Consider impossible fallthrough scenarios with default blocks as well.

We only checked cases, but default block is also block like any other.
Refactor default blocks to be just a normal case label.

5 files changed, 21 insertions, 11 deletions

diff --git a/cfg_structurizer.cpp b/cfg_structurizer.cpp
index dcaa2ad..d181834 100644
--- a/cfg_structurizer.cpp
+++ b/cfg_structurizer.cpp
@@ -86,7 +86,6 @@ void CFGStructurizer::log_cfg_graphviz(const char *path) const
 		case Terminator::Type::Switch:
 			for (auto &c : node->ir.terminator.cases)
 				fprintf(file, "%u -> %u;\n", get_node_id(node), get_node_id(c.node));
-			fprintf(file, "%u -> %u;\n", get_node_id(node), get_node_id(node->ir.terminator.default_node));
 			break;
 
 		default:
@@ -141,8 +140,12 @@ void CFGStructurizer::log_cfg(const char *tag) const
 		case Terminator::Type::Switch:
 			LOGI("  Switch\n");
 			for (auto &c : node->ir.terminator.cases)
-				LOGI("    Case %u -> %s\n", c.value, c.node->name.c_str());
-			LOGI("    Default -> %s\n", node->ir.terminator.default_node->name.c_str());
+			{
+				if (c.is_default)
+					LOGI("    Default -> %s\n", c.node->name.c_str());
+				else
+					LOGI("    Case %u -> %s\n", c.value, c.node->name.c_str());
+			}
 			break;
 
 		case Terminator::Type::Kill:
@@ -2946,8 +2949,6 @@ void CFGStructurizer::retarget_pred_from(CFGNode *new_node, CFGNode *old_succ)
 			p_term.true_block = new_node;
 		if (p_term.false_block == old_succ)
 			p_term.false_block = new_node;
-		if (p_term.default_node == old_succ)
-			p_term.default_node = new_node;
 		for (auto &c : p_term.cases)
 			if (c.node == old_succ)
 				c.node = new_node;
diff --git a/dxil_converter.cpp b/dxil_converter.cpp
index f36052a..4aa567e 100644
--- a/dxil_converter.cpp
+++ b/dxil_converter.cpp
@@ -5360,7 +5360,12 @@ CFGNode *Converter::Impl::convert_function(llvm::Function *func, CFGNodePool &po
 		else if (auto *inst = llvm::dyn_cast<llvm::SwitchInst>(instruction))
 		{
 			node->ir.terminator.type = Terminator::Type::Switch;
-			node->ir.terminator.default_node = bb_map[inst->getDefaultDest()]->node;
+
+			Terminator::Case default_case = {};
+			default_case.is_default = true;
+			default_case.node = bb_map[inst->getDefaultDest()]->node;
+			node->ir.terminator.cases.push_back(default_case);
+
 			node->ir.terminator.conditional_id = get_id_for_value(inst->getCondition());
 			for (auto itr = inst->case_begin(); itr != inst->case_end(); ++itr)
 			{
diff --git a/ir.hpp b/ir.hpp
index c154037..f02b9f3 100644
--- a/ir.hpp
+++ b/ir.hpp
@@ -164,9 +164,9 @@ struct Terminator
 		CFGNode *node = nullptr;
 		uint64_t global_order = 0;
 		uint32_t value = 0;
+		bool is_default = false;
 	};
 	Vector<Case> cases;
-	CFGNode *default_node = nullptr;
 	uint32_t return_value = 0;
 };
 
diff --git a/node.cpp b/node.cpp
index c077eeb..8581532 100644
--- a/node.cpp
+++ b/node.cpp
@@ -429,8 +429,6 @@ void CFGNode::retarget_branch(CFGNode *to_prev, CFGNode *to_next)
 		ir.terminator.true_block = to_next;
 	if (ir.terminator.false_block == to_prev)
 		ir.terminator.false_block = to_next;
-	if (ir.terminator.default_node == to_prev)
-		ir.terminator.default_node = to_next;
 	for (auto &c : ir.terminator.cases)
 		if (c.node == to_prev)
 			c.node = to_next;
diff --git a/spirv_module.cpp b/spirv_module.cpp
index 6b4f8d6..c7d56db 100644
--- a/spirv_module.cpp
+++ b/spirv_module.cpp
@@ -987,10 +987,16 @@ void SPIRVModule::Impl::emit_basic_block(CFGNode *node)
 	{
 		auto switch_op = std::make_unique<spv::Instruction>(spv::OpSwitch);
 		switch_op->addIdOperand(ir.terminator.conditional_id);
-		switch_op->addIdOperand(ir.terminator.default_node->id);
-		get_spv_block(ir.terminator.default_node)->addPredecessor(bb);
+
+		auto default_itr = std::find_if(ir.terminator.cases.begin(), ir.terminator.cases.end(),
+		                                [](const Terminator::Case &c) { return c.is_default; });
+		assert(default_itr != ir.terminator.cases.end());
+		switch_op->addIdOperand(default_itr->node->id);
+		get_spv_block(default_itr->node)->addPredecessor(bb);
 		for (auto &switch_case : ir.terminator.cases)
 		{
+			if (switch_case.is_default)
+				continue;
 			switch_op->addImmediateOperand(switch_case.value);
 			switch_op->addIdOperand(switch_case.node->id);
 			get_spv_block(switch_case.node)->addPredecessor(bb);