wasm: Add compile target option when creating slang session (#5403)

* wasm: Add compile target option when creating slang session

Also add a new interface to return spirv code which is binary,

because 'std::string ComponentType::getEntryPointCode' is not
suitable for returning the binary data.

We use a more standard way that wrap the binary data by using
emscripten::val as the return type.

* Add target of metal

3 files changed, 91 insertions, 4 deletions

diff --git a/source/slang-wasm/slang-wasm-bindings.cpp b/source/slang-wasm/slang-wasm-bindings.cpp
index f8175180a..d033f3846 100644
--- a/source/slang-wasm/slang-wasm-bindings.cpp
+++ b/source/slang-wasm/slang-wasm-bindings.cpp
@@ -17,6 +17,11 @@ EMSCRIPTEN_BINDINGS(slang)
         "getLastError",
         &slang::wgsl::getLastError);
 
+    function(
+        "getCompileTargets",
+        &slang::wgsl::getCompileTargets,
+        return_value_policy::take_ownership());
+
     class_<slang::wgsl::GlobalSession>("GlobalSession")
         .function(
             "createSession",
@@ -40,7 +45,10 @@ EMSCRIPTEN_BINDINGS(slang)
             return_value_policy::take_ownership())
         .function(
             "getEntryPointCode",
-            &slang::wgsl::ComponentType::getEntryPointCode);
+            &slang::wgsl::ComponentType::getEntryPointCode)
+        .function(
+            "getEntryPointCodeSpirv",
+            &slang::wgsl::ComponentType::getEntryPointCodeSpirv);
 
     class_<slang::wgsl::Module, base<slang::wgsl::ComponentType>>("Module")
         .function(
@@ -59,5 +67,11 @@ EMSCRIPTEN_BINDINGS(slang)
 
     class_<slang::wgsl::EntryPoint, base<slang::wgsl::ComponentType>>("EntryPoint");
 
+    class_<slang::wgsl::CompileTargets>("CompileTargets")
+        .function(
+            "findCompileTarget",
+            &slang::wgsl::CompileTargets::findCompileTarget,
+            return_value_policy::take_ownership());
+
     register_vector<slang::wgsl::ComponentType*>("ComponentTypeList");
 }
diff --git a/source/slang-wasm/slang-wasm.cpp b/source/slang-wasm/slang-wasm.cpp
index a679a5f3d..6fbe2dc6c 100644
--- a/source/slang-wasm/slang-wasm.cpp
+++ b/source/slang-wasm/slang-wasm.cpp
@@ -14,6 +14,7 @@ namespace wgsl
 {
 
 Error g_error;
+CompileTargets g_compileTargets;
 
 Error getLastError()
 {
@@ -22,6 +23,11 @@ Error getLastError()
     return currentError;
 }
 
+CompileTargets* getCompileTargets()
+{
+    return &g_compileTargets;
+}
+
 GlobalSession* createGlobalSession()
 {
     IGlobalSession* globalSession = nullptr;
@@ -38,7 +44,33 @@ GlobalSession* createGlobalSession()
     return new GlobalSession(globalSession);
 }
 
-Session* GlobalSession::createSession()
+CompileTargets::CompileTargets()
+{
+#define MAKE_PAIR(x) { #x, SLANG_##x }
+
+    m_compileTargetMap = {
+        MAKE_PAIR(GLSL),
+        MAKE_PAIR(HLSL),
+        MAKE_PAIR(WGSL),
+        MAKE_PAIR(SPIRV),
+        MAKE_PAIR(METAL),
+    };
+}
+
+int CompileTargets::findCompileTarget(const std::string& name)
+{
+    auto res = m_compileTargetMap.find(name);
+    if ( res != m_compileTargetMap.end())
+    {
+        return res->second;
+    }
+    else
+    {
+        return SLANG_TARGET_UNKNOWN;
+    }
+}
+
+Session* GlobalSession::createSession(int compileTarget)
 {
     ISession* session = nullptr;
     {
@@ -46,7 +78,7 @@ Session* GlobalSession::createSession()
         sessionDesc.structureSize = sizeof(sessionDesc);
         constexpr SlangInt targetCount = 1;
         TargetDesc target = {};
-        target.format = SLANG_WGSL;
+        target.format = (SlangCompileTarget)compileTarget;
         sessionDesc.targets = &target;
         sessionDesc.targetCount = targetCount;
         SlangResult result = m_interface->createSession(sessionDesc, &session);
@@ -202,5 +234,32 @@ std::string ComponentType::getEntryPointCode(int entryPointIndex, int targetInde
     return {};
 }
 
+// Since spirv code is binary, we can't return it as a string, we will need to use emscripten::val
+// to wrap it and return it to the javascript side.
+emscripten::val ComponentType::getEntryPointCodeSpirv(int entryPointIndex, int targetIndex)
+{
+    Slang::ComPtr<IBlob> kernelBlob;
+    Slang::ComPtr<ISlangBlob> diagnosticBlob;
+    SlangResult result = interface()->getEntryPointCode(
+        entryPointIndex,
+        targetIndex,
+        kernelBlob.writeRef(),
+        diagnosticBlob.writeRef());
+    if (result != SLANG_OK)
+    {
+        g_error.type = std::string("USER");
+        g_error.result = result;
+        g_error.message = std::string(
+            (char*)diagnosticBlob->getBufferPointer(),
+            (char*)diagnosticBlob->getBufferPointer() +
+            diagnosticBlob->getBufferSize());
+        return {};
+    }
+
+    const uint8_t* ptr = (uint8_t*)kernelBlob->getBufferPointer();
+    return emscripten::val(emscripten::typed_memory_view(kernelBlob->getBufferSize(),
+            ptr));
+}
+
 } // namespace wgsl
 } // namespace slang
diff --git a/source/slang-wasm/slang-wasm.h b/source/slang-wasm/slang-wasm.h
index c329716e8..a54cfe1ea 100644
--- a/source/slang-wasm/slang-wasm.h
+++ b/source/slang-wasm/slang-wasm.h
@@ -1,6 +1,8 @@
 #pragma once
 
 #include <slang.h>
+#include <unordered_map>
+#include <emscripten/val.h>
 
 namespace slang
 {
@@ -20,6 +22,17 @@ public:
 
 Error getLastError();
 
+class CompileTargets
+{
+public:
+    CompileTargets();
+    int findCompileTarget(const std::string& name);
+private:
+    std::unordered_map<std::string, SlangCompileTarget> m_compileTargetMap;
+};
+
+CompileTargets* getCompileTargets();
+
 class ComponentType
 {
 public:
@@ -30,6 +43,7 @@ public:
     ComponentType* link();
 
     std::string getEntryPointCode(int entryPointIndex, int targetIndex);
+    emscripten::val getEntryPointCodeSpirv(int entryPointIndex, int targetIndex);
 
     slang::IComponentType* interface() const {return m_interface;}
 
@@ -93,7 +107,7 @@ public:
     GlobalSession(slang::IGlobalSession* interface)
         : m_interface(interface) {}
 
-    Session* createSession();
+    Session* createSession(int compileTarget);
 
     slang::IGlobalSession* interface() const {return m_interface;}