)
  41  create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr103255.c
  42
  43 --- a/gcc/gimple-range.cc
  44 +++ b/gcc/gimple-range.cc
  45 @@ -491,14 +491,20 @@ gimple_ranger::range_of_address (irange
  46         }
  47        /* If &X->a is equal to X, the range of X is the result.  */
  48        if (off_cst && known_eq (off, 0))
  49 -         return true;
  50 +       return true;
  51        else if (flag_delete_null_pointer_checks
  52                && !TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
  53         {
  54 -        /* For -fdelete-null-pointer-checks -fno-wrapv-pointer we don't
  55 -        allow going from non-NULL pointer to NULL.  */
  56 -          if(!range_includes_zero_p (&r))
  57 -           return true;
  58 +         /* For -fdelete-null-pointer-checks -fno-wrapv-pointer we don't
  59 +            allow going from non-NULL pointer to NULL.  */
  60 +         if (!range_includes_zero_p (&r))
  61 +           {
  62 +             /* We could here instead adjust r by off >> LOG2_BITS_PER_UNIT
  63 +                using POINTER_PLUS_EXPR if off_cst and just fall back to
  64 +                this.  */
  65 +             r = range_nonzero (TREE_TYPE (gimple_assign_rhs1 (stmt)));
  66 +             return true;
  67 +           }
  68         }
  69        /* If MEM_REF has a "positive" offset, consider it non-NULL
  70          always, for -fdelete-null-pointer-checks also "negative"
  71 --- /dev/null
  72 +++ b/gcc/testsuite/gcc.c-torture/execute/pr103255.c
  73 @@ -0,0 +1,41 @@
  74 +/* PR tree-optimization/103255 */
  75 +
  76 +struct H
  77 +{
  78 +  unsigned a;
  79 +  unsigned b;
  80 +  unsigned c;
  81 +};
  82 +
  83 +#if __SIZEOF_POINTER__ >= 4
  84 +#define ADDR 0x400000
  85 +#else
  86 +#define ADDR 0x4000
  87 +#endif
  88 +#define OFF 0x20
  89 +
  90 +int
  91 +main ()
  92 +{
  93 +  struct H *h = 0;
  94 +  unsigned long o;
  95 +  volatile int t = 1;
  96 +
  97 +  for (o = OFF; o <= OFF; o += 0x1000)
  98 +    {
  99 +      struct H *u;
 100 +      u = (struct H *) (ADDR + o);
 101 +      if (t)
 102 +       {
 103 +         h = u;
 104 +         break;
 105 +       }
 106 +    }
 107 +
 108 +  if (h == 0)
 109 +    return 0;
 110 +  unsigned *tt = &h->b;
 111 +  if ((__SIZE_TYPE__) tt != (ADDR + OFF + __builtin_offsetof (struct H, b)))
 112 +    __builtin_abort ();
 113 +  return 0;
 114 +}