[llvm] 82dcd38 - [VPlan] Properly update users when updating operands.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-10-03T20:54:58+01:00
New Revision: 82dcd383c422f03c2b399af5b94701365cdf1afa

URL: https://github.com/llvm/llvm-project/commit/82dcd383c422f03c2b399af5b94701365cdf1afa
DIFF: https://github.com/llvm/llvm-project/commit/82dcd383c422f03c2b399af5b94701365cdf1afa.diff

LOG: [VPlan] Properly update users when updating operands.

When updating operands of a VPUser, we also have to adjust the list of
users for the new and old VPValues. This is required once we start
transitioning recipes to become VPValues.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/VPlanValue.h
    llvm/unittests/Transforms/Vectorize/VPlanTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/VPlanValue.h b/llvm/lib/Transforms/Vectorize/VPlanValue.h
index 50cf1285dd4b..0882837170f2 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanValue.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanValue.h
@@ -97,6 +97,22 @@ class VPValue {
   unsigned getNumUsers() const { return Users.size(); }
   void addUser(VPUser &User) { Users.push_back(&User); }
 
+  /// Remove a single \p User from the list of users.
+  void removeUser(VPUser &User) {
+    bool Found = false;
+    // The same user can be added multiple times, e.g. because the same VPValue
+    // is used twice by the same VPUser. Remove a single one.
+    erase_if(Users, [&User, &Found](VPUser *Other) {
+      if (Found)
+        return false;
+      if (Other == &User) {
+        Found = true;
+        return true;
+      }
+      return false;
+    });
+  }
+
   typedef SmallVectorImpl<VPUser *>::iterator user_iterator;
   typedef SmallVectorImpl<VPUser *>::const_iterator const_user_iterator;
   typedef iterator_range<user_iterator> user_range;
@@ -164,7 +180,11 @@ class VPUser {
     return Operands[N];
   }
 
-  void setOperand(unsigned I, VPValue *New) { Operands[I] = New; }
+  void setOperand(unsigned I, VPValue *New) {
+    Operands[I]->removeUser(*this);
+    Operands[I] = New;
+    New->addUser(*this);
+  }
 
   typedef SmallVectorImpl<VPValue *>::iterator operand_iterator;
   typedef SmallVectorImpl<VPValue *>::const_iterator const_operand_iterator;

diff  --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index 46d9899cd054..a64f9e374ebf 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -87,6 +87,92 @@ TEST(VPInstructionTest, moveAfter) {
   EXPECT_EQ(I3->getParent(), I4->getParent());
 }
 
+TEST(VPInstructionTest, setOperand) {
+  VPValue *VPV1 = new VPValue();
+  VPValue *VPV2 = new VPValue();
+  VPInstruction *I1 = new VPInstruction(0, {VPV1, VPV2});
+  EXPECT_EQ(1u, VPV1->getNumUsers());
+  EXPECT_EQ(I1, *VPV1->user_begin());
+  EXPECT_EQ(1u, VPV2->getNumUsers());
+  EXPECT_EQ(I1, *VPV2->user_begin());
+
+  // Replace operand 0 (VPV1) with VPV3.
+  VPValue *VPV3 = new VPValue();
+  I1->setOperand(0, VPV3);
+  EXPECT_EQ(0u, VPV1->getNumUsers());
+  EXPECT_EQ(1u, VPV2->getNumUsers());
+  EXPECT_EQ(I1, *VPV2->user_begin());
+  EXPECT_EQ(1u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV3->user_begin());
+
+  // Replace operand 1 (VPV2) with VPV3.
+  I1->setOperand(1, VPV3);
+  EXPECT_EQ(0u, VPV1->getNumUsers());
+  EXPECT_EQ(0u, VPV2->getNumUsers());
+  EXPECT_EQ(2u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV3->user_begin());
+  EXPECT_EQ(I1, *std::next(VPV3->user_begin()));
+
+  // Replace operand 0 (VPV3) with VPV4.
+  VPValue *VPV4 = new VPValue();
+  I1->setOperand(0, VPV4);
+  EXPECT_EQ(1u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV3->user_begin());
+  EXPECT_EQ(I1, *VPV4->user_begin());
+
+  // Replace operand 1 (VPV3) with VPV4.
+  I1->setOperand(1, VPV4);
+  EXPECT_EQ(0u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV4->user_begin());
+  EXPECT_EQ(I1, *std::next(VPV4->user_begin()));
+
+  delete I1;
+  delete VPV1;
+  delete VPV2;
+  delete VPV3;
+  delete VPV4;
+}
+
+TEST(VPInstructionTest, replaceAllUsesWith) {
+  VPValue *VPV1 = new VPValue();
+  VPValue *VPV2 = new VPValue();
+  VPInstruction *I1 = new VPInstruction(0, {VPV1, VPV2});
+
+  // Replace all uses of VPV1 with VPV3.
+  VPValue *VPV3 = new VPValue();
+  VPV1->replaceAllUsesWith(VPV3);
+  EXPECT_EQ(VPV3, I1->getOperand(0));
+  EXPECT_EQ(VPV2, I1->getOperand(1));
+  EXPECT_EQ(0u, VPV1->getNumUsers());
+  EXPECT_EQ(1u, VPV2->getNumUsers());
+  EXPECT_EQ(I1, *VPV2->user_begin());
+  EXPECT_EQ(1u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV3->user_begin());
+
+  // Replace all uses of VPV2 with VPV3.
+  VPV2->replaceAllUsesWith(VPV3);
+  EXPECT_EQ(VPV3, I1->getOperand(0));
+  EXPECT_EQ(VPV3, I1->getOperand(1));
+  EXPECT_EQ(0u, VPV1->getNumUsers());
+  EXPECT_EQ(0u, VPV2->getNumUsers());
+  EXPECT_EQ(2u, VPV3->getNumUsers());
+  EXPECT_EQ(I1, *VPV3->user_begin());
+
+  // Replace all uses of VPV3 with VPV1.
+  VPV3->replaceAllUsesWith(VPV1);
+  EXPECT_EQ(VPV1, I1->getOperand(0));
+  EXPECT_EQ(VPV1, I1->getOperand(1));
+  EXPECT_EQ(2u, VPV1->getNumUsers());
+  EXPECT_EQ(I1, *VPV1->user_begin());
+  EXPECT_EQ(0u, VPV2->getNumUsers());
+  EXPECT_EQ(0u, VPV3->getNumUsers());
+
+  delete I1;
+  delete VPV1;
+  delete VPV2;
+  delete VPV3;
+}
+
 TEST(VPBasicBlockTest, getPlan) {
   {
     VPBasicBlock *VPBB1 = new VPBasicBlock();