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wasm: splat for vector elements divisible by 8

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This implements `@splat` for vectors where the element type is
divisible by 8 and a power of two. This is fairly simple as we can
store the values directly within the virtual stack. But for
all other sizes, we must first shift and bitwise-or the values
before we can store them to fit them like a packed-struct, rather
than an array.
This commit is contained in:
Luuk de Gram 2022-12-11 15:18:33 +01:00
parent c6d654f73b
commit 355b5929b2
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GPG Key ID: A8CFE58E4DC7D664
1 changed files with 17 additions and 2 deletions
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19
src/arch/wasm/CodeGen.zig
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@ -4433,7 +4433,6 @@ fn airSplat(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
const ty = func.air.typeOfIndex(inst);
const elem_ty = ty.childType();
const result = try func.allocLocal(ty);
if (determineSimdStoreStrategy(ty, func.target) == .direct) blk: {
switch (operand) {
// when the operand lives in the linear memory section, we can directly
@ -4447,6 +4446,7 @@ fn airSplat(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
64 => std.wasm.simdOpcode(.v128_load64_splat),
else => break :blk, // Cannot make use of simd-instructions
};
const result = try func.allocLocal(ty);
try func.emitWValue(operand);
// TODO: Add helper functions for simd opcodes
const extra_index = @intCast(u32, func.mir_extra.items.len);
@ -4468,6 +4468,7 @@ fn airSplat(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
64 => if (elem_ty.isInt()) std.wasm.simdOpcode(.i64x2_splat) else std.wasm.simdOpcode(.f64x2_splat),
else => break :blk, // Cannot make use of simd-instructions
};
const result = try func.allocLocal(ty);
try func.emitWValue(operand);
const extra_index = @intCast(u32, func.mir_extra.items.len);
try func.mir_extra.append(func.gpa, opcode);
@ -4478,8 +4479,22 @@ fn airSplat(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
else => unreachable,
}
}
const elem_size = elem_ty.bitSize(func.target);
const vector_len = @intCast(usize, ty.vectorLen());
if ((!std.math.isPowerOfTwo(elem_size) or elem_size % 8 != 0) and vector_len > 1) {
return func.fail("TODO: WebAssembly `@splat` for arbitrary element bitsize {d}", .{elem_size});
}
return func.fail("TODO: Implement wasm airSplat unrolled", .{});
const result = try func.allocStack(ty);
const elem_byte_size = @intCast(u32, elem_ty.abiSize(func.target));
var index: usize = 0;
var offset: u32 = 0;
while (index < vector_len) : (index += 1) {
try func.store(result, operand, elem_ty, offset);
offset += elem_byte_size;
}
return func.finishAir(inst, result, &.{ty_op.operand});
}
fn airSelect(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {