tiny.choir.backends.wasm.emission.function.instruction.cast

1const std = @import("std");2const ir = @import("../../../../../core/root.zig");3const dialects = @import("../../../../../dialects/root.zig");4const emission = @import("../../root.zig");5const instruction = @import("root.zig");67const ScalarKind = dialects.arith.ScalarKind;89pub fn write(10    comptime Out: type,11    writer: *instruction.Writer(Out),12    operation: *ir.Operation,13    bitcast: bool,14) emission.Error!void {15    const operand = operation.getOperand(0) orelse return error.CodeGenFailed;16    const result = operation.getResult(0) orelse return error.CodeGenFailed;17    const source = emission.types.scalarKindForType(operand.type) orelse18        return error.CodeGenFailed;19    const target = emission.types.scalarKindForType(result.type) orelse20        return error.CodeGenFailed;21    try writer.writeValue(operand);22    if (!scalarCastIsWasmNoop(source, target)) {23        const opcode = if (bitcast)24            try bitcastOpcode(source, target)25        else26            try castOpcode(source, target);27        try writer.out.writeByte(opcode);28    }29    try writer.writeLocalSet(try writer.localFor(result));30}3132fn bitcastOpcode(source: ScalarKind, target: ScalarKind) error{CodeGenFailed}!u8 {33    return switch (source) {34        .i32, .u32, .index, .bool => switch (target) {35            .f32 => 0xbe,36            else => error.CodeGenFailed,37        },38        .i64, .u64 => switch (target) {39            .f64 => 0xbf,40            else => error.CodeGenFailed,41        },42        .f32 => switch (target) {43            .i32, .u32, .index => 0xbc,44            else => error.CodeGenFailed,45        },46        .f64 => switch (target) {47            .i64, .u64 => 0xbd,48            else => error.CodeGenFailed,49        },50        else => error.CodeGenFailed,51    };52}5354fn castOpcode(source: ScalarKind, target: ScalarKind) error{CodeGenFailed}!u8 {55    return switch (source) {56        .i32, .index, .bool => switch (target) {57            .i64 => 0xac,58            .u64 => 0xad,59            .f32 => 0xb2,60            .f64 => 0xb7,61            else => error.CodeGenFailed,62        },63        .u32 => switch (target) {64            .i64, .u64 => 0xad,65            .f32 => 0xb3,66            .f64 => 0xb8,67            else => error.CodeGenFailed,68        },69        .i64 => switch (target) {70            .i32, .u32, .index => 0xa7,71            .f32 => 0xb4,72            .f64 => 0xb9,73            else => error.CodeGenFailed,74        },75        .u64 => switch (target) {76            .i32, .u32, .index => 0xa7,77            .f32 => 0xb5,78            .f64 => 0xba,79            else => error.CodeGenFailed,80        },81        .f32 => switch (target) {82            .f64 => 0xbb,83            else => error.CodeGenFailed,84        },85        .f64 => switch (target) {86            .f32 => 0xb6,87            else => error.CodeGenFailed,88        },89        else => error.CodeGenFailed,90    };91}9293fn scalarCastIsWasmNoop(source: ScalarKind, target: ScalarKind) bool {94    if (source == target) return true;95    return switch (source) {96        .i32, .u32, .index, .bool => switch (target) {97            .i32, .u32, .index => true,98            else => false,99        },100        .i64, .u64 => switch (target) {101            .i64, .u64 => true,102            else => false,103        },104        else => false,105    };106}107108test "wasm integer representation casts preserve exact no-op rules" {109    try std.testing.expect(scalarCastIsWasmNoop(.index, .u32));110    try std.testing.expect(scalarCastIsWasmNoop(.u32, .i32));111    try std.testing.expect(scalarCastIsWasmNoop(.i64, .u64));112    try std.testing.expect(scalarCastIsWasmNoop(.bool, .i32));113    try std.testing.expect(!scalarCastIsWasmNoop(.i32, .bool));114    try std.testing.expect(!scalarCastIsWasmNoop(.i32, .i64));115    try std.testing.expect(!scalarCastIsWasmNoop(.f32, .i32));116}

1pub const cast = @import("cast.zig");