https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103562
Bug ID: 103562
Summary: Jitted code produces incorrect result when returning
3-member struct from internal function
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: jit
Assignee: dmalcolm at gcc dot gnu.org
Reporter: andy.pj.hanson at gmail dot com
Target Milestone: ---
Created attachment 51927
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51927&action=edit
File that reproduces the bug
See the attached program `jit_error.c`. To reproduce, run: `gcc jit_error.c
-lgccjit && ./a.out`. This will output: `get_a(&s) is 140730936729392` (or some
other large number); The correct output would be 1.
The file should JIT a program like this:
```
struct my_struct { long a; long b; long c; };
struct my_struct deref(struct my_struct *ptr) { return *ptr; }
long get_a(struct my_struct *s) { return deref(s).a; }
```
For some reason, the function `deref` is optimized in an invalid way.
The bug goes away (and the program correctly outputs 1) if you do any one of
the following:
* Set GCC_JIT_INT_OPTION_OPTIMIZATION_LEVEL to 0.
* Remove the `c` field.
* Change `func_deref` from `GCC_JIT_FUNCTION_INTERNAL` to
`GCC_JIT_FUNCTION_EXPORTED`.
* Inline the call using `gcc_jit_rvalue *callDeref =
gcc_jit_lvalue_as_rvalue(gcc_jit_rvalue_dereference(gcc_jit_param_as_rvalue(param_get_a),
NULL));`.
* Use `GCC_JIT_TYPE_INT` instead of `GCC_JIT_TYPE_LONG`.
I've tested this the GCC master branch as of 20211204, and with OpenSUSE's GCC
version.
My `gcc -v` is:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/andy/temp/gccjitrepro2/install/libexec/gcc/x86_64-pc-linux-gnu/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../src/configure --enable-host-shared
--enable-languages=jit,c++ --disable-bootstrap --disable-shared
--prefix=/home/andy/temp/gccjitrepro2/install
--with-gmp=/home/andy/temp/gccjitrepro2/build-gmp
--with-isl==/home/andy/temp/gccjitrepro2/build-isl
--with-mpfr=/home/andy/temp/gccjitrepro2/build-mpfr
--with-mpc=/home/andy/temp/gccjitrepro2/build-mpc
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20211204 (experimental) (GCC)
