commit 821f1a8a604dbbfe2b1c487c5695952d994a9460
author Antonio Maiorano <amaiorano@google.com> Thu Oct 21 20:56:34 2021 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Oct 21 20:56:34 2021 +0000
tree e85514c9e2c0013830746e0c9d101b693f8afb66
parent 1d553062552b08fd132011fda5a8aa4e5bd0257c

dawn_node: add "dawn-backend=<value>" flag

As an alternative to setting the "DAWNNODE_BACKEND" env var.

Bug: dawn:1163
Change-Id: I33ace14e7603b97caf7286a109a31160853f62e0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/66961
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

src/dawn_node/binding/GPU.cpp

diff --git a/src/dawn_node/binding/GPU.cpp b/src/dawn_node/binding/GPU.cpp
index 52b5f9c..e6e03c4 100644
--- a/src/dawn_node/binding/GPU.cpp
+++ b/src/dawn_node/binding/GPU.cpp
@@ -19,7 +19,7 @@
 #include <cstdlib>
 
 namespace {
-    std::string getEnvVar(const char* varName) {
+    std::string GetEnvVar(const char* varName) {
 #if defined(_WIN32)
         // Use _dupenv_s to avoid unsafe warnings about std::getenv
         char* value = nullptr;
@@ -81,27 +81,39 @@
 #endif
 
         auto targetBackendType = defaultBackendType;
+        std::string forceBackend;
 
         // Check for override from env var
-        std::string envVar = getEnvVar("DAWNNODE_BACKEND");
-        std::transform(envVar.begin(), envVar.end(), envVar.begin(),
+        if (std::string envVar = GetEnvVar("DAWNNODE_BACKEND"); !envVar.empty()) {
+            forceBackend = envVar;
+        }
+
+        // Check for override from flag
+        if (auto f = flags_.Get("dawn-backend")) {
+            forceBackend = *f;
+        }
+
+        std::transform(forceBackend.begin(), forceBackend.end(), forceBackend.begin(),
                        [](char c) { return std::tolower(c); });
-        if (envVar == "null") {
-            targetBackendType = wgpu::BackendType::Null;
-        } else if (envVar == "webgpu") {
-            targetBackendType = wgpu::BackendType::WebGPU;
-        } else if (envVar == "d3d11") {
-            targetBackendType = wgpu::BackendType::D3D11;
-        } else if (envVar == "d3d12" || envVar == "d3d") {
-            targetBackendType = wgpu::BackendType::D3D12;
-        } else if (envVar == "metal") {
-            targetBackendType = wgpu::BackendType::Metal;
-        } else if (envVar == "vulkan" || envVar == "vk") {
-            targetBackendType = wgpu::BackendType::Vulkan;
-        } else if (envVar == "opengl" || envVar == "gl") {
-            targetBackendType = wgpu::BackendType::OpenGL;
-        } else if (envVar == "opengles" || envVar == "gles") {
-            targetBackendType = wgpu::BackendType::OpenGLES;
+
+        if (!forceBackend.empty()) {
+            if (forceBackend == "null") {
+                targetBackendType = wgpu::BackendType::Null;
+            } else if (forceBackend == "webgpu") {
+                targetBackendType = wgpu::BackendType::WebGPU;
+            } else if (forceBackend == "d3d11") {
+                targetBackendType = wgpu::BackendType::D3D11;
+            } else if (forceBackend == "d3d12" || forceBackend == "d3d") {
+                targetBackendType = wgpu::BackendType::D3D12;
+            } else if (forceBackend == "metal") {
+                targetBackendType = wgpu::BackendType::Metal;
+            } else if (forceBackend == "vulkan" || forceBackend == "vk") {
+                targetBackendType = wgpu::BackendType::Vulkan;
+            } else if (forceBackend == "opengl" || forceBackend == "gl") {
+                targetBackendType = wgpu::BackendType::OpenGL;
+            } else if (forceBackend == "opengles" || forceBackend == "gles") {
+                targetBackendType = wgpu::BackendType::OpenGLES;
+            }
         }
 
         // Default to first adapter if we don't find a match