[SVE][IR] Scalable Vector IR Type

* Adds a 'scalable' flag to VectorType
* Adds an 'ElementCount' class to VectorType to pass (possibly scalable) vector lengths, with overloaded operators.
* Modifies existing helper functions to use ElementCount
* Adds support for serializing/deserializing to/from both textual and bitcode IR formats
* Extends the verifier to reject global variables of scalable types
* Updates documentation

See the latest version of the RFC here: http://lists.llvm.org/pipermail/llvm-dev/2018-July/124396.html

Reviewers: rengolin, lattner, echristo, chandlerc, hfinkel, rkruppe, samparker, SjoerdMeijer, greened, sebpop

Reviewed By: hfinkel, sebpop

Differential Revision: https://reviews.llvm.org/D32530

llvm-svn: 361953

2 files changed, 8 insertions, 3 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index b23115ba31d..134ce036703 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1758,7 +1758,8 @@ Error BitcodeReader::parseTypeTableBody() {
         return error("Invalid type");
       ResultTy = ArrayType::get(ResultTy, Record[0]);
       break;
-    case bitc::TYPE_CODE_VECTOR:    // VECTOR: [numelts, eltty]
+    case bitc::TYPE_CODE_VECTOR:    // VECTOR: [numelts, eltty] or
+                                    //         [numelts, eltty, scalable]
       if (Record.size() < 2)
         return error("Invalid record");
       if (Record[0] == 0)
@@ -1766,7 +1767,8 @@ Error BitcodeReader::parseTypeTableBody() {
       ResultTy = getTypeByID(Record[1]);
       if (!ResultTy || !StructType::isValidElementType(ResultTy))
         return error("Invalid type");
-      ResultTy = VectorType::get(ResultTy, Record[0]);
+      bool Scalable = Record.size() > 2 ? Record[2] : false;
+      ResultTy = VectorType::get(ResultTy, Record[0], Scalable);
       break;
     }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 00d6fe8e27c..8e1e06226bb 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -931,10 +931,13 @@ void ModuleBitcodeWriter::writeTypeTable() {
     }
     case Type::VectorTyID: {
       VectorType *VT = cast<VectorType>(T);
-      // VECTOR [numelts, eltty]
+      // VECTOR [numelts, eltty] or
+      //        [numelts, eltty, scalable]
       Code = bitc::TYPE_CODE_VECTOR;
       TypeVals.push_back(VT->getNumElements());
       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
+      if (VT->isScalable())
+        TypeVals.push_back(VT->isScalable());
       break;
     }
     }