Add getSVEVectorSizeInBits to query known SVE length

Author: rj-jesus

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

@@ -7385,14 +7385,13 @@ bool AArch64DAGToDAGISel::SelectAddrModeIndexedSVE(SDNode *Root, SDValue N,
     MulImm = cast<ConstantSDNode>(VScale.getOperand(0))->getSExtValue();
   } else if (auto C = dyn_cast<ConstantSDNode>(VScale)) {
     int64_t ByteOffset = C->getSExtValue();
-    constexpr auto SVEBitsPerBlock = AArch64::SVEBitsPerBlock;
-    auto MinVScale = Subtarget->getMinSVEVectorSizeInBits() / SVEBitsPerBlock;
-    auto MaxVScale = Subtarget->getMaxSVEVectorSizeInBits() / SVEBitsPerBlock;
+    const auto KnownVScale =
+        Subtarget->getSVEVectorSizeInBits() / AArch64::SVEBitsPerBlock;
 
-    if (!MaxVScale || MinVScale != MaxVScale || ByteOffset % MaxVScale != 0)
+    if (!KnownVScale || ByteOffset % KnownVScale != 0)
       return false;
 
-    MulImm = ByteOffset / MaxVScale;
+    MulImm = ByteOffset / KnownVScale;
   } else
     return false;
 

llvm/lib/Target/AArch64/AArch64Subtarget.h

@@ -391,7 +391,7 @@ class AArch64Subtarget final : public AArch64GenSubtargetInfo {
   void mirFileLoaded(MachineFunction &MF) const override;
 
   // Return the known range for the bit length of SVE data registers. A value
-  // of 0 means nothing is known about that particular limit beyong what's
+  // of 0 means nothing is known about that particular limit beyond what's
   // implied by the architecture.
   unsigned getMaxSVEVectorSizeInBits() const {
     assert(isSVEorStreamingSVEAvailable() &&
@@ -405,6 +405,17 @@ class AArch64Subtarget final : public AArch64GenSubtargetInfo {
     return MinSVEVectorSizeInBits;
   }
 
+  // Return the known bit length of SVE data registers. A value of 0 means the
+  // length is unkown beyond what's implied by the architecture.
+  unsigned getSVEVectorSizeInBits() const {
+    assert(isSVEorStreamingSVEAvailable() &&
+           "Tried to get SVE vector length without SVE support!");
+    if (MaxSVEVectorSizeInBits &&
+        MinSVEVectorSizeInBits == MaxSVEVectorSizeInBits)
+      return MaxSVEVectorSizeInBits;
+    return 0;
+  }
+
   bool useSVEForFixedLengthVectors() const {
     if (!isSVEorStreamingSVEAvailable())
       return false;