zig/lib/compiler_rt/common.zig
2024-10-15 19:29:56 +02:00

269 lines
10 KiB
Zig

const std = @import("std");
const builtin = @import("builtin");
const native_endian = builtin.cpu.arch.endian();
const ofmt_c = builtin.object_format == .c;
pub const linkage: std.builtin.GlobalLinkage = if (builtin.is_test)
.internal
else if (ofmt_c)
.strong
else
.weak;
/// Determines the symbol's visibility to other objects.
/// For WebAssembly this allows the symbol to be resolved to other modules, but will not
/// export it to the host runtime.
pub const visibility: std.builtin.SymbolVisibility =
if (builtin.target.isWasm() and linkage != .internal) .hidden else .default;
pub const want_aeabi = switch (builtin.abi) {
.eabi,
.eabihf,
.musleabi,
.musleabihf,
.gnueabi,
.gnueabihf,
.android,
.androideabi,
=> switch (builtin.cpu.arch) {
.arm, .armeb, .thumb, .thumbeb => true,
else => false,
},
else => false,
};
pub const want_mingw_arm_abi = builtin.cpu.arch.isArmOrThumb() and builtin.target.isMinGW();
pub const want_ppc_abi = builtin.cpu.arch.isPowerPC();
pub const want_float_exceptions = !builtin.cpu.arch.isWasm();
// Libcalls that involve u128 on Windows x86-64 are expected by LLVM to use the
// calling convention of @Vector(2, u64), rather than what's standard.
pub const want_windows_v2u64_abi = builtin.os.tag == .windows and builtin.cpu.arch == .x86_64 and !ofmt_c;
/// This governs whether to use these symbol names for f16/f32 conversions
/// rather than the standard names:
/// * __gnu_f2h_ieee
/// * __gnu_h2f_ieee
/// Known correct configurations:
/// x86_64-freestanding-none => true
/// x86_64-linux-none => true
/// x86_64-linux-gnu => true
/// x86_64-linux-musl => true
/// x86_64-linux-eabi => true
/// arm-linux-musleabihf => true
/// arm-linux-gnueabihf => true
/// arm-linux-eabihf => false
/// wasm32-wasi-musl => false
/// wasm32-freestanding-none => false
/// x86_64-windows-gnu => true
/// x86_64-windows-msvc => true
/// any-macos-any => false
pub const gnu_f16_abi = switch (builtin.cpu.arch) {
.wasm32,
.wasm64,
.riscv64,
.riscv32,
=> false,
.x86, .x86_64 => true,
.arm, .armeb, .thumb, .thumbeb => switch (builtin.abi) {
.eabi, .eabihf => false,
else => true,
},
else => !builtin.os.tag.isDarwin(),
};
pub const want_sparc_abi = builtin.cpu.arch.isSPARC();
// Avoid dragging in the runtime safety mechanisms into this .o file, unless
// we're trying to test compiler-rt.
pub const Panic = if (builtin.is_test) std.debug.FormattedPanic else struct {};
/// To be deleted after zig1.wasm is updated.
pub fn panic(msg: []const u8, error_return_trace: ?*std.builtin.StackTrace, ret_addr: ?usize) noreturn {
if (builtin.is_test) {
std.debug.defaultPanic(msg, error_return_trace, ret_addr orelse @returnAddress());
} else {
unreachable;
}
}
/// AArch64 is the only ABI (at the moment) to support f16 arguments without the
/// need for extending them to wider fp types.
/// TODO remove this; do this type selection in the language rather than
/// here in compiler-rt.
pub fn F16T(comptime OtherType: type) type {
return switch (builtin.cpu.arch) {
.arm, .armeb, .thumb, .thumbeb => if (std.Target.arm.featureSetHas(builtin.cpu.features, .has_v8))
switch (builtin.abi.floatAbi()) {
.soft => u16,
.hard => f16,
}
else
u16,
.aarch64, .aarch64_be => f16,
.riscv32, .riscv64 => f16,
.x86, .x86_64 => if (builtin.target.isDarwin()) switch (OtherType) {
// Starting with LLVM 16, Darwin uses different abi for f16
// depending on the type of the other return/argument..???
f32, f64 => u16,
f80, f128 => f16,
else => unreachable,
} else f16,
else => u16,
};
}
pub fn wideMultiply(comptime Z: type, a: Z, b: Z, hi: *Z, lo: *Z) void {
switch (Z) {
u16 => {
// 16x16 --> 32 bit multiply
const product = @as(u32, a) * @as(u32, b);
hi.* = @intCast(product >> 16);
lo.* = @truncate(product);
},
u32 => {
// 32x32 --> 64 bit multiply
const product = @as(u64, a) * @as(u64, b);
hi.* = @truncate(product >> 32);
lo.* = @truncate(product);
},
u64 => {
const S = struct {
fn loWord(x: u64) u64 {
return @as(u32, @truncate(x));
}
fn hiWord(x: u64) u64 {
return @as(u32, @truncate(x >> 32));
}
};
// 64x64 -> 128 wide multiply for platforms that don't have such an operation;
// many 64-bit platforms have this operation, but they tend to have hardware
// floating-point, so we don't bother with a special case for them here.
// Each of the component 32x32 -> 64 products
const plolo: u64 = S.loWord(a) * S.loWord(b);
const plohi: u64 = S.loWord(a) * S.hiWord(b);
const philo: u64 = S.hiWord(a) * S.loWord(b);
const phihi: u64 = S.hiWord(a) * S.hiWord(b);
// Sum terms that contribute to lo in a way that allows us to get the carry
const r0: u64 = S.loWord(plolo);
const r1: u64 = S.hiWord(plolo) +% S.loWord(plohi) +% S.loWord(philo);
lo.* = r0 +% (r1 << 32);
// Sum terms contributing to hi with the carry from lo
hi.* = S.hiWord(plohi) +% S.hiWord(philo) +% S.hiWord(r1) +% phihi;
},
u128 => {
const Word_LoMask: u64 = 0x00000000ffffffff;
const Word_HiMask: u64 = 0xffffffff00000000;
const Word_FullMask: u64 = 0xffffffffffffffff;
const S = struct {
fn Word_1(x: u128) u64 {
return @as(u32, @truncate(x >> 96));
}
fn Word_2(x: u128) u64 {
return @as(u32, @truncate(x >> 64));
}
fn Word_3(x: u128) u64 {
return @as(u32, @truncate(x >> 32));
}
fn Word_4(x: u128) u64 {
return @as(u32, @truncate(x));
}
};
// 128x128 -> 256 wide multiply for platforms that don't have such an operation;
// many 64-bit platforms have this operation, but they tend to have hardware
// floating-point, so we don't bother with a special case for them here.
const product11: u64 = S.Word_1(a) * S.Word_1(b);
const product12: u64 = S.Word_1(a) * S.Word_2(b);
const product13: u64 = S.Word_1(a) * S.Word_3(b);
const product14: u64 = S.Word_1(a) * S.Word_4(b);
const product21: u64 = S.Word_2(a) * S.Word_1(b);
const product22: u64 = S.Word_2(a) * S.Word_2(b);
const product23: u64 = S.Word_2(a) * S.Word_3(b);
const product24: u64 = S.Word_2(a) * S.Word_4(b);
const product31: u64 = S.Word_3(a) * S.Word_1(b);
const product32: u64 = S.Word_3(a) * S.Word_2(b);
const product33: u64 = S.Word_3(a) * S.Word_3(b);
const product34: u64 = S.Word_3(a) * S.Word_4(b);
const product41: u64 = S.Word_4(a) * S.Word_1(b);
const product42: u64 = S.Word_4(a) * S.Word_2(b);
const product43: u64 = S.Word_4(a) * S.Word_3(b);
const product44: u64 = S.Word_4(a) * S.Word_4(b);
const sum0: u128 = @as(u128, product44);
const sum1: u128 = @as(u128, product34) +%
@as(u128, product43);
const sum2: u128 = @as(u128, product24) +%
@as(u128, product33) +%
@as(u128, product42);
const sum3: u128 = @as(u128, product14) +%
@as(u128, product23) +%
@as(u128, product32) +%
@as(u128, product41);
const sum4: u128 = @as(u128, product13) +%
@as(u128, product22) +%
@as(u128, product31);
const sum5: u128 = @as(u128, product12) +%
@as(u128, product21);
const sum6: u128 = @as(u128, product11);
const r0: u128 = (sum0 & Word_FullMask) +%
((sum1 & Word_LoMask) << 32);
const r1: u128 = (sum0 >> 64) +%
((sum1 >> 32) & Word_FullMask) +%
(sum2 & Word_FullMask) +%
((sum3 << 32) & Word_HiMask);
lo.* = r0 +% (r1 << 64);
hi.* = (r1 >> 64) +%
(sum1 >> 96) +%
(sum2 >> 64) +%
(sum3 >> 32) +%
sum4 +%
(sum5 << 32) +%
(sum6 << 64);
},
else => @compileError("unsupported"),
}
}
pub fn normalize(comptime T: type, significand: *std.meta.Int(.unsigned, @typeInfo(T).float.bits)) i32 {
const Z = std.meta.Int(.unsigned, @typeInfo(T).float.bits);
const integerBit = @as(Z, 1) << std.math.floatFractionalBits(T);
const shift = @clz(significand.*) - @clz(integerBit);
significand.* <<= @as(std.math.Log2Int(Z), @intCast(shift));
return @as(i32, 1) - shift;
}
pub inline fn fneg(a: anytype) @TypeOf(a) {
const F = @TypeOf(a);
const bits = @typeInfo(F).float.bits;
const U = @Type(.{ .int = .{
.signedness = .unsigned,
.bits = bits,
} });
const sign_bit_mask = @as(U, 1) << (bits - 1);
const negated = @as(U, @bitCast(a)) ^ sign_bit_mask;
return @bitCast(negated);
}
/// Allows to access underlying bits as two equally sized lower and higher
/// signed or unsigned integers.
pub fn HalveInt(comptime T: type, comptime signed_half: bool) type {
return extern union {
pub const bits = @divExact(@typeInfo(T).int.bits, 2);
pub const HalfTU = std.meta.Int(.unsigned, bits);
pub const HalfTS = std.meta.Int(.signed, bits);
pub const HalfT = if (signed_half) HalfTS else HalfTU;
all: T,
s: if (native_endian == .little)
extern struct { low: HalfT, high: HalfT }
else
extern struct { high: HalfT, low: HalfT },
};
}