[llvm] 3656558 - [Hexagon] Only allow single HVX vector loads/stores in lowering

[Krzysztof Parzyszek via llvm-commits]

Author: Krzysztof Parzyszek
Date: 2020-03-14T14:26:01-05:00
New Revision: 3656558cecafd458ae63a5ef70758832f239b26d

URL: https://github.com/llvm/llvm-project/commit/3656558cecafd458ae63a5ef70758832f239b26d
DIFF: https://github.com/llvm/llvm-project/commit/3656558cecafd458ae63a5ef70758832f239b26d.diff

LOG: [Hexagon] Only allow single HVX vector loads/stores in lowering

This will prevent store widening from forming vector pair stores,
which eventually end up broken up into single stores.

Added: 
    

Modified: 
    llvm/lib/Target/Hexagon/HexagonISelLoweringHVX.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/Hexagon/HexagonISelLoweringHVX.cpp b/llvm/lib/Target/Hexagon/HexagonISelLoweringHVX.cpp
index 5ab000df2db0..0242bfcea7de 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLoweringHVX.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLoweringHVX.cpp
@@ -304,6 +304,10 @@ HexagonTargetLowering::allowsHvxMemoryAccess(MVT VecTy, unsigned Alignment,
         MachineMemOperand::Flags Flags, bool *Fast) const {
   // Bool vectors are excluded by default, but make it explicit to
   // emphasize that bool vectors cannot be loaded or stored.
+  // Also, disallow double vector stores (to prevent unnecessary
+  // store widening in DAG combiner).
+  if (VecTy.getSizeInBits() > 8*Subtarget.getVectorLength())
+    return false;
   if (!Subtarget.isHVXVectorType(VecTy, /*IncludeBool=*/false))
     return false;
   if (Fast)