[Bug c++/77681] New: failing to inline simple function when using -fgnu-tm

["pc at us dot ibm.com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77681

            Bug ID: 77681
           Summary: failing to inline simple function when using -fgnu-tm
           Product: gcc
           Version: 6.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pc at us dot ibm.com
  Target Milestone: ---

Created attachment 39671
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39671&action=edit
testcase where always_inline fails with -fgnu-tm

I've used several different versions of GCC, including 4.8.5 and 6.2.1, on
different architectures (x86_64 and ppc64le).

I first noticed that a very simple "static inline" function was not being
inlined.  When I added "__attribute__((always_inline))", an error was produced
(see below). In narrowing down the testcase, I also tried to narrow down the
command line, and discovered that the error is only produced when "-fgnu-tm" is
present.  The narrowed-down testcase makes no use of transactional memory, so
there appears to be some inlining interference caused by "-fgnu-tm".
--
$ g++ -O3 -c always-inline.cpp -fgnu-tm -o /dev/null
always-inline.cpp: In member function ‘T* spsc<T>::pop() [with T = int]’:
always-inline.cpp:9:1: error: inlining failed in call to always_inline ‘void*
_ZL13SPHGetFreePtrPv.constprop.0()’: 
 SPHGetFreePtr (void *H) {
 ^
always-inline.cpp:19:32: error: called from here
   T** p = (T**) SPHGetFreePtr(0);
$ g++ -O3 -c always-inline.cpp -o /dev/null
$
--