[Bug middle-end/83023] New: branch probabilities pessimize malloc

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83023

            Bug ID: 83023
           Summary: branch probabilities pessimize malloc
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nathan at gcc dot gnu.org
  Target Milestone: ---

Created attachment 42625
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42625&action=edit
exemplar

on x86_64 compiled with -O2 -fdump-tree-all, the ma.cc.046t.profile_estimate
contains:
  r_5 = malloc (s_3(D));
  if (r_5 != 0B)
    goto <bb 3>; [53.47%]
  else
    goto <bb 4>; [46.53%]

That's a pretty inaccurate guess at the behaviour of malloc!