From 42c9fd02c2e5f782133f6f340344b150b53c927f Mon Sep 17 00:00:00 2001
From: Mikael Holmen <mikael.holmen@ericsson.com>
Date: Tue, 3 Oct 2017 06:03:49 +0000
Subject: [PATCH] [Lint] Avoid failed assertion by fetching the proper pointer
 type

Summary:
When checking if a constant expression is a noop cast we fetched the
IntPtrType by doing DL->getIntPtrType(V->getType())). However, there can
be cases where V doesn't return a pointer, and then getIntPtrType()
triggers an assertion.

Now we pass DataLayout to isNoopCast so the method itself can determine
what the IntPtrType is.

Reviewers: arsenm

Reviewed By: arsenm

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D37894

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314763 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/IR/InstrTypes.h                  |  8 ++++++
 lib/Analysis/Lint.cpp                         |  2 +-
 lib/IR/Instructions.cpp                       | 28 ++++++++++++-------
 .../Lint/noop-cast-expr-no-pointer.ll         | 23 +++++++++++++++
 4 files changed, 50 insertions(+), 11 deletions(-)
 create mode 100644 test/Analysis/Lint/noop-cast-expr-no-pointer.ll

diff --git a/include/llvm/IR/InstrTypes.h b/include/llvm/IR/InstrTypes.h
index d749077fd34..59a71e5098f 100644
--- a/include/llvm/IR/InstrTypes.h
+++ b/include/llvm/IR/InstrTypes.h
@@ -789,6 +789,14 @@ public:
     Type *IntPtrTy ///< Integer type corresponding to Ptr types
   );
 
+  /// @brief Determine if the described cast is a no-op cast.
+  static bool isNoopCast(
+    Instruction::CastOps Opcode, ///< Opcode of cast
+    Type *SrcTy,         ///< SrcTy of cast
+    Type *DstTy,         ///< DstTy of cast
+    const DataLayout &DL ///< DataLayout to get the Int Ptr type from.
+  );
+
   /// @brief Determine if this cast is a no-op cast.
   bool isNoopCast(
     Type *IntPtrTy ///< Integer type corresponding to pointer
diff --git a/lib/Analysis/Lint.cpp b/lib/Analysis/Lint.cpp
index ada600a69b8..ae92f502f5c 100644
--- a/lib/Analysis/Lint.cpp
+++ b/lib/Analysis/Lint.cpp
@@ -683,7 +683,7 @@ Value *Lint::findValueImpl(Value *V, bool OffsetOk,
     if (Instruction::isCast(CE->getOpcode())) {
       if (CastInst::isNoopCast(Instruction::CastOps(CE->getOpcode()),
                                CE->getOperand(0)->getType(), CE->getType(),
-                               DL->getIntPtrType(V->getType())))
+                               *DL))
         return findValueImpl(CE->getOperand(0), OffsetOk, Visited);
     } else if (CE->getOpcode() == Instruction::ExtractValue) {
       ArrayRef<unsigned> Indices = CE->getIndices();
diff --git a/lib/IR/Instructions.cpp b/lib/IR/Instructions.cpp
index 2c49564e328..d6297cb6cae 100644
--- a/lib/IR/Instructions.cpp
+++ b/lib/IR/Instructions.cpp
@@ -2325,22 +2325,30 @@ bool CastInst::isNoopCast(Instruction::CastOps Opcode,
   }
 }
 
+/// @brief Determine if a cast is a no-op.
+bool CastInst::isNoopCast(Instruction::CastOps Opcode,
+                          Type *SrcTy,
+                          Type *DestTy,
+                          const DataLayout &DL) {
+  Type *PtrOpTy = nullptr;
+  if (Opcode == Instruction::PtrToInt)
+    PtrOpTy = SrcTy;
+  else if (Opcode == Instruction::IntToPtr)
+    PtrOpTy = DestTy;
+
+  Type *IntPtrTy = PtrOpTy ? DL.getIntPtrType(PtrOpTy) :
+                             DL.getIntPtrType(SrcTy->getContext(), 0);
+
+  return isNoopCast(Opcode, SrcTy, DestTy, IntPtrTy);
+}
+
 /// @brief Determine if a cast is a no-op.
 bool CastInst::isNoopCast(Type *IntPtrTy) const {
   return isNoopCast(getOpcode(), getOperand(0)->getType(), getType(), IntPtrTy);
 }
 
 bool CastInst::isNoopCast(const DataLayout &DL) const {
-  Type *PtrOpTy = nullptr;
-  if (getOpcode() == Instruction::PtrToInt)
-    PtrOpTy = getOperand(0)->getType();
-  else if (getOpcode() == Instruction::IntToPtr)
-    PtrOpTy = getType();
-
-  Type *IntPtrTy =
-      PtrOpTy ? DL.getIntPtrType(PtrOpTy) : DL.getIntPtrType(getContext(), 0);
-
-  return isNoopCast(getOpcode(), getOperand(0)->getType(), getType(), IntPtrTy);
+  return isNoopCast(getOpcode(), getOperand(0)->getType(), getType(), DL);
 }
 
 /// This function determines if a pair of casts can be eliminated and what
diff --git a/test/Analysis/Lint/noop-cast-expr-no-pointer.ll b/test/Analysis/Lint/noop-cast-expr-no-pointer.ll
new file mode 100644
index 00000000000..b9258711428
--- /dev/null
+++ b/test/Analysis/Lint/noop-cast-expr-no-pointer.ll
@@ -0,0 +1,23 @@
+; RUN: opt -lint < %s
+
+; lint shouldn't crash on any of the below functions
+
+@g_1 = external global [3 x i32]
+@g_2 = external global [2 x i32]
+
+define void @test1() {
+entry:
+  tail call void @f1(i16 zext (i1 icmp eq (i32* getelementptr inbounds ([2 x i32], [2 x i32]* @g_2, i64 0, i64 0), i32* getelementptr inbounds ([3 x i32], [3 x i32]* @g_1, i64 0, i64 1)) to i16))
+  ret void
+}
+
+declare void @f1(i16)
+
+define void @test2() {
+  tail call void inttoptr (i64 sext (i32 ptrtoint (void ()* @f2 to i32) to i64) to void ()*)()
+
+  ret void
+}
+
+declare void @f2()
+
-- 
2.40.0