From aa8be5aeead7ad894270aa025e7165169c1a54d2 Mon Sep 17 00:00:00 2001
From: Bjorn Pettersson <bjorn.a.pettersson@ericsson.com>
Date: Mon, 14 Sep 2020 22:53:54 +0200
Subject: [PATCH] [Scalarizer] Avoid changing name of non-instructions

The "takeName" logic in ScalarizerVisitor::gather did not consider
that the value vector could refer to non-instructions, such as
global variables. This patch make sure that we avoid changing the
name of a value if it isn't an instruction.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D87685
---
 llvm/lib/Transforms/Scalar/Scalarizer.cpp       |  3 ++-
 llvm/test/Transforms/Scalarizer/global-bug-2.ll | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/Transforms/Scalarizer/global-bug-2.ll

diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
index 3bc0cbd..c7fe21f 100644
--- a/llvm/lib/Transforms/Scalar/Scalarizer.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -398,7 +398,8 @@ void ScalarizerVisitor::gather(Instruction *Op, const ValueVector &CV) {
         continue;
 
       Instruction *Old = cast<Instruction>(V);
-      CV[I]->takeName(Old);
+      if (isa<Instruction>(CV[I]))
+        CV[I]->takeName(Old);
       Old->replaceAllUsesWith(CV[I]);
       PotentiallyDeadInstrs.emplace_back(Old);
     }
diff --git a/llvm/test/Transforms/Scalarizer/global-bug-2.ll b/llvm/test/Transforms/Scalarizer/global-bug-2.ll
new file mode 100644
index 0000000..60f61ab
--- /dev/null
+++ b/llvm/test/Transforms/Scalarizer/global-bug-2.ll
@@ -0,0 +1,20 @@
+; RUN: opt < %s -scalarizer -S -o - | FileCheck %s
+; RUN: opt < %s -passes='function(scalarizer)' -S | FileCheck %s
+
+; The scalarizer used to change the name of the global variable
+; Check that the we don't do that any longer.
+;
+; CHECK: @c.a = global i16 0, align 1
+
+@c.a = global i16 0, align 1
+
+define void @c() {
+entry:
+  br label %for.cond1
+
+for.cond1:                                        ; preds = %for.cond1, %entry
+  %d.sroa.0.0 = phi <4 x i16*> [ <i16* @c.a, i16* @c.a, i16* @c.a, i16* @c.a>, %entry ], [ %d.sroa.0.1.vec.insert, %for.cond1 ]
+  %d.sroa.0.0.vec.extract = extractelement <4 x i16*> %d.sroa.0.0, i32 0
+  %d.sroa.0.1.vec.insert = shufflevector <4 x i16*> <i16* @c.a, i16* null, i16* undef, i16* undef>, <4 x i16*> %d.sroa.0.0, <4 x i32> <i32 0, i32 1, i32 6, i32 7>
+  br label %for.cond1
+}
-- 
2.7.4