Merge pull request #145 from nevillegrech/cloning_tweaks

New cloner-aiding transformation

logic/local.dl

@@ -59,6 +59,16 @@ clonerHelperInsertor.insertOps(dup,
 ) :-
   beforeClonerLocal.DUPStatementCopiesPushedLabelVar(dup, label).
 
+// We can't clone fallthrough blocks, add a jump in that case
+clonerHelperInsertor.insertOps(fallthrough,
+  LIST(
+    STMT(PUSH4, as(fallthrough, symbol)),
+    STMT(JUMP, "")
+  )
+):-
+  beforeClonerLocal.FallthroughBlockUsedMultipleTimes(_, fallthrough),
+  beforeClonerLocal.JUMPDEST(fallthrough).
+
 COPY_OUTPUT(blockCloner, clonerHelperInsertor)
 // Transformation doesn't introduce new blocks, we can use revertCloner for the original block info
 blockCloner.Prev_Block_OriginalBlock(block, originalBlock):- revertCloner.Block_OriginalBlock(block, originalBlock).

logic/local_components.dl

@@ -628,17 +628,33 @@ IsStackIndexLessThan(n, maximum) :- n = range(0, maximum, 1).
     PrivateFunctionCall(block, _, _, _);
     PrivateFunctionReturn(block).
 
-    .decl FallthroughBlockPushesContinuation(block: Block, fallthrough: Statement)
-  DEBUG_OUTPUT(FallthroughBlockPushesContinuation)
-  FallthroughBlockPushesContinuation(block, fallthrough):-
-    BlockPushesLabel(block, _),
+  // Falthrough edges (excluding JUMPIs)
+  .decl JumplessFalthroughBlock(block: Block, next: Block)
+  JumplessFalthroughBlock(block, next):-
+    FallthroughEdge(block, next),
     BasicBlock_Tail(block, stmt),
-    Statement_Next(stmt, fallthrough),
     !JUMP(stmt),
     !JUMPI(stmt),
     Statement_Opcode(stmt, opcode),
     !OpcodePossiblyHalts(opcode).
 
+  // Insertor heuristic: Fallthrough block likely performs a function call
+  .decl FallthroughBlockPushesContinuation(block: Block, fallthrough: Statement)
+  FallthroughBlockPushesContinuation(block, fallthrough):-
+    BlockPushesLabel(block, _),
+    JumplessFalthroughBlock(block, next),
+    BasicBlock_Head(next, fallthrough).
+
+  // Insertor heuristic: Fallthrough block is used multiple times and its the next is a `StackBalanceBlock`
+  .decl FallthroughBlockUsedMultipleTimes(block: Block, fallthrough: Statement)
+  FallthroughBlockUsedMultipleTimes(block, fallthrough):-
+    JumplessFalthroughBlock(block, next),
+    StackBalanceBlock(next),
+    (BlockPushesLabel(block1, as(block, Value)); StaticBlockJumpTarget(block1, as(block, Value))),
+    (BlockPushesLabel(block2, as(block, Value)); StaticBlockJumpTarget(block2, as(block, Value))),
+    BasicBlock_Head(next, fallthrough),
+    block1 != block2.
+
   .decl CODECOPYStatement(stmt: Statement, offset: Value, size: Value)
   CODECOPYStatement(codeCopy, codeOffsetNumHex, smallNumHex) :-
     Statement_Opcode(codeCopy, "CODECOPY"),

logic/statement_insertor.dl

@@ -355,7 +355,8 @@ INITIALIZE_STATEMENT_INSERTOR(_insertor, to)
     BlockPushesBlockToStack(_, otherFrom, to),
     BlockCloningCandidate(to),
     from != otherFrom,
-    !BlockPushesCloningCandidate(to, _, _),
+    // Don't think we need it after all.
+    // !BlockPushesCloningCandidate(to, _, _),
     !FallthroughBlock(to),
     // Make sure we don't break any CODECOPY stmts
     !analysis.CODECOPYStatement(_, as(to,Value), _).

tests/default-fallback-scalable/2d56cd44e89f2cf76a935c2508f710e7.json

@@ -1,5 +1,5 @@
 {
     "client_path": null,
     "gigahorse_args": ["-i", "--disable_inline"],
-    "expected_analytics": [["Analytics_JumpToMany", 1, 0], ["Analytics_UnreachableBlock", 2, 0]]
+    "expected_analytics": [["Analytics_JumpToMany", 2, 0], ["Analytics_UnreachableBlock", 2, 0]]
 }