Prune unreferenced functions from CFG

libyul/backends/evm/ControlFlowGraphBuilder.cpp

@@ -52,12 +52,23 @@ namespace
 /// Removes edges to blocks that are not reachable.
 void cleanUnreachable(CFG& _cfg)
 {
+	// If operation is a function call it adds the callee entry as child
+	auto const addFunctionsEntries = [&_cfg](CFG::BasicBlock* _node, auto&& _addChild)
+	{
+		for (auto const& operation: _node->operations)
+		{
+			if (auto const* functionCall = std::get_if<CFG::FunctionCall>(&operation.operation))
+			{
+				auto const functionInfo = _cfg.functionInfo.at(&(functionCall->function.get()));
+				_addChild(functionInfo.entry);
+			}
+		}
+	};
+
 	// Determine which blocks are reachable from the entry.
 	util::BreadthFirstSearch<CFG::BasicBlock*> reachabilityCheck{{_cfg.entry}};
-	for (auto const& functionInfo: _cfg.functionInfo | ranges::views::values)
-		reachabilityCheck.verticesToTraverse.emplace_back(functionInfo.entry);
-
 	reachabilityCheck.run([&](CFG::BasicBlock* _node, auto&& _addChild) {
+		addFunctionsEntries(_node, _addChild);
 		visit(util::GenericVisitor{
 			[&](CFG::BasicBlock::Jump const& _jump) {
 				_addChild(_jump.target);
@@ -77,6 +88,16 @@ void cleanUnreachable(CFG& _cfg)
 		cxx20::erase_if(node->entries, [&](CFG::BasicBlock* entry) -> bool {
 			return !reachabilityCheck.visited.count(entry);
 		});
+
+	// Remove functions which are never referenced.
+	_cfg.functions.erase(std::remove_if(_cfg.functions.begin(), _cfg.functions.end(), [&](auto const& item) {
+		return !reachabilityCheck.visited.count(_cfg.functionInfo.at(item).entry);
+	}), _cfg.functions.end());
+
+	// Remove functionInfos which are never referenced.
+	cxx20::erase_if(_cfg.functionInfo, [&](auto const& entry) -> bool {
+		return !reachabilityCheck.visited.count(entry.second.entry);
+	});
 }
 
 /// Sets the ``recursive`` member to ``true`` for all recursive function calls.

test/libyul/evmCodeTransform/stackReuse/function_argument_reuse.yul

@@ -1,10 +1,23 @@
 {
     function f(a, b, c) -> x { pop(address()) sstore(a, c) pop(callvalue()) x := b }
+    pop(f(0, 0, 0))
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:88   */
+//     /* "":95:105   */
+//   tag_2
+//     /* "":103:104   */
+//   0x00
+//     /* "":95:105   */
+//   dup1
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":91:106   */
+//   pop
+//     /* "":0:108   */
 //   stop
 //     /* "":6:86   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_argument_reuse_without_retparams.yul

@@ -3,12 +3,23 @@
     mstore(0x80, x)
     if calldataload(0) { sstore(y, y) }
   }
+
+  f(0, 0)
 }
 // ====
-// stackOptimization: true
 // EVMVersion: >=shanghai
+// stackOptimization: true
 // ----
-//     /* "":0:88   */
+//     /* "":90:97   */
+//   tag_2
+//     /* "":95:96   */
+//   0x00
+//     /* "":90:97   */
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":0:99   */
 //   stop
 //     /* "":4:86   */
 // tag_1:
@@ -21,18 +32,18 @@
 //     /* "":50:65   */
 //   calldataload
 //     /* "":47:82   */
-//   tag_2
+//   tag_3
 //   jumpi
 //     /* "":21:86   */
-// tag_3:
+// tag_4:
 //     /* "":4:86   */
 //   pop
 //   jump	// out
 //     /* "":66:82   */
-// tag_2:
+// tag_3:
 //     /* "":68:80   */
 //   dup1
 //   sstore
 //     /* "":66:82   */
 //   0x00
-//   jump(tag_3)
+//   jump(tag_4)

test/libyul/evmCodeTransform/stackReuse/function_many_arguments.yul

@@ -21,11 +21,42 @@
         mstore(0x0340, a19)
         x := a20
     }
+
+    pop(f(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0))
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:662   */
+//     /* "":670:731   */
+//   tag_2
+//     /* "":729:730   */
+//   0x00
+//     /* "":670:731   */
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":666:732   */
+//   pop
+//     /* "":0:734   */
 //   stop
 //     /* "":6:660   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_params.yul

@@ -1,10 +1,21 @@
 {
     function f(a, b) { }
+
+    f(0, 0)
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:28   */
+//     /* "":32:39   */
+//   tag_2
+//     /* "":37:38   */
+//   0x00
+//     /* "":32:39   */
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":0:41   */
 //   stop
 //     /* "":6:26   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_params_and_retparams.yul

@@ -4,11 +4,24 @@
 // can be reused.
 {
     function f(a, b, c, d) -> x, y { }
+
+    let x, y := f(0, 0, 0, 0)
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":210:252   */
+//     /* "":268:281   */
+//   tag_2
+//     /* "":279:280   */
+//   0x00
+//     /* "":268:281   */
+//   dup1
+//   dup1
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":210:283   */
 //   stop
 //     /* "":216:250   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_params_and_retparams_partly_used.yul

@@ -1,10 +1,23 @@
 {
     function f(a, b, c, d) -> x, y { b := 3 let s := 9 y := 2 mstore(s, y) }
+
+     let x, y := f(0, 0, 0, 0)
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:80   */
+//     /* "":97:110   */
+//   tag_2
+//     /* "":108:109   */
+//   0x00
+//     /* "":97:110   */
+//   dup1
+//   dup1
+//   dup1
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":0:112   */
 //   stop
 //     /* "":6:78   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_retparam.yul

@@ -1,10 +1,17 @@
 {
     function f() -> x, y { }
+
+     let x, y := f()
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:32   */
+//     /* "":49:52   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":0:54   */
 //   stop
 //     /* "":6:30   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_retparam_block.yul

@@ -1,10 +1,19 @@
 {
     function f() -> x { pop(address()) { pop(callvalue()) } }
+
+     pop(f())
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:65   */
+//     /* "":74:77   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":70:78   */
+//   pop
+//     /* "":0:80   */
 //   stop
 //     /* "":6:63   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_retparam_declaration.yul

@@ -1,10 +1,19 @@
 {
     function f() -> x { pop(address()) let y := callvalue() }
+
+     pop(f())
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:65   */
+//     /* "":74:77   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":70:78   */
+//   pop
+//     /* "":0:80   */
 //   stop
 //     /* "":6:63   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_retparam_for.yul

@@ -1,10 +1,19 @@
 {
     function f() -> x { pop(address()) for { pop(callvalue()) } 0 {} { } }
+
+    pop(f())
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:78   */
+//     /* "":86:89   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":82:90   */
+//   pop
+//     /* "":0:92   */
 //   stop
 //     /* "":6:76   */
 // tag_1:

test/libyul/evmCodeTransform/stackReuse/function_retparam_if.yul

@@ -1,10 +1,19 @@
 {
     function f() -> x { pop(address()) if 1 { pop(callvalue()) } }
+
+    pop(f())
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:70   */
+//     /* "":78:81   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":74:82   */
+//   pop
+//     /* "":0:84   */
 //   stop
 //     /* "":6:68   */
 // tag_1:
@@ -19,17 +28,17 @@
 //     /* "":26:40   */
 //   pop
 //     /* "":41:66   */
-//   tag_2
+//   tag_3
 //   jumpi
 //     /* "":24:68   */
-// tag_3:
+// tag_4:
 //     /* "":6:68   */
 //   jump	// out
 //     /* "":46:66   */
-// tag_2:
+// tag_3:
 //     /* "":52:63   */
 //   callvalue
 //     /* "":48:64   */
 //   pop
 //     /* "":46:66   */
-//   jump(tag_3)
+//   jump(tag_4)

test/libyul/evmCodeTransform/stackReuse/function_retparam_leave.yul

@@ -1,10 +1,19 @@
 {
     function f() -> x { pop(address()) leave pop(callvalue()) }
+
+    pop(f())
 }
 // ====
 // stackOptimization: true
 // ----
-//     /* "":0:67   */
+//     /* "":75:78   */
+//   tag_2
+//   tag_1
+//   jump	// in
+// tag_2:
+//     /* "":71:79   */
+//   pop
+//     /* "":0:81   */
 //   stop
 //     /* "":6:65   */
 // tag_1: