Emit matrix layouts in structs directly.

Unlike GLSL, child structs do not inherit matrix layouts.

reference/opt/shaders-hlsl/frag/row-major-layout-in-struct.frag

@@ -0,0 +1,37 @@
+struct Foo
+{
+    row_major float4x4 v;
+    row_major float4x4 w;
+};
+
+cbuffer _17 : register(b0)
+{
+    Foo _17_foo : packoffset(c0);
+};
+
+static float4 FragColor;
+static float4 vUV;
+
+struct SPIRV_Cross_Input
+{
+    float4 vUV : TEXCOORD0;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 FragColor : SV_Target0;
+};
+
+void frag_main()
+{
+    FragColor = mul(mul(vUV, _17_foo.w), _17_foo.v);
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    vUV = stage_input.vUV;
+    frag_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.FragColor = FragColor;
+    return stage_output;
+}

reference/shaders-hlsl/frag/row-major-layout-in-struct.frag

@@ -0,0 +1,46 @@
+struct NonFoo
+{
+    float4x4 v;
+    float4x4 w;
+};
+
+struct Foo
+{
+    row_major float4x4 v;
+    row_major float4x4 w;
+};
+
+cbuffer _17 : register(b0)
+{
+    Foo _17_foo : packoffset(c0);
+};
+
+static float4 FragColor;
+static float4 vUV;
+
+struct SPIRV_Cross_Input
+{
+    float4 vUV : TEXCOORD0;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 FragColor : SV_Target0;
+};
+
+void frag_main()
+{
+    NonFoo f;
+    f.v = _17_foo.v;
+    f.w = _17_foo.w;
+    FragColor = mul(mul(vUV, f.w), f.v);
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    vUV = stage_input.vUV;
+    frag_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.FragColor = FragColor;
+    return stage_output;
+}

shaders-hlsl/frag/row-major-layout-in-struct.frag

@@ -0,0 +1,29 @@
+#version 450
+
+struct Foo
+{
+	mat4 v;
+	mat4 w;
+};
+
+struct NonFoo
+{
+	mat4 v;
+	mat4 w;
+};
+
+layout(std140, binding = 0) uniform UBO
+{
+	layout(column_major) Foo foo;
+};
+
+layout(location = 0) out vec4 FragColor;
+layout(location = 0) in vec4 vUV;
+
+void main()
+{
+	NonFoo f;
+	f.v = foo.v;
+	f.w = foo.w;
+	FragColor = f.v * (f.w * vUV);
+}

spirv_hlsl.cpp

@@ -1778,13 +1778,10 @@ void CompilerHLSL::emit_resources()
 
 string CompilerHLSL::layout_for_member(const SPIRType &type, uint32_t index)
 {
-	auto flags = combined_decoration_for_member(type, index);
+	auto &flags = get_member_decoration_bitset(type.self, index);
 
-	bool is_block = meta[type.self].decoration.decoration_flags.get(DecorationBlock) ||
-	                meta[type.self].decoration.decoration_flags.get(DecorationBufferBlock);
-
-	if (!is_block)
-		return "";
+	// HLSL can emit row_major or column_major decoration in any struct.
+	// Do not try to merge combined decorations for children like in GLSL.
 
 	// Flip the convention. HLSL is a bit odd in that the memory layout is column major ... but the language API is "row-major".
 	// The way to deal with this is to multiply everything in inverse order, and reverse the memory layout.