Added optimizations for (char)X = (int)X >> N
I need to do the complementary left-shift forms

Found another problem. Byte AND immediate operations were operating on the low byte. This resulted in odd behavior, and took a while to track down. All fixed now.

Now that Thanksgiving is over, I can get back to TI stuff. I'm using the LIBC project as a larger test program for GCC. Good thing too.

I found and removed a byte compare form which used a constant. I'm not sure how that got there. Copy-paste error maybe?

I've noticed that there's a lot of emitted code like this for int-to-char conversions:
mov r1, r2
mov r2, r1
swpb r1

And then R2 is never used again. I can do better than that, so an optimization has been added to handle this case. Now we get:
swpb r1

Much better. So now it's time for byte compare optimizations. I want to change:
li r2, >1200
cb r1, r2
jh LABEL
to:
ci r1, >12FF
jh LABEL

This is what I wrote for the patch release at AtariAge:

Well, it's patch time again.

Here's what made it into this release:

Bintils
Allow TI-style quotes ('example')
Allow two-byte character constants for immediate expressions (li r0, 'ab')
Fix a BFD Makefile bug which prevented clean compilation

GCC
Fix tms9900_output_ascii, was emitting invalid code when non-text characters were used
Divide and modulus operations now merged when possible
Fix data symbol declarations, now TI compliant
Fix "+=4" form, was missing comma in emitted code
Fix alignment of code, in some cases it was possible to misalign code by using odd-length string constants
Fix stack frame load/save differences, was using different locations between function prologue and epilogue in some cases (Thanks Tursi!)
Save return pointer at bottom of stack. This may help for later stack trace construction
Add optimizations for compare-and-branch operations with 16-bit values against -2, -1, 0, 1, and 2.

Right now I only have optimizations for equality tests with -2, -1, 1, and 2 done. To get inequality tests, I need to convince GCC to emit tests against the overflow flag. GCC has no concept of this kind of instruction, so I need to play with that a bit more.

The other weakness is the divide and modulus instructions. I haven't been able to convince GCC to use convenient registers for the source and destination. This means that in some cases, I need to insert additional MOVs which really shouldn't be necessary. More playing around required here too, I suppose.

I've addressed all the problems Tursi found earlier, plus a few others. Unfortunately, libiberty is not on that list. Since a lot of those routines are OS-specific, and since there is no POSIX-like interface for the TI, these functions are of limited use right now. In the future that might change. (hint, hint)

So here's the build procedure for everything. I've made sure these have been tested several times. There should be no problems following them.


Patching the original files:
$ cd binutils-2.19.1
$ patch -p1 < binutils-2.19.1-tms9900-1.1.patch

$ cd gcc-4.4.0
$ patch -p1 < gcc-4.4.0-tms9900-1.2.patch

Building binutils
$ ./configure --target tms9900 --prefix INSTALLDIR
$ make all
$ make install

Building GCC
$ ./configure --target=tms9900 --prefix=INSTALLDIR --enable-languages=c
$ make all-gcc
$ make install

Notice that GCC uses equals after the options, while binutils does not. Kind of annoying and easy to mix up. At this point, you will have all the GNU compilation tools ready to use for TI work. The binary format is ELF, since that stores the extra data needed by the linker and other tools. In earlier posts I've attached code to convert from ELF to TI-cart format. I've also got prototype converters for EA5 and EA3 formats too, but I haven't tested them very much.

When compiling with GCC, I recommend using the -O2 and/or -Os options to reduce the overall code size. Using the default options can result in extra wordy code with unnecessary or duplicate instructions.

There's still quite a bit of work left to do for GCC, so there will be more patches coming. I need to fill out the missing math support for 32-bit values, make sure signed multiply and divide work, and the other stuff mentioned above. I especially want to add more optimizations to the compiled output, but that will come as I get more familiar with what instruction patterns GCC likes to use.

So I've make scripts to automate making patches. Not very fast, but that's OK for now.

I found and fixed the build problem in binutils. It turns out that there was a missing recipie for elf32-tms9900.lo in bfd/Makefile.in. Fixing this problem allows binutils to build without any problems.

For future reference:

patching:
$ cd {path_to_original_files}
$ patch -p1 < patchfile

binutils:
$ ./configure --target tms9900 --prefix /home/eric/dev/tios/toolchain/WORKSPACE/emw
$ make all
$ make install


GCC:
$ ./configure --prefix /home/eric/dev/tios/toolchain --target=tms9900 --enable-languages=c
$ make all-gcc
$ make install

Tomorrow, I'll confirm that the build tools work as advertised and release.

The INC-type comprisons have been made and tested. I looked into getting JNO working, and found a good template in the Sparc archetecture. I decided against doing anything about that right now. I need to get a patch out now. New features can wait a bit.

I decided to run a test to make sure that everything was working before making patches, and I'm glad I did. Apparently, I made changes to GAS a while ago to allow TI-style constants. In the process, I broke processing for all other types of constants. The resulting binaries were unusable, and caused crashes and resets. Thst's been fixed, and all my testing looks OK, so I'm off to make patches.

More problems. The scripts I thought I had to make patches, are not complete. Even worse, I don't remember what the missing pieces were. That means I need to start over from scratch. Poop.

I also need to keep the blog site up-to-date and advertise it in an AtariAge sig. Not really necessary, but someone might be interested.

No, I made the same mistake agin. I can't use INC and friends for comparison due to the possible overflow. I can only use those forms for equality tests. I should be able to do the other tests if I can use the JNO instruction. I don't have the motivation to add that right now.