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https://github.com/ghostty-org/ghostty.git
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00dfd67bee
The previous runtime_detect.zig called std.zig.system.resolveTargetQuery which pulled in the entire Zig target/CPU model table infrastructure for every architecture (~4,000 symbols, ~175 KB of data tables, ~130 KB of code). This bloated the binary by ~500 KB and shifted code layout enough to cause a measurable icache/branch-predictor regression in unrelated hot paths like the terminal parser (~20% more cycles for identical instruction counts). Replace with minimal, direct CPU feature detection per architecture: CPUID + XGETBV inline assembly on x86, sysctlbyname on Darwin AArch64, and getauxval/prctl via std.os.linux (direct syscalls, no libc) on Linux for AArch64, PPC, S390x, RISC-V, and LoongArch. Split into per-architecture files under src/detect/ for maintainability.
50 lines
1.8 KiB
Zig
50 lines
1.8 KiB
Zig
const builtin = @import("builtin");
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const HwyTargets = @import("targets.zig").Targets;
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const x86 = @import("detect/x86.zig");
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const aarch64_darwin = @import("detect/aarch64_darwin.zig");
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const aarch64_linux = @import("detect/aarch64_linux.zig");
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const ppc = @import("detect/ppc.zig");
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const s390x = @import("detect/s390x.zig");
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const riscv = @import("detect/riscv.zig");
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const loongarch = @import("detect/loongarch.zig");
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/// Detect Highway targets at runtime using minimal, direct CPU feature
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/// probing.
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///
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/// Previous versions called std.zig.system.resolveTargetQuery which
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/// drags in the full Zig target/CPU model tables for every architecture,
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/// bloating the binary by ~300 KB and causing code-layout regressions in
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/// unrelated hot paths (icache / branch-predictor pressure).
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///
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/// This version uses only inline assembly (CPUID on x86, MRS on AArch64)
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/// and lightweight syscalls (sysctlbyname on Darwin, getauxval on Linux),
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/// so it adds no data tables and no std.Target dependency.
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pub export fn ghostty_hwy_detect_targets() callconv(.c) i64 {
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return switch (builtin.cpu.arch) {
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.x86_64, .x86 => x86.detect(),
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.aarch64, .aarch64_be => detectAarch64(),
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.powerpc, .powerpc64, .powerpc64le => ppc.detect(),
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.s390x => s390x.detect(),
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.riscv32, .riscv64 => riscv.detect(),
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.loongarch32, .loongarch64 => loongarch.detect(),
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else => 0,
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};
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}
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fn detectAarch64() i64 {
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var t: HwyTargets = .{};
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// All AArch64 implementations have NEON.
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t.neon_without_aes = true;
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if (comptime builtin.os.tag.isDarwin()) {
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return aarch64_darwin.detect(&t);
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} else if (comptime builtin.os.tag == .linux) {
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return aarch64_linux.detect(&t);
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}
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// Other OS: return baseline NEON.
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return @bitCast(t);
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}
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