From 92f3d29af0c0f2c98ba0dfacac00bbb6eb1f741d Mon Sep 17 00:00:00 2001
From: Paul Walker <paul.walker@arm.com>
Date: Thu, 28 May 2020 10:21:27 +0000
Subject: [PATCH] [SelectionDAG] Update getNode asserts for
 EXTRACT/INSERT_SUBVECTOR.

Summary:
The description of EXTACT_SUBVECTOR and INSERT_SUBVECTOR has been
changed to accommodate scalable vectors (see ISDOpcodes.h). This
patch updates the asserts used to verify these requirements when
using SelectionDAG's getNode interface.

This patch introduces the MVT function getVectorMinNumElements
that can be used against fixed-length and scalable vectors when
only the known minimum vector length is required.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80709
---
 llvm/include/llvm/CodeGen/ValueTypes.h         |  5 +++
 llvm/include/llvm/Support/MachineValueType.h   |  5 +++
 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 42 +++++++++++++++-----------
 3 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/ValueTypes.h b/llvm/include/llvm/CodeGen/ValueTypes.h
index 15a4bfe..c6f8a81 100644
--- a/llvm/include/llvm/CodeGen/ValueTypes.h
+++ b/llvm/include/llvm/CodeGen/ValueTypes.h
@@ -292,6 +292,11 @@ namespace llvm {
       return {getExtendedVectorNumElements(), isExtendedScalableVector()};
     }
 
+    /// Given a vector type, return the minimum number of elements it contains.
+    unsigned getVectorMinNumElements() const {
+      return getVectorElementCount().Min;
+    }
+
     /// Return the size of the specified value type in bits.
     ///
     /// If the value type is a scalable vector type, the scalable property will
diff --git a/llvm/include/llvm/Support/MachineValueType.h b/llvm/include/llvm/Support/MachineValueType.h
index 93683eb..9d2d0c8 100644
--- a/llvm/include/llvm/Support/MachineValueType.h
+++ b/llvm/include/llvm/Support/MachineValueType.h
@@ -706,6 +706,11 @@ namespace llvm {
       return { getVectorNumElements(), isScalableVector() };
     }
 
+    /// Given a vector type, return the minimum number of elements it contains.
+    unsigned getVectorMinNumElements() const {
+      return getVectorElementCount().Min;
+    }
+
     /// Returns the size of the specified MVT in bits.
     ///
     /// If the value type is a scalable vector type, the scalable property will
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index bd1a5a4..0a108c9 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5461,21 +5461,24 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     }
     break;
   case ISD::EXTRACT_SUBVECTOR:
-    assert(VT.isVector() && N1.getValueType().isVector() &&
-           "Extract subvector VTs must be a vectors!");
-    assert(VT.getVectorElementType() ==
-               N1.getValueType().getVectorElementType() &&
+    EVT N1VT = N1.getValueType();
+    assert(VT.isVector() && N1VT.isVector() &&
+           "Extract subvector VTs must be vectors!");
+    assert(VT.getVectorElementType() == N1VT.getVectorElementType() &&
            "Extract subvector VTs must have the same element type!");
-    assert(VT.getVectorNumElements() <=
-               N1.getValueType().getVectorNumElements() &&
+    assert((VT.isFixedLengthVector() || N1VT.isScalableVector()) &&
+           "Cannot extract a scalable vector from a fixed length vector!");
+    assert((VT.isScalableVector() != N1VT.isScalableVector() ||
+            VT.getVectorMinNumElements() <= N1VT.getVectorMinNumElements()) &&
            "Extract subvector must be from larger vector to smaller vector!");
     assert(N2C && "Extract subvector index must be a constant");
-    assert(VT.getVectorNumElements() + N2C->getZExtValue() <=
-               N1.getValueType().getVectorNumElements() &&
+    assert((VT.isScalableVector() != N1VT.isScalableVector() ||
+            (VT.getVectorMinNumElements() + N2C->getZExtValue()) <=
+                N1VT.getVectorMinNumElements()) &&
            "Extract subvector overflow!");
 
     // Trivial extraction.
-    if (VT == N1.getValueType())
+    if (VT == N1VT)
       return N1;
 
     // EXTRACT_SUBVECTOR of an UNDEF is an UNDEF.
@@ -5665,22 +5668,27 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     // Inserting undef into undef is still undef.
     if (N1.isUndef() && N2.isUndef())
       return getUNDEF(VT);
-    assert(VT.isVector() && N1.getValueType().isVector() &&
-           N2.getValueType().isVector() &&
-           "Insert subvector VTs must be a vectors");
+
+    EVT N2VT = N2.getValueType();
     assert(VT == N1.getValueType() &&
            "Dest and insert subvector source types must match!");
-    assert(N2.getSimpleValueType() <= N1.getSimpleValueType() &&
+    assert(VT.isVector() && N2VT.isVector() &&
+           "Insert subvector VTs must be vectors!");
+    assert((VT.isScalableVector() || N2VT.isFixedLengthVector()) &&
+           "Cannot insert a scalable vector into a fixed length vector!");
+    assert((VT.isScalableVector() != N2VT.isScalableVector() ||
+            VT.getVectorMinNumElements() >= N2VT.getVectorMinNumElements()) &&
            "Insert subvector must be from smaller vector to larger vector!");
     assert(isa<ConstantSDNode>(N3) &&
            "Insert subvector index must be constant");
-    assert(N2.getValueType().getVectorNumElements() +
-                   cast<ConstantSDNode>(N3)->getZExtValue() <=
-               VT.getVectorNumElements() &&
+    assert((VT.isScalableVector() != N2VT.isScalableVector() ||
+            (N2VT.getVectorMinNumElements() +
+             cast<ConstantSDNode>(N3)->getZExtValue()) <=
+                VT.getVectorMinNumElements()) &&
            "Insert subvector overflow!");
 
     // Trivial insertion.
-    if (VT == N2.getValueType())
+    if (VT == N2VT)
       return N2;
 
     // If this is an insert of an extracted vector into an undef vector, we
-- 
2.7.4