Missing optimization assignment: Get Sibling node in a 1 indexed binary heap (llvm#47)

* Test Remote Change

* Implementation

* Add test cases

* Fix possible PR comments

* Fix PR comments

Author: Suraj-Yadav

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -5060,6 +5060,46 @@ void cs6475_debug(std::string DbgString) {
     dbgs() << DbgString;
 }
 
+Instruction *cs6475_optimizer_suraj(Instruction *I) {
+  // Converts
+  // if x is even, return x+1 else return x-1
+  // to
+  // return x^1
+
+  Value *INPUT, *A, *B, *C;
+  ConstantInt *CI = nullptr;
+
+  if (!match(I, m_c_Add(m_Value(C), m_Value(INPUT)))) {
+    return nullptr;
+  }
+  cs6475_debug("Add Expression Matched\n");
+
+  if (!(match(C, m_Select(m_Value(B), m_One(), m_ConstantInt(CI))) &&
+        CI->isMinusOne())) {
+    return nullptr;
+  }
+  cs6475_debug("Select Expression Matched\n");
+
+  if (!match(B, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(A), m_ZeroInt()))) {
+    return nullptr;
+  }
+  cs6475_debug("Compare Expression Matched\n");
+
+  if (!match(A, m_And(m_Specific(INPUT), m_One()))) {
+    return nullptr;
+  }
+  cs6475_debug("And Expression Matched\n");
+
+  cs6475_debug("Suraj: Optimization Possible\n");
+  auto Bitwidth = A->getType()->getIntegerBitWidth();
+  auto One = APInt(Bitwidth, 1);
+
+  log_optzn("Suraj Yadav");
+
+  auto *OptIns =
+      BinaryOperator::CreateXor(INPUT, ConstantInt::get(I->getContext(), One));
+  return OptIns;
+}
 
 Instruction *cs6475_optimizer_tavakkoli(Instruction *I) {
   cs6475_debug("\nCS 6475 matcher: running now\n");
@@ -5159,6 +5199,15 @@ Instruction* cs6475_optimizer(Instruction *I, InstCombinerImpl &IC, LazyValueInf
   }
   // END JOHN REGEHR
 
+  // BEGIN SURAJ YADAV
+  {
+    auto *NewI = cs6475_optimizer_suraj(I);
+    if (NewI != nullptr) {
+      return NewI;
+    }
+  }
+  // END SURAJ YADAV
+
   // BEGIN ASHTON WIERSDORF
   // x : float; c1, c2 are literal constants
   // x * x + c1 > c2 && c1 > c2 ⇒ is_nan(x)

llvm/test/Transforms/InstCombine/binary-heap-sibling-node-to-xor.ll

@@ -0,0 +1,52 @@
+; RUN: opt -O2 -S < %s | FileCheck %s
+
+; Positive Tests
+define i4 @sibling-node-i4(i4 %0) {
+; CHECK-LABEL: @sibling-node-i4(
+; CHECK:       [[d:%.+]] = xor i4 %0, 1
+; CHECK-NEXT:  ret i4 [[d]]
+;
+  %a = urem i4 %0, 2
+  %b = icmp eq i4 %a, 1
+  br i1 %b, label %right,label %left
+  left:
+  %c = add i4 %0, 1
+  ret i4 %c
+  right:
+  %d = sub i4 %0, 1
+  ret i4 %d
+}
+
+
+define i16 @sibling-node-i16(i16 %0) {
+; CHECK-LABEL: @sibling-node-i16(
+; CHECK:       [[d:%.+]] = xor i16 %0, 1
+; CHECK-NEXT:  ret i16 [[d]]
+;
+  %a = and i16 %0, 1
+  %b = icmp eq i16 %a, 0
+  %c = select i1 %b, i16 1, i16 -1
+  %d = add i16 %c, %0
+  ret i16 %d
+}
+
+
+; Negative Tests
+define i8 @sibling-node-i8-fail(i8 %0) {
+; CHECK-LABEL: @sibling-node-i8-fail(
+; CHECK:      [[a:%.+]] = and i8 %0, 1
+; CHECK-NEXT: [[b:%.+]] = icmp eq i8 [[a]], 0
+; CHECK-NEXT: [[c:%.+]] = select i1 [[b]], i8 -1, i8 1
+; CHECK-NEXT: [[d:%.+]] = add i8 [[c]], %0
+; CHECK-NEXT: ret i8 [[d]]
+;
+  %a = urem i8 %0, 2
+  %b = icmp eq i8 %a, 1
+  br i1 %b, label %right,label %left
+  left:
+  %c = sub i8 %0, 1
+  ret i8 %c
+  right:
+  %d = add i8 %0, 1
+  ret i8 %d
+}