[Bug rtl-optimization/105091] RTL dse1 remove stack mem storing incorrectly

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105091

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-03-30

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
  <bb 3> [local count: 715863673]:
  # ivtmp_47 = PHI <1(3), 2(2)>
  _43 = ivtmp_47 * 18446744073709551544;
  GOTMP.8 = MEM[(struct  *)&GOTMP.5 + 144B + _43 * 1];
  GOTMP.13 = GOTMP.8;
  test = GOTMP.13;
  p = test.x;
  D.483.__type_descriptor = &g.type.._6_7int;
  GOTMP.14 = p;
  D.483.__object = &GOTMP.14;
  main.F (D.483);
  p ={v} {CLOBBER(eol)};
  if (ivtmp_47 != 1)
    goto <bb 3>; [66.67%]
  else
    goto <bb 4>; [33.33%]

  <bb 4> [local count: 357878152]:
  test ={v} {CLOBBER(eol)};
  return;

that's an interesting sequence of aggregate copies (meh - SRA should
optimize those!) and an interesting choice of IVs but nothing invalid.

We expand the

  GOTMP.8 = MEM[(struct  *)&GOTMP.5 + 144B + _43 * 1];

stmt to memcpy() but GOTMP.5 is not TREE_ADDRESSABLE here.  That might
in the end lead DSE to remove the stores.  When setting the flag
inside gdb during expansion I see the stores are retained.

Now, emit_block_op_via_libcall does

  /* Since dst and src are passed to a libcall, mark the corresponding
     tree EXPR as addressable.  */
  tree dst_expr = MEM_EXPR (dst);
  tree src_expr = MEM_EXPR (src);
  if (dst_expr)
    mark_addressable (dst_expr);
  if (src_expr)
    mark_addressable (src_expr);

but mark_addressable doesn't handle TARGET_MEM_REF.

Does the following fix the runtime error?  The RTL after DSE seems to be OK.

diff --git a/gcc/gimple-expr.cc b/gcc/gimple-expr.cc
index f9a650b5daf..5faaf43eaf5 100644
--- a/gcc/gimple-expr.cc
+++ b/gcc/gimple-expr.cc
@@ -910,7 +910,8 @@ mark_addressable (tree x)
     x = TREE_OPERAND (x, 0);
   while (handled_component_p (x))
     x = TREE_OPERAND (x, 0);
-  if (TREE_CODE (x) == MEM_REF
+  if ((TREE_CODE (x) == MEM_REF
+       || TREE_CODE (x) == TARGET_MEM_REF)
       && TREE_CODE (TREE_OPERAND (x, 0)) == ADDR_EXPR)
     x = TREE_OPERAND (TREE_OPERAND (x, 0), 0);
   if (!VAR_P (x)