From 5e1e59180e7b9ac478208bacdaa129a5fa539a4f Mon Sep 17 00:00:00 2001
From: Keno Fischer <keno@alumni.harvard.edu>
Date: Wed, 15 Feb 2017 21:42:42 +0000
Subject: [PATCH] [GlobalObject] Fix setSection("")

Summary:
In rL291613, the section name was interned in LLVMContext. However,
this broke the ability to remove the section from a GlobalObject,
because it tried to intern empty strings, which is not allowed.
Fix that and add an appropriate regression test.

Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D29795

llvm-svn: 295238
---
 llvm/lib/IR/Globals.cpp            |  4 +++-
 llvm/unittests/IR/FunctionTest.cpp | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
index 6f7356524d38..675c515b21f4 100644
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -177,7 +177,9 @@ void GlobalObject::setSection(StringRef S) {
 
   // Get or create a stable section name string and put it in the table in the
   // context.
-  S = getContext().pImpl->SectionStrings.insert(S).first->first();
+  if (!S.empty()) {
+    S = getContext().pImpl->SectionStrings.insert(S).first->first();
+  }
   getContext().pImpl->GlobalObjectSections[this] = S;
 
   // Update the HasSectionHashEntryBit. Setting the section to the empty string
diff --git a/llvm/unittests/IR/FunctionTest.cpp b/llvm/unittests/IR/FunctionTest.cpp
index fb458597c37a..6838d7e2527f 100644
--- a/llvm/unittests/IR/FunctionTest.cpp
+++ b/llvm/unittests/IR/FunctionTest.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
 #include "gtest/gtest.h"
 using namespace llvm;
 
@@ -109,4 +110,24 @@ TEST(FunctionTest, stealArgumentListFrom) {
   EXPECT_TRUE(F2->hasLazyArguments());
 }
 
+// Test setting and removing section information
+TEST(FunctionTest, setSection) {
+  LLVMContext C;
+  Module M("test", C);
+
+  llvm::Function *F =
+      Function::Create(llvm::FunctionType::get(llvm::Type::getVoidTy(C), false),
+                       llvm::GlobalValue::ExternalLinkage, "F", &M);
+
+  F->setSection(".text.test");
+  EXPECT_TRUE(F->getSection() == ".text.test");
+  EXPECT_TRUE(F->hasSection());
+  F->setSection("");
+  EXPECT_FALSE(F->hasSection());
+  F->setSection(".text.test");
+  F->setSection(".text.test2");
+  EXPECT_TRUE(F->getSection() == ".text.test2");
+  EXPECT_TRUE(F->hasSection());
+}
+
 } // end namespace