Shader/SPIRV: Fix multiple branch handling (by splitting)

tests/Engine/Shader/Branch.cpp

@@ -144,6 +144,130 @@ OpBranchConditional
 OpLabel
 OpKill
 OpLabel
+OpBranch
+OpLabel
+OpReturn
+OpFunctionEnd)");
+	}
+
+	
+	WHEN("using a complex branch")
+	{
+		std::string_view nzslSource = R"(
+struct inputStruct
+{
+	value: f32
+}
+
+external
+{
+	[set(0), binding(0)] data: uniform<inputStruct>
+}
+
+[entry(frag)]
+fn main()
+{
+	let value: f32;
+	if (data.value > 3.0)
+		value = 3.0;
+	else if (data.value > 2.0)
+		value = 2.0;
+	else if (data.value > 1.0)
+		value = 1.0;
+	else
+		value = 0.0;
+}
+)";
+
+		Nz::ShaderAst::StatementPtr shader = Nz::ShaderLang::Parse(nzslSource);
+
+		ExpectGLSL(*shader, R"(
+void main()
+{
+	float value;
+	if (data.value > (3.000000))
+	{
+		value = 3.000000;
+	}
+	else if (data.value > (2.000000))
+	{
+		value = 2.000000;
+	}
+	else if (data.value > (1.000000))
+	{
+		value = 1.000000;
+	}
+	else
+	{
+		value = 0.000000;
+	}
+	
+}
+)");
+
+		ExpectNZSL(*shader, R"(
+[entry(frag)]
+fn main()
+{
+	let value: f32;
+	if (data.value > (3.000000))
+	{
+		value = 3.000000;
+	}
+	else if (data.value > (2.000000))
+	{
+		value = 2.000000;
+	}
+	else if (data.value > (1.000000))
+	{
+		value = 1.000000;
+	}
+	else
+	{
+		value = 0.000000;
+	}
+	
+}
+)");
+
+		ExpectSpirV(*shader, R"(
+OpFunction
+OpLabel
+OpVariable
+OpAccessChain
+OpLoad
+OpFOrdGreaterThanEqual
+OpSelectionMerge
+OpBranchConditional
+OpLabel
+OpStore
+OpBranch
+OpLabel
+OpAccessChain
+OpLoad
+OpFOrdGreaterThanEqual
+OpSelectionMerge
+OpBranchConditional
+OpLabel
+OpStore
+OpBranch
+OpLabel
+OpAccessChain
+OpLoad
+OpFOrdGreaterThanEqual
+OpSelectionMerge
+OpBranchConditional
+OpLabel
+OpStore
+OpBranch
+OpLabel
+OpStore
+OpBranch
+OpLabel
+OpBranch
+OpLabel
+OpBranch
+OpLabel
 OpReturn
 OpFunctionEnd)");
 	}