[PATCH] D77442: [SVE] Take constant fold fast path for splatted vscale vectors

[Christopher Tetreault via Phabricator via llvm-commits]

ctetreau created this revision.
Herald added subscribers: llvm-commits, psnobl, rkruppe, hiraditya, tschuett.
Herald added a reviewer: efriedma.
Herald added a project: LLVM.

- This should be a perfectly reasonable operation for scalable vectors


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77442

Files:
  llvm/lib/IR/ConstantFold.cpp


Index: llvm/lib/IR/ConstantFold.cpp
===================================================================
--- llvm/lib/IR/ConstantFold.cpp
+++ llvm/lib/IR/ConstantFold.cpp
@@ -2009,11 +2009,6 @@
     }
   } else if (auto *C1VTy = dyn_cast<VectorType>(C1->getType())) {
 
-    // Do not iterate on scalable vector. The number of elements is unknown at
-    // compile-time.
-    if (C1VTy->isScalable())
-      return nullptr;
-
     // Fast path for splatted constants.
     if (Constant *C1Splat = C1->getSplatValue())
       if (Constant *C2Splat = C2->getSplatValue())
@@ -2021,6 +2016,11 @@
             C1VTy->getElementCount(),
             ConstantExpr::getCompare(pred, C1Splat, C2Splat));
 
+    // Do not iterate on scalable vector. The number of elements is unknown at
+    // compile-time.
+    if (C1VTy->isScalable())
+      return nullptr;
+
     // If we can constant fold the comparison of each element, constant fold
     // the whole vector comparison.
     SmallVector<Constant*, 4> ResElts;


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