rsx/fp: Fix issues with FP decompiler using new CFG system

rpcs3/Emu/RSX/Program/Assembler/FPToCFG.cpp

@@ -100,15 +100,16 @@ namespace rsx::assembler
 
 			if (found)
 			{
-				if (!bb->pred.empty())
+				auto front_edge = std::find_if(bb->pred.begin(), bb->pred.end(), FN(x.type != EdgeType::ENDIF && x.type != EdgeType::ENDLOOP));
+				if (front_edge != bb->pred.end())
 				{
-					switch (bb->pred.back().type)
+					auto parent = ensure(front_edge->from);
+					switch (front_edge->type)
 					{
 					case EdgeType::IF:
 					case EdgeType::ELSE:
 					{
 						// Find the merge node from the parent
-						auto parent = bb->pred.back().from;
 						auto succ = std::find_if(parent->succ.begin(), parent->succ.end(), FN(x.type == EdgeType::ENDIF));
 						ensure(succ != parent->succ.end(), "CFG: Broken IF linkage. Please report to developers.");
 						bb->insert_succ(succ->to, EdgeType::ENDIF);
@@ -118,7 +119,6 @@ namespace rsx::assembler
 					case EdgeType::LOOP:
 					{
 						// Find the merge node from the parent
-						auto parent = bb->pred.back().from;
 						auto succ = std::find_if(parent->succ.begin(), parent->succ.end(), FN(x.type == EdgeType::ENDLOOP));
 						ensure(succ != parent->succ.end(), "CFG: Broken LOOP linkage. Please report to developers.");
 						bb->insert_succ(succ->to, EdgeType::ENDLOOP);
@@ -130,7 +130,7 @@ namespace rsx::assembler
 						rsx_log.error("CFG: Unexpected block exit. Report to developers.");
 					}
 				}
-				else
+				else if (bb->pred.empty())
 				{
 					// Impossible situation.
 					rsx_log.error("CFG: Child block has no parent but has successor! Report to developers.");

rpcs3/Emu/RSX/Program/Assembler/IR.h

@@ -114,5 +114,25 @@ namespace rsx::assembler
 			pred.push_back(e);
 			return &pred.back();
 		}
+
+		bool is_of_type(EdgeType type) const
+		{
+			return pred.size() == 1 &&
+				pred.front().type == type;
+		}
+
+		bool has_sibling_of_type(EdgeType type) const
+		{
+			if (pred.size() != 1)
+			{
+				return false;
+			}
+
+			auto source_node = pred.front().from;
+			return std::find_if(
+				source_node->succ.begin(),
+				source_node->succ.end(),
+				FN(x.type == type)) != source_node->succ.end();
+		}
 	};
 }

rpcs3/Emu/RSX/Program/FragmentProgramDecompiler.cpp

@@ -21,6 +21,7 @@ namespace rsx
 }
 
 using namespace rsx::fragment_program;
+using namespace rsx::assembler;
 
 // SIMD vector lanes
 enum VectorLane : u8
@@ -1295,7 +1296,7 @@ bool FragmentProgramDecompiler::handle_tex_srb(u32 opcode)
 
 std::string FragmentProgramDecompiler::Decompile()
 {
-	const auto graph = rsx::assembler::deconstruct_fragment_program(m_prog);
+	const auto graph = deconstruct_fragment_program(m_prog);
 	m_size = 0;
 	m_location = 0;
 	m_loop_count = 0;
@@ -1322,22 +1323,41 @@ std::string FragmentProgramDecompiler::Decompile()
 			{
 				switch (pred.type)
 				{
-				case rsx::assembler::EdgeType::ENDLOOP:
+				case EdgeType::ENDLOOP:
-					m_loop_count--;
+					// Because of succession rules, endloop is seen twice.
-					[[ fallthrough ]];
+					// Once from the the for statement at the end of the parent
-				case rsx::assembler::EdgeType::ENDIF:
+					// and again at the end of the child block.
-					m_code_level--;
+					if (pred.from->is_of_type(EdgeType::LOOP))
-					AddCode("}");
+					{
+						m_loop_count--;
+						m_code_level--;
+						AddCode("}");
+					}
 					break;
-				case rsx::assembler::EdgeType::LOOP:
+				case EdgeType::ENDIF:
+				{
+					// Same thing happens with ENDIF
+					// Once for the IF statement itself
+					// And again for the child blocks with code for the IF and ELSE paths.
+					const bool is_else_end = pred.from->is_of_type(EdgeType::ELSE);
+					const bool is_if_end = pred.from->is_of_type(EdgeType::IF) &&
+						!pred.from->has_sibling_of_type(EdgeType::ELSE); // Avoid double-counting if the IF has an ELSE sibling
+					if (is_else_end || is_if_end)
+					{
+						m_code_level--;
+						AddCode("}");
+					}
+					break;
+				}
+				case EdgeType::LOOP:
 					m_loop_count++;
 					[[ fallthrough ]];
-				case rsx::assembler::EdgeType::IF:
+				case EdgeType::IF:
 					// Instruction will be inserted by the SIP decoder
 					AddCode("{");
 					m_code_level++;
 					break;
-				case rsx::assembler::EdgeType::ELSE:
+				case EdgeType::ELSE:
 					// This one needs more testing
 					m_code_level--;
 					AddCode("}");
@@ -1440,8 +1460,8 @@ std::string FragmentProgramDecompiler::Decompile()
 
 	while (m_code_level > 1)
 	{
-		rsx_log.error("Hanging block found at end of shader. Malformed shader?");
+		// Happens if the last block was hanging (no merge)
-
+		// FIXME: We must always have a merge block on exit to resolve dependencies on outputs
 		m_code_level--;
 		AddCode("}");
 	}