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From: "xvladsoft at yahoo dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/109554] New: Compiler generates incorrect code when the
 function declared with returned parameterm but no 'return' in its body
Date: Wed, 19 Apr 2023 11:47:29 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109554

            Bug ID: 109554
           Summary: Compiler generates incorrect code when the function
                    declared with returned parameterm but no 'return' in
                    its body
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xvladsoft at yahoo dot com
  Target Milestone: ---

Created attachment 54883
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54883&action=3Dedit
The source file which shows issue.

Good day!

First of all, thanks alot for you efforts to create so nice compiler! It is
really nice: generates small and fast code!

But looks like I found an issue: the compiler does not generate a 'return
point' where the function is declared with not-void return parameter, but no
'return' operators in its body.

Details:
  *** 1) Operation system:
uname -a
Linux XVlad-Work 4.19.0-22-amd64 #1 SMP Debian 4.19.260-1 (2022-09-29) x86_=
64
GNU/Linux
  *** 2) Compiler version (according to https://gcc.godbolt.org/ issue
reproduces from 8.3.0 till the latest (12.+)):
gcc -v
Using built-in specs.
COLLECT_GCC=3Dgcc
COLLECT_LTO_WRAPPER=3D/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=3Dnvptx-none
OFFLOAD_TARGET_DEFAULT=3D1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion=3D'Debian 8.3.0-6'
--with-bugurl=3Dfile:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=3Dc,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=3D/u=
sr
--with-gcc-major-version-only --program-suffix=3D-8
--program-prefix=3Dx86_64-linux-gnu- --enable-shared --enable-linker-build-=
id
--libexecdir=3D/usr/lib --without-included-gettext --enable-threads=3Dposix
--libdir=3D/usr/lib --enable-nls --enable-bootstrap --enable-clocale=3Dgnu
--enable-libstdcxx-debug --enable-libstdcxx-time=3Dyes
--with-default-libstdcxx-abi=3Dnew --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=3Dauto
--enable-multiarch --disable-werror --with-arch-32=3Di686 --with-abi=3Dm64
--with-multilib-list=3Dm32,m64,mx32 --enable-multilib --with-tune=3Dgeneric
--enable-offload-targets=3Dnvptx-none --without-cuda-driver
--enable-checking=3Drelease --build=3Dx86_64-linux-gnu --host=3Dx86_64-linu=
x-gnu
--target=3Dx86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Debian 8.3.0-6)=20

  *** 3) Command line to compile:
gcc -O3 ./SandBox_2.cpp
  *** 4) Command line to execute:
./a.out 0

Observations:
Please, look at the code in the attached file:=20
 - when it is compiled as:
/GccBug$ gcc -O0 ./SandBox_2.cpp
 - program executes correctly:
/GccBug$ ./a.out 0
Hello world from SandBox-2!
8.3.0
Point-A 0, 0
 - *BUT* when it is compiled as:
/GccBug$ gcc -O3 ./SandBox_2.cpp
 - program crashes:
/GccBug$ ./a.out 0
Hello world from SandBox-2!
8.3.0
Point-A 0, 0
Point-B 1, 0
Segmentation fault    <<<!!!!!!!


Best regards,
Vladimir.=