Refactor replaceDominatedUsesWith to have a flag to control whether to replace uses in BB itself.

Summary: This is in preparation for LoopSink pass which calls replaceDominatedUsesWith to update after sinking.

Reviewers: chandlerc, davidxl, danielcdh

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D24170

llvm-svn: 280427

3 files changed, 10 insertions, 6 deletions

diff --git a/llvm/include/llvm/Transforms/Utils/Local.h b/llvm/include/llvm/Transforms/Utils/Local.h
index b6f9e7f5735..e005b28b453 100644
--- a/llvm/include/llvm/Transforms/Utils/Local.h
+++ b/llvm/include/llvm/Transforms/Utils/Local.h
@@ -326,10 +326,12 @@ void combineMetadataForCSE(Instruction *K, const Instruction *J);
 /// the given edge.  Returns the number of replacements made.
 unsigned replaceDominatedUsesWith(Value *From, Value *To, DominatorTree &DT,
                                   const BasicBlockEdge &Edge);
+
 /// Replace each use of 'From' with 'To' if that use is dominated by
-/// the end of the given BasicBlock. Returns the number of replacements made.
+/// the end of 'BB'. Returns the number of replacements made.
+/// Replace use of 'From' with 'To' in 'BB' if 'IncludeSelf' is true.
 unsigned replaceDominatedUsesWith(Value *From, Value *To, DominatorTree &DT,
-                                  const BasicBlock *BB);
+                                  const BasicBlock *BB, bool IncludeSelf);
 
 
 /// Return true if the CallSite CS calls a gc leaf function.
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index a108ce8d292..aaec475a682 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1962,7 +1962,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
       unsigned NumReplacements =
           DominatesByEdge
               ? replaceDominatedUsesWith(LHS, RHS, *DT, Root)
-              : replaceDominatedUsesWith(LHS, RHS, *DT, Root.getStart());
+              : replaceDominatedUsesWith(LHS, RHS, *DT, Root.getStart(), false);
 
       Changed |= NumReplacements > 0;
       NumGVNEqProp += NumReplacements;
@@ -2038,7 +2038,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
               DominatesByEdge
                   ? replaceDominatedUsesWith(NotCmp, NotVal, *DT, Root)
                   : replaceDominatedUsesWith(NotCmp, NotVal, *DT,
-                                             Root.getStart());
+                                             Root.getStart(), false);
           Changed |= NumReplacements > 0;
           NumGVNEqProp += NumReplacements;
         }
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 87524e660f0..b347bad9958 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1679,7 +1679,8 @@ unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
 
 unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
                                         DominatorTree &DT,
-                                        const BasicBlock *BB) {
+                                        const BasicBlock *BB,
+                                        bool IncludeSelf) {
   assert(From->getType() == To->getType());
 
   unsigned Count = 0;
@@ -1687,7 +1688,8 @@ unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
        UI != UE;) {
     Use &U = *UI++;
     auto *I = cast<Instruction>(U.getUser());
-    if (DT.properlyDominates(BB, I->getParent())) {
+    if ((IncludeSelf && BB == I->getParent()) ||
+        DT.properlyDominates(BB, I->getParent())) {
       U.set(To);
       DEBUG(dbgs() << "Replace dominated use of '" << From->getName() << "' as "
                    << *To << " in " << *U << "\n");