[Bug c++/101736] New: Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[Bug c++/101736] New: Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[rsundahl at icloud dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

            Bug ID: 101736
           Summary: Option -fno-reorder-functions breaks exceptions in gcc
                    8.2.1
           Product: gcc
           Version: 8.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rsundahl at icloud dot com
  Target Milestone: ---

Created attachment 51245
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51245&action=edit
This is the source file

bash-4.4# g++ -v -save-temps -O2 -fno-reorder-functions
t-do-exceptions-work-at-all-with-this-compiler.cc && ./a.out    
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,fortran,lto --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-shared --enable-threads=posix --enable-checking=release
--enable-multilib --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-gnu-unique-object
--enable-linker-build-id --with-gcc-major-version-only
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl
--disable-libmpx --enable-offload-targets=nvptx-none --without-cuda-driver
--enable-gnu-indirect-function --enable-cet --with-tune=generic
--with-arch_32=x86-64 --build=x86_64-redhat-linux
Thread model: posix
gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-fno-reorder-functions'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/8/cc1plus -E -quiet -v -D_GNU_SOURCE
t-do-exceptions-work-at-all-with-this-compiler.cc -mtune=generic -march=x86-64
-fno-reorder-functions -O2 -fpch-preprocess -o
t-do-exceptions-work-at-all-with-this-compiler.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/8/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/8/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8

/usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/8/../../../../include/c++/8/backward
 /usr/lib/gcc/x86_64-redhat-linux/8/include
 /usr/local/include
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-fno-reorder-functions'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/8/cc1plus -fpreprocessed
t-do-exceptions-work-at-all-with-this-compiler.ii -quiet -dumpbase
t-do-exceptions-work-at-all-with-this-compiler.cc -mtune=generic -march=x86-64
-auxbase t-do-exceptions-work-at-all-with-this-compiler -O2 -version
-fno-reorder-functions -o t-do-exceptions-work-at-all-with-this-compiler.s
GNU C++14 (GCC) version 8.4.1 20200928 (Red Hat 8.4.1-1) (x86_64-redhat-linux)
        compiled by GNU C version 8.4.1 20200928 (Red Hat 8.4.1-1), GMP version
6.1.2, MPFR version 3.1.6-p2, MPC version 1.0.2, isl version isl-0.16.1-GMP

warning: MPC header version 1.0.2 differs from library version 1.1.0.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++14 (GCC) version 8.4.1 20200928 (Red Hat 8.4.1-1) (x86_64-redhat-linux)
        compiled by GNU C version 8.4.1 20200928 (Red Hat 8.4.1-1), GMP version
6.1.2, MPFR version 3.1.6-p2, MPC version 1.0.2, isl version isl-0.16.1-GMP

warning: MPC header version 1.0.2 differs from library version 1.1.0.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 38c2e671f40afe50da0df14ae856e910
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-fno-reorder-functions'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
 as -v --64 -o t-do-exceptions-work-at-all-with-this-compiler.o
t-do-exceptions-work-at-all-with-this-compiler.s
GNU assembler version 2.30 (x86_64-redhat-linux) using BFD version version
2.30-93.el8
COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/8/:/usr/libexec/gcc/x86_64-redhat-linux/8/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/8/:/usr/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/8/:/usr/lib/gcc/x86_64-redhat-linux/8/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-fno-reorder-functions'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/8/collect2 -plugin
/usr/libexec/gcc/x86_64-redhat-linux/8/liblto_plugin.so
-plugin-opt=/usr/libexec/gcc/x86_64-redhat-linux/8/lto-wrapper
-plugin-opt=-fresolution=t-do-exceptions-work-at-all-with-this-compiler.res
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc --build-id --no-add-needed --eh-frame-hdr
--hash-style=gnu -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/gcc/x86_64-redhat-linux/8/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-redhat-linux/8/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-redhat-linux/8/crtbegin.o
-L/usr/lib/gcc/x86_64-redhat-linux/8
-L/usr/lib/gcc/x86_64-redhat-linux/8/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/8/../../..
t-do-exceptions-work-at-all-with-this-compiler.o -lstdc++ -lm -lgcc_s -lgcc -lc
-lgcc_s -lgcc /usr/lib/gcc/x86_64-redhat-linux/8/crtend.o
/usr/lib/gcc/x86_64-redhat-linux/8/../../../../lib64/crtn.o
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-fno-reorder-functions'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'

terminate called after throwing an instance of 'std::invalid_argument'
  what():  Test
Aborted

NOTE: Also confirmed with:
g++-8 (Ubuntu 8.4.0-1ubuntu1~18.04) 8.4.0
g++ (GCC) 8.2.1 20180905 (Red Hat 8.2.1-3)

[Bug c++/101736] Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[rsundahl at icloud dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

--- Comment #1 from Roy Sundahl <rsundahl at icloud dot com> ---
Created attachment 51246
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51246&action=edit
This is the preprocessed file (.ii)

[Bug c++/101736] Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Seems to work in GCC 9 but GCC 9 does not do the partitioning of the function
so ...

[Bug rtl-optimization/101736] Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
A workaround is to do -fno-reorder-blocks-and-partition if you do
-fno-reorder-function

[Bug rtl-optimization/101736] Option -fno-reorder-functions breaks exceptions in gcc 8.2.1

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-08-02
     Ever confirmed|0                           |1

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is a testcase which fails on the trunk still:
inline void
throw_expr ()
{
  throw 0;
}

void f(void) __attribute__((hot));
void f(void) {}

using namespace std;

int main1 (int t) __attribute__((noinline, hot));
int
main1 (int t)
{
  if (t) { f(); return 0;}
  try
  {
    throw_expr();
  }
  catch (int) { }
  return 0;
}
int main(void)
{
    return main1(0);
}
---------- CUT ------
I had to add some extra functions to force the partitioning to happen.

>From what I can tell -freorder-blocks-and-partition should be turned off if
-freorder-function is turned off.

[Bug rtl-optimization/101736] Option -fno-reorder-functions breaks exceptions

[rsundahl at icloud dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

--- Comment #5 from Roy Sundahl <rsundahl at icloud dot com> ---
(In reply to Andrew Pinski from comment #3)
> A workaround is to do -fno-reorder-blocks-and-partition if you do
> -fno-reorder-function

That worked! Many thanks Andrew for vetting this bug so quickly and suggesting
this workaround. It is greatly appreciated.

[Bug rtl-optimization/101736] Option -fno-reorder-functions breaks exceptions

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101736

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
We do

  if (opts->x_flag_reorder_blocks_and_partition)
    SET_OPTION_IF_UNSET (opts, opts_set, flag_reorder_functions, 1);

I guess that needs to be adjusted to disable -freorder-blocks-and-partition
when -freorder-functions is explicitely unset.

section *
default_function_section (tree decl, enum node_frequency freq,
                          bool startup, bool exit)
{
...
  if (!flag_reorder_functions
      || !targetm_common.have_named_sections)
    return NULL;

might be the actual issue though (the only user of the flag I can find)