Swift Optimizer: add the dominator and post-dominator tree analysis

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Analysis/CMakeLists.txt

@@ -9,4 +9,6 @@
 swift_compiler_sources(Optimizer
   AliasAnalysis.swift
   CalleeAnalysis.swift
-  DeadEndBlocksAnalysis.swift)
+  DeadEndBlocksAnalysis.swift
+  DominatorTree.swift
+  PostDominatorTree.swift)

SwiftCompilerSources/Sources/Optimizer/Analysis/DominatorTree.swift

@@ -0,0 +1,28 @@
+//===--- DominatorTree.swift - the dominator tree -------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SIL
+import OptimizerBridging
+
+public struct DominatorTree {
+  let bridged: BridgedDomTree
+}
+
+extension BasicBlock {
+  func dominates(_ other: BasicBlock, _ domTree: DominatorTree) -> Bool {
+    DominatorTree_dominates(domTree.bridged, self.bridged, other.bridged) != 0
+  }
+  
+  func strictlyDominates(_ other: BasicBlock, _ domTree: DominatorTree) -> Bool {
+    dominates(other, domTree) && self != other
+  }
+}

SwiftCompilerSources/Sources/Optimizer/Analysis/PostDominatorTree.swift

@@ -0,0 +1,28 @@
+//===--- PostDominatorTree.swift - the post dominator tree ----------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SIL
+import OptimizerBridging
+
+public struct PostDominatorTree {
+  let bridged: BridgedPostDomTree
+}
+
+extension BasicBlock {
+  func postDominates(_ other: BasicBlock, _ pdomTree: PostDominatorTree) -> Bool {
+    PostDominatorTree_postDominates(pdomTree.bridged, self.bridged, other.bridged) != 0
+  }
+  
+  func strictlyPostDominates(_ other: BasicBlock, _ pdomTree: PostDominatorTree) -> Bool {
+    postDominates(other, pdomTree) && self != other
+  }
+}

SwiftCompilerSources/Sources/Optimizer/PassManager/PassUtils.swift

@@ -41,6 +41,16 @@ struct PassContext {
     return DeadEndBlocksAnalysis(bridged: bridgeDEA)
   }
 
+  var dominatorTree: DominatorTree {
+    let bridgedDT = PassContext_getDomTree(_bridged)
+    return DominatorTree(bridged: bridgedDT)
+  }
+
+  var postDominatorTree: PostDominatorTree {
+    let bridgedPDT = PassContext_getPostDomTree(_bridged)
+    return PostDominatorTree(bridged: bridgedPDT)
+  }
+
   func notifyInstructionsChanged() {
     PassContext_notifyChanges(_bridged, instructionsChanged)
   }

include/swift/SILOptimizer/Analysis/DominanceAnalysis.h

@@ -36,6 +36,10 @@ class DominanceAnalysis : public FunctionAnalysisBase<DominanceInfo> {
   DominanceAnalysis(const DominanceAnalysis &) = delete;
   DominanceAnalysis &operator=(const DominanceAnalysis &) = delete;
 
+  static SILAnalysisKind getAnalysisKind() {
+    return SILAnalysisKind::Dominance;
+  }
+
   static bool classof(const SILAnalysis *S) {
     return S->getKind() == SILAnalysisKind::Dominance;
   }
@@ -65,6 +69,10 @@ class PostDominanceAnalysis : public FunctionAnalysisBase<PostDominanceInfo> {
   PostDominanceAnalysis(const PostDominanceAnalysis &) = delete;
   PostDominanceAnalysis &operator=(const PostDominanceAnalysis &) = delete;
 
+  static SILAnalysisKind getAnalysisKind() {
+    return SILAnalysisKind::PostDominance;
+  }
+
   static bool classof(const SILAnalysis *S) {
     return S->getKind() == SILAnalysisKind::PostDominance;
   }

include/swift/SILOptimizer/OptimizerBridging.h

@@ -43,6 +43,14 @@ typedef struct {
   void * _Nullable dea;
 } BridgedDeadEndBlocksAnalysis;
 
+typedef struct {
+  void * _Nullable dt;
+} BridgedDomTree;
+
+typedef struct {
+  void * _Nullable pdt;
+} BridgedPostDomTree;
+
 typedef struct {
   void * _Nonnull opaquePtr;
   unsigned char kind;
@@ -92,6 +100,18 @@ PassContext_getDeadEndBlocksAnalysis(BridgedPassContext context);
 SwiftInt DeadEndBlocksAnalysis_isDeadEnd(BridgedDeadEndBlocksAnalysis debAnalysis,
                                          BridgedBasicBlock);
 
+BridgedDomTree PassContext_getDomTree(BridgedPassContext context);
+
+SwiftInt DominatorTree_dominates(BridgedDomTree domTree,
+                                 BridgedBasicBlock dominating,
+                                 BridgedBasicBlock dominated);
+
+BridgedPostDomTree PassContext_getPostDomTree(BridgedPassContext context);
+
+SwiftInt PostDominatorTree_postDominates(BridgedPostDomTree pdomTree,
+                                         BridgedBasicBlock dominating,
+                                         BridgedBasicBlock dominated);
+
 BridgedSlab PassContext_getNextSlab(BridgedSlab slab);
 BridgedSlab PassContext_getPreviousSlab(BridgedSlab slab);
 BridgedSlab PassContext_allocSlab(BridgedPassContext passContext,

lib/SILOptimizer/PassManager/PassManager.cpp

@@ -23,6 +23,7 @@
 #include "swift/SILOptimizer/Analysis/BasicCalleeAnalysis.h"
 #include "swift/SILOptimizer/Analysis/DeadEndBlocksAnalysis.h"
 #include "swift/SILOptimizer/Analysis/FunctionOrder.h"
+#include "swift/SILOptimizer/Analysis/DominanceAnalysis.h"
 #include "swift/SILOptimizer/OptimizerBridging.h"
 #include "swift/SILOptimizer/PassManager/PrettyStackTrace.h"
 #include "swift/SILOptimizer/PassManager/Transforms.h"
@@ -1249,6 +1250,32 @@ PassContext_getDeadEndBlocksAnalysis(BridgedPassContext context) {
   return {pm->getAnalysis<DeadEndBlocksAnalysis>(invocation->getFunction())};
 }
 
+BridgedDomTree PassContext_getDomTree(BridgedPassContext context) {
+  SwiftPassInvocation *invocation = castToPassInvocation(context);
+  SILPassManager *pm = invocation->getPassManager();
+  return {pm->getAnalysis<DominanceAnalysis>(invocation->getFunction())};
+}
+
+SwiftInt DominatorTree_dominates(BridgedDomTree domTree,
+                                 BridgedBasicBlock dominating,
+                                 BridgedBasicBlock dominated) {
+  DominanceInfo *di = static_cast<DominanceInfo *>(domTree.dt);
+  return di->dominates(castToBasicBlock(dominating), castToBasicBlock(dominated)) ? 1 : 0;
+}
+
+BridgedPostDomTree PassContext_getPostDomTree(BridgedPassContext context) {
+  SwiftPassInvocation *invocation = castToPassInvocation(context);
+  SILPassManager *pm = invocation->getPassManager();
+  return {pm->getAnalysis<PostDominanceAnalysis>(invocation->getFunction())};
+}
+
+SwiftInt PostDominatorTree_postDominates(BridgedPostDomTree pdomTree,
+                                         BridgedBasicBlock dominating,
+                                         BridgedBasicBlock dominated) {
+  auto *pdi = static_cast<PostDominanceInfo *>(pdomTree.pdt);
+  return pdi->dominates(castToBasicBlock(dominating), castToBasicBlock(dominated)) ? 1 : 0;
+}
+
 BridgedBasicBlockSet PassContext_allocBasicBlockSet(BridgedPassContext context) {
   return {castToPassInvocation(context)->allocBlockSet()};
 }