[gcc r12-7833] PR middle-end/104885: Fix ICE with large stack frame on powerpc64.

[gcc r12-7833] PR middle-end/104885: Fix ICE with large stack frame on powerpc64.

[Roger Sayle]

https://gcc.gnu.org/g:41d1f11f5f693a2a06c65c9467a28dfeb02aed85

commit r12-7833-g41d1f11f5f693a2a06c65c9467a28dfeb02aed85
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Sat Mar 26 08:10:27 2022 -1000

    PR middle-end/104885: Fix ICE with large stack frame on powerpc64.
    
    My recent testcase for PR c++/84964.C stress tests the middle-end by
    attempting to pass a UINT_MAX sized structure on the stack.  Although
    my fix to PR84964 avoids the ICE after sorry on x86_64 and similar
    targets, a related issue still exists on powerpc64 (and similar
    ACCUMULATE_OUTGOING_ARGS/ARGS_GROW_DOWNWARD targets) which don't
    issue a "sorry, unimplemented" message, but instead ICE elsewhere.
    
    After attempting several alternate fixes, the simplest solution is
    to just defensively check in mark_stack_region_used that the upper
    bound of the region lies within the allocated stack_usage_map
    array, which is of size highest_outgoing_arg_in_use.  When this isn't
    the case, the code now follows the same path as for variable sized
    regions, and uses stack_usage_watermark rather than a map.
    
    2022-03-26  Roger Sayle  <roger@nextmovesoftware.com>
    
    gcc/ChangeLog
            PR middle-end/104885
            * calls.cc (mark_stack_region_used): Check that the region
            is within the allocated size of stack_usage_map.

Diff:
---
 gcc/calls.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/calls.cc b/gcc/calls.cc
index e13469cfd43..4d0bc45be28 100644
--- a/gcc/calls.cc
+++ b/gcc/calls.cc
@@ -201,7 +201,8 @@ mark_stack_region_used (poly_uint64 lower_bound, poly_uint64 upper_bound)
 {
   unsigned HOST_WIDE_INT const_lower, const_upper;
   const_lower = constant_lower_bound (lower_bound);
-  if (upper_bound.is_constant (&const_upper))
+  if (upper_bound.is_constant (&const_upper)
+      && const_upper <= highest_outgoing_arg_in_use)
     for (unsigned HOST_WIDE_INT i = const_lower; i < const_upper; ++i)
       stack_usage_map[i] = 1;
   else