[InstCombine] use 'match' to simplify code; NFC

llvm-svn: 344855

1 files changed, 56 insertions, 59 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index 0c8d64bff43..75f77779ab7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -876,65 +876,62 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
   if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
     replaceInstUsesWith(IE, VecOp);
 
-  // If the inserted element was extracted from some other vector, and if the
-  // indexes are constant, try to turn this into a shufflevector operation.
-  if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
-    if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp)) {
-      unsigned NumInsertVectorElts = IE.getType()->getNumElements();
-      unsigned NumExtractVectorElts =
-          EI->getOperand(0)->getType()->getVectorNumElements();
-      unsigned ExtractedIdx =
-        cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
-      unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
-      if (ExtractedIdx >= NumExtractVectorElts) // Out of range extract.
-        return replaceInstUsesWith(IE, VecOp);
-
-      if (InsertedIdx >= NumInsertVectorElts)  // Out of range insert.
-        return replaceInstUsesWith(IE, UndefValue::get(IE.getType()));
-
-      // If we are extracting a value from a vector, then inserting it right
-      // back into the same place, just use the input vector.
-      if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
-        return replaceInstUsesWith(IE, VecOp);
-
-      // TODO: Looking at the user(s) to determine if this insert is a
-      // fold-to-shuffle opportunity does not match the usual instcombine
-      // constraints. We should decide if the transform is worthy based only
-      // on this instruction and its operands, but that may not work currently.
-      //
-      // Here, we are trying to avoid creating shuffles before reaching
-      // the end of a chain of extract-insert pairs. This is complicated because
-      // we do not generally form arbitrary shuffle masks in instcombine
-      // (because those may codegen poorly), but collectShuffleElements() does
-      // exactly that.
-      //
-      // The rules for determining what is an acceptable target-independent
-      // shuffle mask are fuzzy because they evolve based on the backend's
-      // capabilities and real-world impact.
-      auto isShuffleRootCandidate = [](InsertElementInst &Insert) {
-        if (!Insert.hasOneUse())
-          return true;
-        auto *InsertUser = dyn_cast<InsertElementInst>(Insert.user_back());
-        if (!InsertUser)
-          return true;
-        return false;
-      };
-
-      // Try to form a shuffle from a chain of extract-insert ops.
-      if (isShuffleRootCandidate(IE)) {
-        SmallVector<Constant*, 16> Mask;
-        ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this);
-
-        // The proposed shuffle may be trivial, in which case we shouldn't
-        // perform the combine.
-        if (LR.first != &IE && LR.second != &IE) {
-          // We now have a shuffle of LHS, RHS, Mask.
-          if (LR.second == nullptr)
-            LR.second = UndefValue::get(LR.first->getType());
-          return new ShuffleVectorInst(LR.first, LR.second,
-                                       ConstantVector::get(Mask));
-        }
+  // If the inserted element was extracted from some other vector and both
+  // indexes are constant, try to turn this into a shuffle.
+  uint64_t InsertedIdx, ExtractedIdx;
+  Value *ExtVecOp;
+  if (match(IdxOp, m_ConstantInt(InsertedIdx)) &&
+      match(ScalarOp, m_ExtractElement(m_Value(ExtVecOp),
+                                       m_ConstantInt(ExtractedIdx)))) {
+    unsigned NumInsertVectorElts = IE.getType()->getNumElements();
+    unsigned NumExtractVectorElts = ExtVecOp->getType()->getVectorNumElements();
+    if (ExtractedIdx >= NumExtractVectorElts) // Out of range extract.
+      return replaceInstUsesWith(IE, VecOp);
+
+    if (InsertedIdx >= NumInsertVectorElts)  // Out of range insert.
+      return replaceInstUsesWith(IE, UndefValue::get(IE.getType()));
+
+    // If we are extracting a value from a vector, then inserting it right
+    // back into the same place, just use the input vector.
+    if (ExtVecOp == VecOp && ExtractedIdx == InsertedIdx)
+      return replaceInstUsesWith(IE, VecOp);
+
+    // TODO: Looking at the user(s) to determine if this insert is a
+    // fold-to-shuffle opportunity does not match the usual instcombine
+    // constraints. We should decide if the transform is worthy based only
+    // on this instruction and its operands, but that may not work currently.
+    //
+    // Here, we are trying to avoid creating shuffles before reaching
+    // the end of a chain of extract-insert pairs. This is complicated because
+    // we do not generally form arbitrary shuffle masks in instcombine
+    // (because those may codegen poorly), but collectShuffleElements() does
+    // exactly that.
+    //
+    // The rules for determining what is an acceptable target-independent
+    // shuffle mask are fuzzy because they evolve based on the backend's
+    // capabilities and real-world impact.
+    auto isShuffleRootCandidate = [](InsertElementInst &Insert) {
+      if (!Insert.hasOneUse())
+        return true;
+      auto *InsertUser = dyn_cast<InsertElementInst>(Insert.user_back());
+      if (!InsertUser)
+        return true;
+      return false;
+    };
+
+    // Try to form a shuffle from a chain of extract-insert ops.
+    if (isShuffleRootCandidate(IE)) {
+      SmallVector<Constant*, 16> Mask;
+      ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this);
+
+      // The proposed shuffle may be trivial, in which case we shouldn't
+      // perform the combine.
+      if (LR.first != &IE && LR.second != &IE) {
+        // We now have a shuffle of LHS, RHS, Mask.
+        if (LR.second == nullptr)
+          LR.second = UndefValue::get(LR.first->getType());
+        return new ShuffleVectorInst(LR.first, LR.second,
+                                     ConstantVector::get(Mask));
       }
     }
   }