OpenRISC GCC Status Update - shorne in japan

News flash, the OpenRISC GCC port now can run “Hello World”

After about 4 months of development on the OpenRISC GCC port rewrite I have hit my first major milestone, the “Hello World” program is working. Over those 4 months I spent about 2 months working on my from scratch dummy SMH port then 2 months to get the OpenRISC port to this stage.

Next Steps

There are still many todo items before this will be ready for general use, including:

Milestone 2 items
- Investigate and Fix test suite failures, see below
- Write OpenRISC specific test cases
- Ensure all memory layout and calling conventions are within spec
- Ensure sign extending, overflow, and carry flag arithmetic is correct
- Fix issues with GDB debugging target remote is working OK, target sim is having issues.
- Implement stubbed todo items, see below
- Support for C++, I haven’t even tried to compile it yet
Milestone 3 items
- Support for position independent code (PIC)
- Support for thread local storage (TLS)
- Support for floating point instructions (FPU)
- Support for Atomic Builtins

Somewhere between milestone 2 and 3 I will start to work on getting the port reviewed on the GCC and OpenRISC mailing lists. If anyone wants to review right now please feel free to send feedback.

Test Suite Results

Running the gcc testsuite right now shows the following results. Many of these look to be related to internal compiler errors.

                === gcc Summary ===

# of expected passes            84301
# of unexpected failures        5096
# of unexpected successes       3
# of expected failures          211
# of unresolved testcases       2821
# of unsupported tests          2630
/home/shorne/work/gnu-toolchain/build-gcc/gcc/xgcc  version 9.0.0 20180426 (experimental) (GCC)

Stubbed TODO Items

Some of the stubbed todo items include:

Trampoline Handling

In gcc/config/or1k/or1k.h implement trampoline hooks for nested functions.

#define TRAMPOLINE_SIZE 12
#define TRAMPOLINE_ALIGNMENT (abort (), 0)

Profiler Hooks

In gcc/config/or1k/or1k.h implement profiling hooks.

#define FUNCTION_PROFILER(FILE,LABELNO) (abort (), 0)

Exception Handler Hooks

In gcc/config/or1k/or1k.c ensure what I am doing is right, on other targets they copy the address onto the stack before returning.

/* TODO, do we need to just set to r9? or should we put it to where r9
   is stored on the stack?  */
void
or1k_expand_eh_return (rtx eh_addr)
{
  emit_move_insn (gen_rtx_REG (Pmode, LR_REGNUM), eh_addr);
}