Add bgra8 format (#6163)

* add brga8 format

* add tests

* minor fixes

* cleanup

* maybe fix broken quad control test

* add missing xslang flag on test

---------

Co-authored-by: Yong He <yonghe@outlook.com>

5 files changed, 53 insertions, 5 deletions

diff --git a/source/slang/slang-diagnostic-defs.h b/source/slang/slang-diagnostic-defs.h
index 37dfc8114..cf338edfa 100644
--- a/source/slang/slang-diagnostic-defs.h
+++ b/source/slang/slang-diagnostic-defs.h
@@ -1059,6 +1059,13 @@ DIAGNOSTIC(
     explicitUniformLocation,
     "Explicit binding of uniform locations is discouraged. Prefer 'ConstantBuffer<$0>' over "
     "'uniform $0'")
+DIAGNOSTIC(
+    31105,
+    Warning,
+    imageFormatUnsupportedByBackend,
+    "Image format '$0' is not explicitly supported by the $1 backend, using supported format '$2' "
+    "instead.")
+
 
 DIAGNOSTIC(31120, Error, invalidAttributeTarget, "invalid syntax target for user defined attribute")
 
diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index b94f44690..61457d98e 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -608,6 +608,19 @@ void GLSLSourceEmitter::_emitGLSLParameterGroup(
     m_writer->emit(";\n");
 }
 
+static bool isImageFormatSupportedByGLSL(ImageFormat format)
+{
+    switch (format)
+    {
+    case ImageFormat::bgra8:
+        // These are formats Slang accept, but are not explicitly supported in GLSL.
+        return false;
+    default:
+        return true;
+    }
+};
+
+
 void GLSLSourceEmitter::_emitGLSLImageFormatModifier(IRInst* var, IRTextureType* resourceType)
 {
     SLANG_UNUSED(resourceType);
@@ -618,6 +631,18 @@ void GLSLSourceEmitter::_emitGLSLImageFormatModifier(IRInst* var, IRTextureType*
     if (auto formatDecoration = var->findDecoration<IRFormatDecoration>())
     {
         auto format = formatDecoration->getFormat();
+        const auto formatInfo = getImageFormatInfo(format);
+        if (!isImageFormatSupportedByGLSL(format))
+        {
+            getSink()->diagnose(
+                SourceLoc(),
+                Diagnostics::imageFormatUnsupportedByBackend,
+                formatInfo.name,
+                "GLSL",
+                "unknown");
+            format = ImageFormat::unknown;
+        }
+
         if (format == ImageFormat::unknown)
         {
             // If the user explicitly opts out of having a format, then
@@ -636,7 +661,6 @@ void GLSLSourceEmitter::_emitGLSLImageFormatModifier(IRInst* var, IRTextureType*
         }
         else
         {
-            auto formatInfo = getImageFormatInfo(format);
             if (formatInfo.scalarType == SLANG_SCALAR_TYPE_UINT64 ||
                 formatInfo.scalarType == SLANG_SCALAR_TYPE_INT64)
             {
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 951507ab9..7c2e80846 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -1901,7 +1901,7 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         }
     }
 
-    static SpvImageFormat getSpvImageFormat(IRTextureTypeBase* type)
+    SpvImageFormat getSpvImageFormat(IRTextureTypeBase* type)
     {
         ImageFormat imageFormat =
             type->hasFormat() ? (ImageFormat)type->getFormat() : ImageFormat::unknown;
@@ -1992,7 +1992,14 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         case ImageFormat::r64i:
             return SpvImageFormatR64i;
         default:
-            SLANG_UNIMPLEMENTED_X("unknown image format for spirv emit");
+            const auto imageFormatInfo = getImageFormatInfo(imageFormat);
+            m_sink->diagnose(
+                SourceLoc(),
+                Diagnostics::imageFormatUnsupportedByBackend,
+                imageFormatInfo.name,
+                "SPIRV",
+                "unknown");
+            return SpvImageFormatUnknown;
         }
     }
 
diff --git a/source/slang/slang-emit-wgsl.cpp b/source/slang/slang-emit-wgsl.cpp
index 30a7af938..ce60cc2a0 100644
--- a/source/slang/slang-emit-wgsl.cpp
+++ b/source/slang/slang-emit-wgsl.cpp
@@ -326,7 +326,7 @@ void WGSLSourceEmitter::emit(const AddressSpace addressSpace)
     }
 }
 
-static const char* getWgslImageFormat(IRTextureTypeBase* type)
+const char* WGSLSourceEmitter::getWgslImageFormat(IRTextureTypeBase* type)
 {
     // You can find the supported WGSL texel format from the URL:
     // https://www.w3.org/TR/WGSL/#storage-texel-formats
@@ -405,11 +405,19 @@ static const char* getWgslImageFormat(IRTextureTypeBase* type)
         return "rgba32sint";
     case ImageFormat::rgba32f:
         return "rgba32float";
+    case ImageFormat::bgra8:
+        return "bgra8unorm";
     case ImageFormat::unknown:
         // Unlike SPIR-V, WGSL doesn't have a texel format for "unknown".
         return "rgba32float";
     default:
-        // We may need to print a warning for types WGSL doesn't support
+        const auto imageFormatInfo = getImageFormatInfo(imageFormat);
+        getSink()->diagnose(
+            SourceLoc(),
+            Diagnostics::imageFormatUnsupportedByBackend,
+            imageFormatInfo.name,
+            "WGSL",
+            "rgba32float");
         return "rgba32float";
     }
 }
diff --git a/source/slang/slang-emit-wgsl.h b/source/slang/slang-emit-wgsl.h
index 4e0c18821..714a722d7 100644
--- a/source/slang/slang-emit-wgsl.h
+++ b/source/slang/slang-emit-wgsl.h
@@ -71,6 +71,8 @@ private:
         const IRIntegerValue& rowCountWGSL,
         const IRIntegerValue& colCountWGSL);
 
+    const char* getWgslImageFormat(IRTextureTypeBase* type);
+
     bool m_f16ExtensionEnabled = false;
 };