diff options
| -rw-r--r-- | zjit/src/hir.rs | 85 |
1 files changed, 66 insertions, 19 deletions
diff --git a/zjit/src/hir.rs b/zjit/src/hir.rs index 2bd7174f2d..7a9bb132aa 100644 --- a/zjit/src/hir.rs +++ b/zjit/src/hir.rs @@ -1792,6 +1792,67 @@ impl Function { } } + fn absorb_dst_block(&mut self, num_in_edges: &Vec<u32>, block: BlockId) -> bool { + let Some(terminator_id) = self.blocks[block.0].insns.last() + else { return false }; + let Insn::Jump(BranchEdge { target, args }) = self.find(*terminator_id) + else { return false }; + if target == block { + // Can't absorb self + return false; + } + if num_in_edges[target.0] != 1 { + // Can't absorb block if it's the target of more than one branch + return false; + } + // Link up params with block args + let params = std::mem::take(&mut self.blocks[target.0].params); + assert_eq!(args.len(), params.len()); + for (arg, param) in args.iter().zip(params) { + self.make_equal_to(param, *arg); + } + // Remove branch instruction + self.blocks[block.0].insns.pop(); + // Move target instructions into block + let target_insns = std::mem::take(&mut self.blocks[target.0].insns); + self.blocks[block.0].insns.extend(target_insns); + true + } + + /// Clean up linked lists of blocks A -> B -> C into A (with B's and C's instructions). + fn clean_cfg(&mut self) { + // num_in_edges is invariant throughout cleaning the CFG: + // * we don't allocate new blocks + // * blocks that get absorbed are not in RPO anymore + // * blocks pointed to by blocks that get absorbed retain the same number of in-edges + let mut num_in_edges = vec![0; self.blocks.len()]; + for block in self.rpo() { + for &insn in &self.blocks[block.0].insns { + if let Insn::IfTrue { target, .. } | Insn::IfFalse { target, .. } | Insn::Jump(target) = self.find(insn) { + num_in_edges[target.target.0] += 1; + } + } + } + let mut changed = false; + loop { + let mut iter_changed = false; + for block in self.rpo() { + // Ignore transient empty blocks + if self.blocks[block.0].insns.is_empty() { continue; } + loop { + let absorbed = self.absorb_dst_block(&num_in_edges, block); + if !absorbed { break; } + iter_changed = true; + } + } + if !iter_changed { break; } + changed = true; + } + if changed { + self.infer_types(); + } + } + /// Return a traversal of the `Function`'s `BlockId`s in reverse post-order. pub fn rpo(&self) -> Vec<BlockId> { let mut result = self.po_from(self.entry_block); @@ -1831,6 +1892,7 @@ impl Function { self.optimize_direct_sends(); self.optimize_c_calls(); self.fold_constants(); + self.clean_cfg(); self.eliminate_dead_code(); // Dump HIR after optimization @@ -4455,9 +4517,6 @@ mod opt_tests { assert_optimized_method_hir("test", expect![[r#" fn test: bb0(v0:BasicObject): - v3:FalseClassExact = Const Value(false) - Jump bb1(v0, v3) - bb1(v8:BasicObject, v9:FalseClassExact): v11:Fixnum[4] = Const Value(4) Return v11 "#]]); @@ -4634,8 +4693,6 @@ mod opt_tests { fn test: bb0(v0:BasicObject): PatchPoint BOPRedefined(INTEGER_REDEFINED_OP_FLAG, BOP_EQ) - Jump bb1(v0) - bb1(v10:BasicObject): v12:Fixnum[4] = Const Value(4) Return v12 "#]]); @@ -4698,8 +4755,6 @@ mod opt_tests { bb0(v0:BasicObject): PatchPoint BOPRedefined(INTEGER_REDEFINED_OP_FLAG, BOP_EQ) PatchPoint BOPRedefined(INTEGER_REDEFINED_OP_FLAG, BOP_NEQ) - Jump bb1(v0) - bb1(v10:BasicObject): v12:Fixnum[4] = Const Value(4) Return v12 "#]]); @@ -5644,12 +5699,8 @@ mod opt_tests { PatchPoint StableConstantNames(0x1000, C) v20:BasicObject[VALUE(0x1008)] = Const Value(VALUE(0x1008)) v4:NilClassExact = Const Value(nil) - Jump bb1(v0, v4, v20) - bb1(v6:BasicObject, v7:NilClassExact, v8:BasicObject[VALUE(0x1008)]): - v11:BasicObject = SendWithoutBlock v8, :new - Jump bb2(v6, v11, v7) - bb2(v13:BasicObject, v14:BasicObject, v15:NilClassExact): - Return v14 + v11:BasicObject = SendWithoutBlock v20, :new + Return v11 "#]]); } @@ -5672,12 +5723,8 @@ mod opt_tests { v22:BasicObject[VALUE(0x1008)] = Const Value(VALUE(0x1008)) v4:NilClassExact = Const Value(nil) v5:Fixnum[1] = Const Value(1) - Jump bb1(v0, v4, v22, v5) - bb1(v7:BasicObject, v8:NilClassExact, v9:BasicObject[VALUE(0x1008)], v10:Fixnum[1]): - v13:BasicObject = SendWithoutBlock v9, :new, v10 - Jump bb2(v7, v13, v8) - bb2(v15:BasicObject, v16:BasicObject, v17:NilClassExact): - Return v16 + v13:BasicObject = SendWithoutBlock v22, :new, v5 + Return v13 "#]]); } |