From 9cdc27ffac48acfc458d4d6ae9db1f90757645a1 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Sun, 31 May 2020 16:18:52 -0400
Subject: [PATCH] AArch64/GlobalISel: Fix assert on call returning 0 sized type

I don't know why this is considered valid IR, but it probably should
not be.
---
 .../llvm/CodeGen/GlobalISel/CallLowering.h    |  3 +-
 .../Target/AArch64/AArch64CallLowering.cpp    |  6 +--
 .../AArch64/GlobalISel/call-translator.ll     | 42 +++++++++++++++++++
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
index 439837760663..88a1837665aa 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -61,7 +61,8 @@ public:
       if (!Regs.empty() && Flags.empty())
         this->Flags.push_back(ISD::ArgFlagsTy());
       // FIXME: We should have just one way of saying "no register".
-      assert((Ty->isVoidTy() == (Regs.empty() || Regs[0] == 0)) &&
+      assert(((Ty->isVoidTy() || Ty->isEmptyTy()) ==
+              (Regs.empty() || Regs[0] == 0)) &&
              "only void types should have no register");
     }
 
diff --git a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
index f6daa5f7f9e2..9f37efc0951b 100644
--- a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
@@ -237,13 +237,13 @@ void AArch64CallLowering::splitToValueTypes(
   const AArch64TargetLowering &TLI = *getTLI<AArch64TargetLowering>();
   LLVMContext &Ctx = OrigArg.Ty->getContext();
 
-  if (OrigArg.Ty->isVoidTy())
-    return;
-
   SmallVector<EVT, 4> SplitVTs;
   SmallVector<uint64_t, 4> Offsets;
   ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitVTs, &Offsets, 0);
 
+  if (SplitVTs.size() == 0)
+    return;
+
   if (SplitVTs.size() == 1) {
     // No splitting to do, but we want to replace the original type (e.g. [1 x
     // double] -> double).
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/call-translator.ll b/llvm/test/CodeGen/AArch64/GlobalISel/call-translator.ll
index e60360fdee68..ad38b2bb8b9c 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/call-translator.ll
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/call-translator.ll
@@ -279,3 +279,45 @@ define void @take_split_struct([2 x i64]* %ptr, i64, i64, i64,
   store [2 x i64] %in, [2 x i64]* %ptr
   ret void
 }
+
+%size0type = type { }
+declare %size0type @func.returns.size0.struct()
+
+; CHECK-LABEL: name: call_returns_size0_struct
+; CHECK: bb.1
+; CHECK-NEXT: ADJCALLSTACKDOWN
+; CHECK-NEXT: BL
+; CHECK-NEXT: ADJCALLSTACKUP
+; CHECK-NEXT: RET_ReallyLR
+define void @call_returns_size0_struct() {
+  ; FIXME: Why is this valid IR?
+  %call = call %size0type @func.returns.size0.struct()
+  ret void
+}
+
+declare [0 x i8] @func.returns.size0.array()
+
+; CHECK-LABEL: name: call_returns_size0_array
+; CHECK: bb.1
+; CHECK-NEXT: ADJCALLSTACKDOWN
+; CHECK-NEXT: BL
+; CHECK-NEXT: ADJCALLSTACKUP
+; CHECK-NEXT: RET_ReallyLR
+define void @call_returns_size0_array() {
+  ; FIXME: Why is this valid IR?
+  %call = call [0 x i8] @func.returns.size0.array()
+  ret void
+}
+
+declare [1 x %size0type] @func.returns.array.size0.struct()
+; CHECK-LABEL: name: call_returns_array_size0_struct
+; CHECK: bb.1
+; CHECK-NEXT: ADJCALLSTACKDOWN
+; CHECK-NEXT: BL
+; CHECK-NEXT: ADJCALLSTACKUP
+; CHECK-NEXT: RET_ReallyLR
+define void @call_returns_array_size0_struct() {
+  ; FIXME: Why is this valid IR?
+  %call = call [1 x %size0type] @func.returns.array.size0.struct()
+  ret void
+}