Add Dockerfile for building and running local Skia checkout with SwiftShader

This also adds a little helper to fuzz that allows us to see what
GPU is being targeted.

This is the first step in getting a SwiftShader fuzz target.

To prove that this works, simply download this patch and run:

./docker/skia-with-swift-shader-base/build-with-swift-shader-and-run "out/with-swift-shader/fuzz --gpuInfo -t api -n NativeGLCanvas -b out/with-swift-shader/fiddle"
Running supplied command ['out/with-swift-shader/fuzz', '--gpuInfo', '-t', 'api', '-n', 'NativeGLCanvas', '-b', 'out/with-swift-shader/fiddle']
Fuzzing NativeGLCanvas...
GL_RENDERER Google SwiftShader
GL_VENDOR Google Inc.
GL_VERSION OpenGL ES 3.0 SwiftShader 4.0.0.6

Bug: skia:
Change-Id: I3cc11a6bcd14f70f6025011722f9a73c94cb1f65
Reviewed-on: https://skia-review.googlesource.com/132269
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>

3 files changed, 31 insertions, 0 deletions

diff --git a/fuzz/FuzzCanvas.cpp b/fuzz/FuzzCanvas.cpp
index 5c92fd1eb5..b66e5187dd 100644
--- a/fuzz/FuzzCanvas.cpp
+++ b/fuzz/FuzzCanvas.cpp
@@ -1811,12 +1811,17 @@ static void fuzz_ganesh(Fuzz* fuzz, GrContext* context) {
     fuzz_canvas(fuzz, surface->getCanvas());
 }
 
+extern bool FLAGS_gpuInfo;
+
 DEF_FUZZ(NativeGLCanvas, fuzz) {
     sk_gpu_test::GrContextFactory f;
     GrContext* context = f.get(sk_gpu_test::GrContextFactory::kGL_ContextType);
     if (!context) {
         context = f.get(sk_gpu_test::GrContextFactory::kGLES_ContextType);
     }
+    if (FLAGS_gpuInfo) {
+        dumpGPUInfo(context);
+    }
     fuzz_ganesh(fuzz, context);
 }
 
diff --git a/fuzz/FuzzCommon.h b/fuzz/FuzzCommon.h
index 7615fe723e..9435b43552 100644
--- a/fuzz/FuzzCommon.h
+++ b/fuzz/FuzzCommon.h
@@ -12,6 +12,30 @@
 #include "SkPath.h"
 #include "SkRegion.h"
 
+
+#if SK_SUPPORT_GPU
+#include "GrContextFactory.h"
+#include "gl/GrGLFunctions.h"
+#include "gl/GrGLGpu.h"
+#include "gl/GrGLUtil.h"
+#include "GrContextPriv.h"
+
+inline void dumpGPUInfo(GrContext* context) {
+    const GrGLInterface* gl = static_cast<GrGLGpu*>(context->contextPriv().getGpu())
+                                    ->glInterface();
+    const GrGLubyte* output;
+    GR_GL_CALL_RET(gl, output, GetString(GR_GL_RENDERER));
+    SkDebugf("GL_RENDERER %s\n", (const char*) output);
+
+    GR_GL_CALL_RET(gl, output, GetString(GR_GL_VENDOR));
+    SkDebugf("GL_VENDOR %s\n", (const char*) output);
+
+    GR_GL_CALL_RET(gl, output, GetString(GR_GL_VERSION));
+    SkDebugf("GL_VERSION %s\n", (const char*) output);
+}
+
+#endif
+
 // We don't always want to test NaNs and infinities.
 static inline void fuzz_nice_float(Fuzz* fuzz, float* f) {
     float v;
@@ -60,3 +84,4 @@ void FuzzPath(Fuzz* fuzz, SkPath* path, int maxOps);
 void BuildPath(Fuzz* fuzz, SkPath* path, int last_verb);
 
 #endif
+
diff --git a/fuzz/fuzz.cpp b/fuzz/fuzz.cpp
index 0917747790..7bf03f1adf 100644
--- a/fuzz/fuzz.cpp
+++ b/fuzz/fuzz.cpp
@@ -46,6 +46,7 @@ DEFINE_string2(bytes, b, "", "A path to a file or a directory. If a file, the "
 DEFINE_string2(name, n, "", "If --type is 'api', fuzz the API with this name.");
 DEFINE_string2(dump, d, "", "If not empty, dump 'image*' or 'skp' types as a "
         "PNG with this name.");
+DEFINE_bool2(gpuInfo, g, false, "Display GPU information on relevant targets.");
 DEFINE_bool2(verbose, v, false, "Print more information while fuzzing.");
 DEFINE_string2(type, t, "", "How to interpret --bytes, one of:\n"
                             "animated_image_decode\n"