added support for rocm gpu autodetect (#549)

* added support for rocm gpu autodetect

* changed type casting from old style to static_cast

* fixed code to generate gfx specific code object

* fixed namespaces

HalideIR @ cb3c025d

-Subproject commit a40a3e2fedee88d2f7b97ba4caf8a9d0eb25886f
+Subproject commit cb3c025d5b91ab994b063a85bc935fc364d8f491

src/codegen/llvm/codegen_amdgpu.cc

@@ -135,9 +135,21 @@ runtime::Module BuildAMDGPU(Array<LoweredFunc> funcs, std::string target) {
   CHECK(target.length(
 ) >= 4 &&
         target.substr(0, 4) == "rocm");
+
+  TVMContext tvmCtx;
+  tvmCtx.device_type = kROCM;
+  tvmCtx.device_id = 0;
+  TVMRetValue val;
+  tvm::runtime::DeviceAPI::Get(tvmCtx)->GetAttr(tvmCtx, tvm::runtime::kExist, &val);
+  if (val.operator int() == 1) {
+    tvm::runtime::DeviceAPI::Get(tvmCtx)->GetAttr(tvmCtx, tvm::runtime::kComputeVersion, &val);
+  } else {
+    val = 803;
+  }
+
   llvm::TargetMachine* tm = \
-    GetLLVMTargetMachine("-mtriple=amdgcn-amd-amdhsa-hcc -mcpu=gfx803" + \
-    target.substr(4, target.length() - 4));
+    GetLLVMTargetMachine("-mtriple=amdgcn-amd-amdhsa-hcc -mcpu=gfx" + \
+    std::to_string(val.operator int())+ target.substr(4, target.length() - 4));
 
   std::unique_ptr<CodeGenAMDGPU> cg(new CodeGenAMDGPU());
   std::unique_ptr<llvm::LLVMContext> ctx(new llvm::LLVMContext());

src/runtime/rocm/rocm_device_api.cc

@@ -44,7 +44,11 @@ class ROCMDeviceAPI final : public DeviceAPI {
         value = 64;
         break;
       }
-      case kComputeVersion: return;
+      case kComputeVersion:
+        hipDeviceProp_t prop;
+        ROCM_CALL(hipGetDeviceProperties(&prop, ctx.device_id));
+        *rv = prop.gcnArch;
+        return;
     }
     *rv = value;
   }