102 lines
3.5 KiB
Markdown
102 lines
3.5 KiB
Markdown
# llvm816
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LLVM/Clang C compiler for the WDC 65816 / Apple IIgs.
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Compiles C (and a minimal subset of C++) to native 65816 machine code,
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links to a relocatable OMF binary, and runs under MAME's apple2gs.
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Speed-tuned: matches or beats hand-written 65816 assembly on the
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tight loops in benchmarks like sumOfSquares, popcount, and strcpy.
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## What you get
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- **`clang --target=w65816`** — full C99 + parts of C11, optimized at
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`-O2` by default. Soft-float and soft-double included.
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- **C standard library subset** — `stdio.h`, `stdlib.h`, `string.h`,
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`math.h`, `time.h`, `setjmp.h`, etc. See
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[`runtime/include/`](runtime/include/) for the complete list.
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- **`link816`** — relocating linker producing GS/OS-loadable OMF
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binaries (single- or multi-segment).
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- **MAME integration scripts** — compile, link, and run a program
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under MAME's apple2gs with one command.
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- **Apple IIgs Toolbox bindings** — `<iigs/toolbox_full.h>` exposes
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~1300 toolbox routines from 35 tool sets.
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## Quick start
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After installation (see [docs/INSTALL.md](docs/INSTALL.md)):
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```bash
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# Compile a C file
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cat > hello.c <<'EOF'
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__attribute__((noinline)) void switchToBank2(void) {
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__asm__ volatile ("sep #0x20\n.byte 0xa9,0x02\npha\nplb\nrep #0x20\n");
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}
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int main(void) {
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unsigned short x = 0;
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for (int i = 1; i <= 10; i++) x += i; // x = 55
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switchToBank2();
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*(volatile unsigned short *)0x5000 = x;
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while (1) {}
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}
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EOF
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# Build + run under MAME (writes 0x0037 to $025000, MAME displays it)
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./tools/llvm-mos-build/bin/clang --target=w65816 -O2 -c hello.c -o hello.o
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./tools/link816 -o hello.bin --text-base 0x1000 \
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runtime/crt0.o runtime/libc.o runtime/libgcc.o hello.o
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bash scripts/runInMame.sh hello.bin --check 0x025000=0037
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```
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See [docs/USAGE.md](docs/USAGE.md) for a full walkthrough including
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multi-segment builds and the Apple IIgs Toolbox.
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## Project layout
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```
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runtime/ C standard library + crt0 startup
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src/ sources (C and .s)
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include/ headers
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*.o built object files
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src/ our LLVM/Clang sources (W65816 target backend)
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clang/ clang patches
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llvm/ LLVM patches + W65816 target
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link816/ relocating linker
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patches/ patches against vanilla llvm-mos
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scripts/ install scripts, MAME runners, benchmarks
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tools/ installed compilers, MAME, ROMs, Calypsi (reference)
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benchmarks/ cycle-count and instruction-count benchmarks
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compare/ side-by-side asm vs Calypsi
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docs/ this directory — INSTALL.md, USAGE.md, design notes
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```
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## Status
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Stable enough to build real programs. Current quality vs commercial
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Calypsi 5.16 (lower is better):
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| Benchmark | Our cyc/call | Calypsi cyc/call (approx) |
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|---|---|---|
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| sumOfSquares(50) | 16709 | ~16000 |
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| popcount(0x12345678) | 2864 | ~2500 |
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| memcmp(eq, 5) | 989 | ~700 |
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| bsearch(arr, 8, 5) | 767 | ~600 |
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Static-size for the canonical `sumSquares` benchmark: 37 inst (ours)
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vs 31 inst (Calypsi) — **1.19×**.
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See [STATUS.md](STATUS.md) for full language and runtime feature
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coverage, and [LLVM_65816_DESIGN.md](LLVM_65816_DESIGN.md) for
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backend internals.
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## Documentation
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- [docs/INSTALL.md](docs/INSTALL.md) — system requirements and install
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steps
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- [docs/USAGE.md](docs/USAGE.md) — compile, link, run, debug
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- [STATUS.md](STATUS.md) — current language/runtime support matrix
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- [LLVM_65816_DESIGN.md](LLVM_65816_DESIGN.md) — backend design notes
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## License
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Apache 2.0 (matching the LLVM project's license). See
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`tools/llvm-mos/LICENSE.TXT` after install.
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