[Differential] D80116: [IR] Simplify Use::swap. NFCI.

[Jay Foad via llvm-commits]

This revision was not accepted when it landed; it landed in state "Needs Review".
This revision was automatically updated to reflect the committed changes.
Closed by commit rG5e5bda74b61b: [IR] Simplify Use::swap. NFCI. (authored by foad).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D80116/new/


  https://reviews.llvm.org/D80116

Files:
  llvm/lib/IR/Use.cpp
  llvm/test/Transforms/LoopReroll/nonconst_lb.ll



Index: llvm/test/Transforms/LoopReroll/nonconst_lb.ll
===================================================================
--- llvm/test/Transforms/LoopReroll/nonconst_lb.ll
+++ llvm/test/Transforms/LoopReroll/nonconst_lb.ll
@@ -48,7 +48,7 @@
   ret void
 }
 ; CHECK-LABEL: @foo
-; CHECK: for.body.preheader:                               ; preds = %entry
+; CHECK: for.body.preheader:
 ; CHECK:   %0 = add i32 %n, -1
 ; CHECK:   %1 = sub i32 %0, %m
 ; CHECK:   %2 = lshr i32 %1, 2
@@ -56,7 +56,7 @@
 ; CHECK:   %4 = add i32 %3, 3
 ; CHECK:   br label %for.body
 
-; CHECK: for.body:                                         ; preds = %for.body, %for.body.preheader
+; CHECK: for.body:
 ; CHECK:   %indvar = phi i32 [ 0, %for.body.preheader ], [ %indvar.next, %for.body ]
 ; CHECK:   %5 = add i32 %m, %indvar
 ; CHECK:   %arrayidx = getelementptr inbounds i32, i32* %B, i32 %5
Index: llvm/lib/IR/Use.cpp
===================================================================
--- llvm/lib/IR/Use.cpp
+++ llvm/lib/IR/Use.cpp
@@ -17,24 +17,17 @@
   if (Val == RHS.Val)
     return;
 
-  if (Val)
-    removeFromList();
-
-  Value *OldVal = Val;
-  if (RHS.Val) {
-    RHS.removeFromList();
-    Val = RHS.Val;
-    Val->addUse(*this);
-  } else {
-    Val = nullptr;
-  }
-
-  if (OldVal) {
-    RHS.Val = OldVal;
-    RHS.Val->addUse(RHS);
-  } else {
-    RHS.Val = nullptr;
-  }
+  std::swap(Val, RHS.Val);
+  std::swap(Next, RHS.Next);
+  std::swap(Prev, RHS.Prev);
+
+  *Prev = this;
+  if (Next)
+    Next->Prev = &Next;
+
+  *RHS.Prev = &RHS;
+  if (RHS.Next)
+    RHS.Next->Prev = &RHS.Next;
 }
 
 unsigned Use::getOperandNo() const {


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