[NFC][SCEV] Reflow `getRelevantLoop()` into an exhaustive switch

1 files changed, 33 insertions, 16 deletions

diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index c027638..abb1496 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -678,16 +678,32 @@ const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
   if (!Pair.second)
     return Pair.first->second;
 
-  if (isa<SCEVConstant>(S))
-    // A constant has no relevant loops.
-    return nullptr;
-  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
-    if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
-      return Pair.first->second = SE.LI.getLoopFor(I->getParent());
-    // A non-instruction has no relevant loops.
-    return nullptr;
+  switch (S->getSCEVType()) {
+  case scConstant:
+    return nullptr; // A constant has no relevant loops.
+  case scTruncate:
+  case scZeroExtend:
+  case scSignExtend:
+  case scPtrToInt: {
+    const SCEVCastExpr *C = cast<SCEVCastExpr>(S);
+    const Loop *Result = getRelevantLoop(C->getOperand());
+    return RelevantLoops[C] = Result;
+  }
+  case scUDivExpr: {
+    const SCEVUDivExpr *D = cast<SCEVUDivExpr>(S);
+    const Loop *Result = PickMostRelevantLoop(
+        getRelevantLoop(D->getLHS()), getRelevantLoop(D->getRHS()), SE.DT);
+    return RelevantLoops[D] = Result;
   }
-  if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
+  case scAddExpr:
+  case scMulExpr:
+  case scAddRecExpr:
+  case scUMaxExpr:
+  case scSMaxExpr:
+  case scUMinExpr:
+  case scSMinExpr:
+  case scSequentialUMinExpr: {
+    const SCEVNAryExpr *N = cast<SCEVNAryExpr>(S);
     const Loop *L = nullptr;
     if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
       L = AR->getLoop();
@@ -695,14 +711,15 @@ const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
       L = PickMostRelevantLoop(L, getRelevantLoop(Op), SE.DT);
     return RelevantLoops[N] = L;
   }
-  if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
-    const Loop *Result = getRelevantLoop(C->getOperand());
-    return RelevantLoops[C] = Result;
+  case scUnknown: {
+    const SCEVUnknown *U = cast<SCEVUnknown>(S);
+    if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
+      return Pair.first->second = SE.LI.getLoopFor(I->getParent());
+    // A non-instruction has no relevant loops.
+    return nullptr;
   }
-  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
-    const Loop *Result = PickMostRelevantLoop(
-        getRelevantLoop(D->getLHS()), getRelevantLoop(D->getRHS()), SE.DT);
-    return RelevantLoops[D] = Result;
+  case scCouldNotCompute:
+    llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
   }
   llvm_unreachable("Unexpected SCEV type!");
 }