guan404ming commented on code in PR #20167:
URL: https://github.com/apache/tvm/pull/20167#discussion_r3849753101
##########
web/emcc/wasm_runtime.cc:
##########
@@ -126,38 +128,93 @@ TVM_FFI_STATIC_INIT_BLOCK() {
});
}
+size_t GetCheckedTensorElementCount(const Tensor& tensor) {
+ size_t size = 1;
+ for (int i = 0; i < tensor->ndim; ++i) {
+ TVM_FFI_ICHECK_GE(tensor->shape[i], 0);
+ const uint64_t dim_u64 = static_cast<uint64_t>(tensor->shape[i]);
+ TVM_FFI_ICHECK_LE(dim_u64, std::numeric_limits<size_t>::max());
+ const size_t dim = static_cast<size_t>(dim_u64);
+ if (size != 0) {
+ TVM_FFI_ICHECK_LE(dim, std::numeric_limits<size_t>::max() / size);
+ }
+ size *= dim;
+ }
+ return size;
+}
+
+void CheckF32CPUTensor(const Tensor& tensor) {
+ TVM_FFI_ICHECK_EQ(tensor->device.device_type, kDLCPU);
+ TVM_FFI_ICHECK(tensor.IsContiguous());
+ TVM_FFI_ICHECK_EQ(tensor->dtype.code, kDLFloat);
+ TVM_FFI_ICHECK_EQ(tensor->dtype.bits, 32);
+ TVM_FFI_ICHECK_EQ(tensor->dtype.lanes, 1);
+}
+
void ArrayDecodeStorage(Tensor cpu_arr, TVMFFIByteArray* bytes, const
std::string& format,
const std::string& dtype) {
TVM_FFI_ICHECK_NE(bytes, nullptr);
const char* byte_data = bytes->data;
const size_t byte_size = bytes->size;
if (format == "f32-to-bf16" && dtype == "float32") {
- const uint16_t* bf16 = reinterpret_cast<const uint16_t*>(byte_data);
- uint32_t* data = static_cast<uint32_t*>(cpu_arr->data);
- TVM_FFI_ICHECK(cpu_arr.IsContiguous());
- size_t size = 1;
- for (int i = 0; i < cpu_arr->ndim; ++i) {
- size *= cpu_arr->shape[i];
+ CheckF32CPUTensor(cpu_arr);
+ const size_t size = GetCheckedTensorElementCount(cpu_arr);
+ TVM_FFI_ICHECK_LE(size, std::numeric_limits<size_t>::max() / 4);
+ TVM_FFI_ICHECK_EQ(byte_size, size * 2);
+ if (size == 0) {
+ return;
}
- TVM_FFI_ICHECK_EQ(size, byte_size / 2);
+ TVM_FFI_ICHECK_NE(cpu_arr->data, nullptr);
+ TVM_FFI_ICHECK_NE(byte_data, nullptr);
+ const uint8_t* bf16 = reinterpret_cast<const uint8_t*>(byte_data);
+ uint8_t* data = static_cast<uint8_t*>(cpu_arr->data) +
cpu_arr->byte_offset;
for (size_t i = 0; i < size; ++i) {
- data[i] = static_cast<uint32_t>(bf16[i]) << 16;
+ data[4 * i] = 0;
+ data[4 * i + 1] = 0;
+ data[4 * i + 2] = bf16[2 * i];
+ data[4 * i + 3] = bf16[2 * i + 1];
}
} else {
cpu_arr.CopyFromBytes(byte_data, byte_size);
}
}
+void ArrayDecodeBF16ToF32Inplace(Tensor cpu_arr, int64_t encoded_nbytes) {
+ CheckF32CPUTensor(cpu_arr);
+ TVM_FFI_ICHECK_GE(encoded_nbytes, 0);
+
+ const size_t size = GetCheckedTensorElementCount(cpu_arr);
+ TVM_FFI_ICHECK_LE(size, std::numeric_limits<size_t>::max() / 4);
+ TVM_FFI_ICHECK_EQ(static_cast<uint64_t>(encoded_nbytes),
static_cast<uint64_t>(size) * 2);
+ if (size == 0) {
+ return;
+ }
+ TVM_FFI_ICHECK_NE(cpu_arr->data, nullptr);
+
+ uint8_t* data = static_cast<uint8_t*>(cpu_arr->data) + cpu_arr->byte_offset;
+ for (size_t i = size; i != 0; --i) {
Review Comment:
I think this would be a bit faster if we wrote each element as one 32-bit
value (e.g. via `memcpy` of a `uint32_t`) instead of four separate byte stores,
since this loop runs over every BF16 parameter.
##########
web/emcc/wasm_runtime.cc:
##########
@@ -126,38 +128,93 @@ TVM_FFI_STATIC_INIT_BLOCK() {
});
}
+size_t GetCheckedTensorElementCount(const Tensor& tensor) {
Review Comment:
I think a plain product over `shape` would be enough here; tensor shapes are
already validated at allocation time, so the overflow checks feel a little
heavier than needed.
##########
web/src/runtime.ts:
##########
@@ -1373,6 +1417,24 @@ export class Instance implements Disposable {
}
}
+ /** Return the exact byte size of a packed BF16 tensor. */
+ private getPackedBF16Bytes(shape: Array<number>): number {
Review Comment:
I think we could drop this helper, since `ArrayDecodeBF16ToF32Inplace`
already rejects a size mismatch via `TVM_FFI_ICHECK_EQ`. Keeping the check in
one place would be a bit simpler to maintain.
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