[llvm] [TailRecElim] Introduce support for shift accumulator optimization (PR #181331)

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git-clang-format --diff origin/main HEAD --extensions cpp -- llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp --diff_from_common_commit
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``````````diff
diff --git a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
index 51f1143de..5d77e422e 100644
--- a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -381,9 +381,9 @@ static bool canMoveAboveCall(Instruction *I, CallInst *CI, AliasAnalysis *AA) {
 // This relation applies to left shifts as well as arithmetic/logical right
 // shifts when the shift amount is a constant.
 static bool isPseudoAssociative(Instruction *I) {
-    if (!I->isShift())
-      return false;
-    return isa<ConstantInt>(I->getOperand(1));
+  if (!I->isShift())
+    return false;
+  return isa<ConstantInt>(I->getOperand(1));
 }
 
 // Find the base-case return value for function F: examine all
@@ -406,10 +406,10 @@ static Constant *getReturnValue(Function &F) {
   Constant *BaseCaseVal = nullptr;
 
   // Local lambda with conservative bail-out: It isn't so trivial to perform TRE
-  // if the return value depends on the result of a recursive call, because the return value will be different
-  // for different iterations of the recursion. So we ignore return values
-  // that depend on recursive calls.
-  auto TryGetConstantBaseCase = [&](Value *RV) -> Constant* {
+  // if the return value depends on the result of a recursive call, because the
+  // return value will be different for different iterations of the recursion.
+  // So we ignore return values that depend on recursive calls.
+  auto TryGetConstantBaseCase = [&](Value *RV) -> Constant * {
     // Case 1: direct constant return.
     if (auto *C = dyn_cast<Constant>(RV))
       return C;

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https://github.com/llvm/llvm-project/pull/181331