From 043733d677310d6b0ac465b938e82733a9f4cfce Mon Sep 17 00:00:00 2001
From: hyeongyu kim <gusrb406@snu.ac.kr>
Date: Tue, 21 Sep 2021 21:48:04 +0900
Subject: [PATCH] [IR] Add the constructor of ShuffleVector for
 one-input-vector.

One of the two inputs of the Shufflevector is often a placeholder.
Previously, there were cases where the placeholder was undef, and there were cases where it was poison.
I added these constructors to create a placeholder consistently.

Changing to use the newly added constructor will be written in a separate patch.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D110146
---
 llvm/include/llvm/IR/Instructions.h |  8 ++++++++
 llvm/lib/IR/Instructions.cpp        | 26 ++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index fac6b108fd6a..c5d575d25627 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -2017,6 +2017,14 @@ protected:
   ShuffleVectorInst *cloneImpl() const;
 
 public:
+  ShuffleVectorInst(Value *V1, Value *Mask, const Twine &NameStr = "",
+                    Instruction *InsertBefore = nullptr);
+  ShuffleVectorInst(Value *V1, Value *Mask, const Twine &NameStr,
+                    BasicBlock *InsertAtEnd);
+  ShuffleVectorInst(Value *V1, ArrayRef<int> Mask, const Twine &NameStr = "",
+                    Instruction *InsertBefore = nullptr);
+  ShuffleVectorInst(Value *V1, ArrayRef<int> Mask, const Twine &NameStr,
+                    BasicBlock *InsertAtEnd);
   ShuffleVectorInst(Value *V1, Value *V2, Value *Mask,
                     const Twine &NameStr = "",
                     Instruction *InsertBefor = nullptr);
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 7b940fc95b6a..2ca68212fa10 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -1907,6 +1907,32 @@ bool InsertElementInst::isValidOperands(const Value *Vec, const Value *Elt,
 //                      ShuffleVectorInst Implementation
 //===----------------------------------------------------------------------===//
 
+static Value *createPlaceholderForShuffleVector(Value *V) {
+  assert(V && "Cannot create placeholder of nullptr V");
+  return PoisonValue::get(V->getType());
+}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *Mask, const Twine &Name,
+                                     Instruction *InsertBefore)
+    : ShuffleVectorInst(V1, createPlaceholderForShuffleVector(V1), Mask, Name,
+                        InsertBefore) {}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *Mask, const Twine &Name,
+                                     BasicBlock *InsertAtEnd)
+    : ShuffleVectorInst(V1, createPlaceholderForShuffleVector(V1), Mask, Name,
+                        InsertAtEnd) {}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, ArrayRef<int> Mask,
+                                     const Twine &Name,
+                                     Instruction *InsertBefore)
+    : ShuffleVectorInst(V1, createPlaceholderForShuffleVector(V1), Mask, Name,
+                        InsertBefore) {}
+
+ShuffleVectorInst::ShuffleVectorInst(Value *V1, ArrayRef<int> Mask,
+                                     const Twine &Name, BasicBlock *InsertAtEnd)
+    : ShuffleVectorInst(V1, createPlaceholderForShuffleVector(V1), Mask, Name,
+                        InsertAtEnd) {}
+
 ShuffleVectorInst::ShuffleVectorInst(Value *V1, Value *V2, Value *Mask,
                                      const Twine &Name,
                                      Instruction *InsertBefore)