a1647eab9b
Step 3b code is wired across UIRenderer + GlyphCache + UIPipeline +
chess game (gpu_mode = .metal on iOS, MetalGPU bound via the GPU
protocol). macOS GL chess, iOS-sim GLES chess, and iOS-sim Metal
triangle (63-metal-clear.sx) all still render.
iOS-sim Metal chess crashes inside replaceRegion uploading the 1MB
font atlas. Bisecting that crash exposed several sx-language issues
where mid-bisect tracers (NSLog inside if/else branch bodies) didn't
produce output, blocking further investigation.
Filing each finding as examples/issue-NNNN.sx rather than working
around piecemeal:
Bugs:
- 0024 NSLog/foreign-call inside if/else body not producing output
- 0025 C-ABI param coercion incomplete for composites >16B
(combined direct-call abiCoerceParamType TODO + call_indirect
path that doesn't apply C-ABI coercion at all)
- 0026 replaceRegion 1MB upload crash (likely downstream of 0025)
Features needed for step 4 + cleanup:
- 0027 Obj-C block bridge (^{...}) for animateWithDuration:
- 0028 Optional protocol box (?GPU = null) replaces T = ---; has_T: bool
- 0029 destroy_texture/buffer/shader on GPU protocol
- 0030 extern cross-file globals
Library-side: renderer.sx + glyph_cache.sx + pipeline.sx gain a
`gpu: GPU = ---; has_gpu: bool` field pair + branches that route every
GL touchpoint through the protocol when has_gpu. glyph_cache.init
saves/restores those fields around its memset. pipeline.set_gpu()
propagates to renderer + font. Renderer's MSL shader source added as
UI_MSL_SRC using packed_float2/packed_float4 to keep the 12-float
interleaved vertex layout tight (48 bytes).
metal.sx: dual-phase init (init(null, 0, 0) for eager device+queue,
re-init with the layer once UIKit installs the SxMetalView).
setStorageMode:.shared on every texture descriptor to ensure CPU-
writable atlas pixels on Apple Silicon iOS-sim.
Regression suite: 68 passing, 0 failed. WASM chess build currently
broken under step 3b state (silent compiler crash); documented in
CHECKPOINT.md, likely fallout from one of the filed issues (probably
0028 — the verbose protocol-box pattern). Step 3b resumes after
0024-0030 land.
95 lines
4.5 KiB
Plaintext
95 lines
4.5 KiB
Plaintext
// issue-0025: Composite types larger than 16 bytes are passed without the
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// LLVM `byval(<ty>)` attribute, and the `call_indirect` (fn-pointer cast)
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// path doesn't apply C-ABI parameter coercion at all. Both gaps cause
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// silent shape-mismatch when sx code calls foreign C functions that take
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// large aggregates by value, OR when sx code calls a sx fn through a
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// fn-pointer typed with a large-aggregate parameter.
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//
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// ── Two failing forms ─────────────────────────────────────────────────────
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//
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// (A) Direct call to a sx function with a >16B param:
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//
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// Wide :: struct { a: s64; b: s64; c: s64; d: s64; } // 32 bytes
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// accept :: (w: Wide) -> s64 { w.a + w.b + w.c + w.d; }
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// accept(Wide.{ a = 1, b = 10, c = 100, d = 1000 }) // expect 1111
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//
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// src/ir/emit_llvm.zig:2747-2795 (`abiCoerceParamType`):
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// - <=8 bytes → coerced to i64
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// - 9-16 bytes → coerced to [2 x i64]
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// - >16 bytes → returns llvm_ty unchanged with TODO at line 2793
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//
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// The TODO is the bug: large composites should be coerced to `ptr`
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// with a `byval(struct.T)` LLVM attribute. LLVM's mid-end then
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// materializes the right machine code per target. Today the struct
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// is left as-is, which LLVM tries to pass across registers + stack
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// slots in ways that don't match the C ABI promise.
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//
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// (B) Indirect call via fn-pointer cast (the `xx objc_msgSend` idiom):
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//
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// fn_ptr : (Wide) -> s64 = xx accept;
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// fn_ptr(Wide.{ ... })
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//
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// src/ir/emit_llvm.zig:902-967 (`.call_indirect`): both the
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// FunctionInfo-known arm (939-952) and the LLVMTypeOf-fallback arm
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// (953-956) construct `param_tys[j]` WITHOUT routing through
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// `abiCoerceParamType`. So even if (A) is fixed, fn-pointer-cast call
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// sites still mis-marshal large composites.
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//
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// ── Real-world impact ──────────────────────────────────────────────────────
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//
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// Every `xx objc_msgSend` call site in library/modules/platform/uikit.sx
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// + library/modules/gpu/metal.sx. Works in practice today only because:
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// - We never pass aggregates >16 bytes by value through fn-pointer casts
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// (workaround: declare param as `*T` + pass `@local`; arm64 AAPCS's
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// indirect-by-ref happens to match this machine-state-wise).
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// - HFAs (CGSize 2×f64, MTLClearColor 4×f64, CGRect 4×f64 as return)
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// are correctly classified at emit_llvm.zig:2766-2779.
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//
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// ── Workarounds in use ─────────────────────────────────────────────────────
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//
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// library/modules/gpu/metal.sx declares MTLRegion (48B) + MTLScissorRect
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// (32B) call sites with `*MTLRegion` / `*MTLScissorRect` and passes
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// `@region` / `@rect`. Should not be needed once this issue is fixed.
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//
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// ── Fix sketch ─────────────────────────────────────────────────────────────
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//
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// (A) emit_llvm.zig:2793 — return `ptr` and emit `byval(struct.T)` on
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// the param via `LLVMAddCallSiteAttribute` / `LLVMCreateTypeAttribute`.
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// At call sites, alloca + memcpy + pass the alloca pointer. Apply
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// identically at function-definition emission so direct calls roundtrip.
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//
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// (B) emit_llvm.zig:902-967 — factor out a helper
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// `coerceCallParams(param_count, src_args, dst_fn_param_tys)
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// -> (coerced_args, coerced_tys)` that wraps `abiCoerceParamType`.
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// Use the helper from both arms.
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//
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// Edge cases to preserve:
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// - Variadic foreign functions (printf family) — variadic tail per
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// AAPCS64 still passes composites in their natural form. Keep
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// existing behavior for variadic args.
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// - HFAs already handled at 2766-2779 — don't touch.
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// - Structs <=8 bytes coerced to `i64`, 9-16 bytes to `[2 x i64]` —
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// don't touch.
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#import "modules/std.sx";
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Wide :: struct {
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a: s64; b: s64; c: s64; d: s64;
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}
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accept :: (w: Wide) -> s64 {
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w.a + w.b + w.c + w.d;
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}
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main :: () -> s32 {
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w := Wide.{ a = 1, b = 10, c = 100, d = 1000 };
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direct := accept(w); // exercises path (A)
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if direct != 1111 { return 1; }
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fn_ptr : (Wide) -> s64 = xx accept;
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indirect := fn_ptr(w); // exercises path (B)
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if indirect != 1111 { return 2; }
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0;
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}
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