[PATCH] D70619: [NFC][LoopFusion] Use isControlFlowEquivalent() from CodeMoverUtils.

[Whitney Tsang via Phabricator via llvm-commits]

Whitney created this revision.
Whitney added reviewers: kbarton, jdoerfert, Meinersbur, bmahjour, etiotto.
Whitney added a project: LLVM.
Herald added subscribers: llvm-commits, hiraditya.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70619

Files:
  llvm/include/llvm/Transforms/Utils/CodeMoverUtils.h
  llvm/lib/Transforms/Scalar/LoopFuse.cpp
  llvm/lib/Transforms/Utils/CodeMoverUtils.cpp


Index: llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
+++ llvm/lib/Transforms/Utils/CodeMoverUtils.cpp
@@ -33,10 +33,14 @@
 bool llvm::isControlFlowEquivalent(const Instruction &I0, const Instruction &I1,
                                    const DominatorTree &DT,
                                    const PostDominatorTree &PDT) {
-  const BasicBlock *BB0 = I0.getParent();
-  const BasicBlock *BB1 = I1.getParent();
-  return ((DT.dominates(BB0, BB1) && PDT.dominates(BB1, BB0)) ||
-          (PDT.dominates(BB0, BB1) && DT.dominates(BB1, BB0)));
+  return isControlFlowEquivalent(*I0.getParent(), *I1.getParent(), DT, PDT);
+}
+
+bool llvm::isControlFlowEquivalent(const BasicBlock &BB0, const BasicBlock &BB1,
+                                   const DominatorTree &DT,
+                                   const PostDominatorTree &PDT) {
+  return ((DT.dominates(&BB0, &BB1) && PDT.dominates(&BB1, &BB0)) ||
+          (PDT.dominates(&BB0, &BB1) && DT.dominates(&BB1, &BB0)));
 }
 
 static bool reportInvalidCandidate(const Instruction &I,
Index: llvm/lib/Transforms/Scalar/LoopFuse.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -63,6 +63,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/CodeMoverUtils.h"
 
 using namespace llvm;
 
@@ -593,16 +594,8 @@
                                const FusionCandidate &FC1) const {
     assert(FC0.Preheader && FC1.Preheader && "Expecting valid preheaders");
 
-    BasicBlock *FC0EntryBlock = FC0.getEntryBlock();
-    BasicBlock *FC1EntryBlock = FC1.getEntryBlock();
-
-    if (DT.dominates(FC0EntryBlock, FC1EntryBlock))
-      return PDT.dominates(FC1EntryBlock, FC0EntryBlock);
-
-    if (DT.dominates(FC1EntryBlock, FC0EntryBlock))
-      return PDT.dominates(FC0EntryBlock, FC1EntryBlock);
-
-    return false;
+    return ::isControlFlowEquivalent(*FC0.getEntryBlock(), *FC1.getEntryBlock(),
+                                     DT, PDT);
   }
 
   /// Iterate over all loops in the given loop set and identify the loops that
Index: llvm/include/llvm/Transforms/Utils/CodeMoverUtils.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/CodeMoverUtils.h
+++ llvm/include/llvm/Transforms/Utils/CodeMoverUtils.h
@@ -16,6 +16,7 @@
 
 namespace llvm {
 
+class BasicBlock;
 class DependenceInfo;
 class DominatorTree;
 class Instruction;
@@ -30,6 +31,15 @@
                              const DominatorTree &DT,
                              const PostDominatorTree &PDT);
 
+/// Return true if \p BB0 and \p BB1 are control flow equivalent.
+/// Two basic blocks are control flow equivalent if when one executes, the other
+/// is guaranteed to execute. This is determined using dominators and
+/// post-dominators: if A dominates B and B post-dominates A then A and B are
+/// control-flow equivalent.
+bool isControlFlowEquivalent(const BasicBlock &BB0, const BasicBlock &BB1,
+                             const DominatorTree &DT,
+                             const PostDominatorTree &PDT);
+
 /// Return true if \p I can be safely moved before \p InsertPoint.
 bool isSafeToMoveBefore(Instruction &I, Instruction &InsertPoint,
                         const DominatorTree &DT, const PostDominatorTree &PDT,


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