Fix CUDA int8x4 vectorize (#3928)

* Fix int8x4 vectorize

* Fix gpu shared/local memory accumulate

* Add test_shared_memory for int8x4

* Adjust test format

* Fix cpplint

src/codegen/codegen_cuda.cc

@@ -207,7 +207,11 @@ void CodeGenCUDA::PrintVecElemLoad(
     const std::string& vec, Type t, int i, std::ostream& os) {  // NOLINT(*)
   static const char access[] = {'x', 'y', 'z', 'w'};
   CHECK(i >= 0 && i < 4);
-  os << vec << "." << access[i];
+  if (t.is_int() && t.bits() == 8) {
+    os << "(0x000000ff & (" << vec << " >> " << i * 8 << "))";
+  } else {
+    os << vec << "." << access[i];
+  }
 }
 
 void CodeGenCUDA::PrintVecElemStore(
@@ -215,7 +219,12 @@ void CodeGenCUDA::PrintVecElemStore(
   this->PrintIndent();
   static const char access[] = {'x', 'y', 'z', 'w'};
   CHECK(i >= 0 && i < 4);
-  stream << vec << "." << access[i] << " = " << value << ";\n";
+  if (t.is_int() && t.bits() == 8) {
+    stream << vec << "=" << vec << " & ~(0x000000ff << " << i * 8 << ") | ("
+        << value << " << " << i * 8 << ");\n";
+  } else {
+    stream << vec << "." << access[i] << " = " << value << ";\n";
+  }
 }
 
 void CodeGenCUDA::PrintStorageSync(const Call* op) {

src/pass/verify_gpu_code.cc

@@ -83,10 +83,10 @@ class GPUCodeVerifier : public IRVisitor {
     // visit an allocation of a buffer in shared memory, record its size
     if (visited_local_buffers_.count(op->buffer_var.get()) != 0) {
       size_t size = static_cast<size_t>(op->constant_allocation_size());
-      local_memory_per_block_ += size * op->type.bytes();
+      local_memory_per_block_ += size * op->type.bytes() * op->type.lanes();
     } else if (visited_shared_buffers_.count(op->buffer_var.get()) != 0) {
       size_t size = static_cast<size_t>(op->constant_allocation_size());
-      shared_memory_per_block_ += size * op->type.bytes();
+      shared_memory_per_block_ += size * op->type.bytes() * op->type.lanes();
     }
   }
 

tests/python/unittest/test_codegen_cuda.py

@@ -52,6 +52,7 @@ def test_cuda_vectorize_add():
 
     check_cuda("float32", 64, 2)
     check_cuda("float16", 64, 2)
+    check_cuda("int8", 64, 4)
 
 
 def test_cuda_multiply_add():

tests/python/unittest/test_pass_verify_gpu_code.py

@@ -24,39 +24,45 @@ def get_verify_pass(valid, **kwargs):
     return verify_pass
 
 def test_shared_memory():
-    N = 1024
-    M = 128
-
-    A = tvm.placeholder((N,), name='A', dtype='float32')
-    B = tvm.compute((N, ), lambda i: A[i], name='B')
-
-    s = tvm.create_schedule([B.op])
-    AA = s.cache_read(A, "shared", [B])
-    o, i = s[B].split(s[B].op.axis[0], M)
-    s[AA].compute_at(s[B], o)
-    s[B].bind(o, tvm.thread_axis("blockIdx.x"))
-    s[B].bind(i, tvm.thread_axis("threadIdx.x"))
-
-    # shared memory usage: M * 4B
-    # thread usage: M
-
-    for target in ['opencl', 'cuda']:
-        if not tvm.context(target).exist:
-            continue
-        valid = [None]
-        with tvm.build_config(**{"add_lower_pass": [
-            (2, get_verify_pass(valid,
-                                max_shared_memory_per_block=4 * M - 1,
-                                max_threads_per_block=M))]}):
-            tvm.build(s, [A, B], target)
-        assert not valid[0]
-
-        with tvm.build_config(**{"add_lower_pass": [
-            (2, get_verify_pass(valid,
-                                max_shared_memory_per_block=4 * M,
-                                max_threads_per_block=M))]}):
-            tvm.build(s, [A, B], target)
-        assert valid[0]
+    def check_shared_memory(dtype):
+        N = 1024
+        M = 128
+
+        tvm_type = tvm.datatype._TVMType(dtype)
+        type_size = tvm_type.bits // 8 * tvm_type.lanes
+
+        A = tvm.placeholder((N,), name='A', dtype=dtype)
+        B = tvm.compute((N, ), lambda i: A[i], name='B')
+
+        s = tvm.create_schedule([B.op])
+        AA = s.cache_read(A, "shared", [B])
+        o, i = s[B].split(s[B].op.axis[0], M)
+        s[AA].compute_at(s[B], o)
+        s[B].bind(o, tvm.thread_axis("blockIdx.x"))
+        s[B].bind(i, tvm.thread_axis("threadIdx.x"))
+
+        # shared memory usage: M * sizeof(dtype) Bytes
+        # thread usage: M
+
+        for target in ['opencl', 'cuda']:
+            if not tvm.context(target).exist:
+                continue
+            valid = [None]
+            with tvm.build_config(**{"add_lower_pass": [
+                (2, get_verify_pass(valid,
+                                    max_shared_memory_per_block=type_size * M - 1,
+                                    max_threads_per_block=M))]}):
+                tvm.build(s, [A, B], target)
+            assert not valid[0]
+
+            with tvm.build_config(**{"add_lower_pass": [
+                (2, get_verify_pass(valid,
+                                    max_shared_memory_per_block=type_size * M,
+                                    max_threads_per_block=M))]}):
+                tvm.build(s, [A, B], target)
+            assert valid[0]
+    check_shared_memory('float32')
+    check_shared_memory('int8x4')
 
 def test_local_memory():
     N = 1024