[Bug tree-optimization/97424] New: Warn on invalid shift amount after inlining

[fw at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97424

            Bug ID: 97424
           Summary: Warn on invalid shift amount after inlining
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fw at gcc dot gnu.org
  Target Milestone: ---

Consider this program:

#include <stdint.h>

static inline uint32_t
_dl_hwcaps_subdirs_build_bitmask (int subdirs, int active)
{
  /* Leading subdirectories that are not active.  */
  int inactive = subdirs - active;
  if (inactive == 32)
    return 0;

  uint32_t mask;
  if (subdirs != 32)
    mask = (1 << subdirs) - 1;
  else
    mask = -1;
  return mask ^ ((1U << inactive) - 1);
}

void f1 (int);

void
f2 (void)
{
  f1 (_dl_hwcaps_subdirs_build_bitmask (1, 2));
  f1 (_dl_hwcaps_subdirs_build_bitmask (33, 31));
}

This has invalid shifts involving a negative shift amount and larger-than-width
shift amount. This does not result in a warning because the current shift
warnings are implemented in the front end. But the computed values as the
argument to f1 are garbage, so it would make sense to warn.