From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Sat, 20 Jul 2013 23:33:15 +0000 (+0000)
Subject: Don't crash when llvm.compiler.used becomes empty.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=64f2f910bd48c123a6b5945ebe90b018f7bea4d5;p=oota-llvm.git

Don't crash when llvm.compiler.used becomes empty.

GlobalOpt simplifies llvm.compiler.used by removing any members that are also
in the more strict llvm.used. Handle the special case where llvm.compiler.used
becomes empty.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186778 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 669162cb3d8..183a599bc12 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -3070,6 +3070,11 @@ static int compareNames(const void *A, const void *B) {
 
 static void setUsedInitializer(GlobalVariable &V,
                                SmallPtrSet<GlobalValue *, 8> Init) {
+  if (Init.empty()) {
+    V.eraseFromParent();
+    return;
+  }
+
   SmallVector<llvm::Constant *, 8> UsedArray;
   PointerType *Int8PtrTy = Type::getInt8PtrTy(V.getContext());
 
diff --git a/test/Transforms/GlobalOpt/compiler-used.ll b/test/Transforms/GlobalOpt/compiler-used.ll
new file mode 100644
index 00000000000..a710d272edc
--- /dev/null
+++ b/test/Transforms/GlobalOpt/compiler-used.ll
@@ -0,0 +1,16 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+
+; Test that when all members of llvm.compiler.used are found to be redundant
+; we delete it instead of crashing.
+
+define void @foo() {
+  ret void
+}
+
+@llvm.used = appending global [1 x i8*] [i8* bitcast (void ()* @foo to i8*)], section "llvm.metadata"
+
+@llvm.compiler.used = appending global [1 x i8*] [i8* bitcast (void ()* @foo to i8*)], section "llvm.metadata"
+
+; CHECK-NOT: @llvm.compiler.used
+; CHECK: @llvm.used = appending global [1 x i8*] [i8* bitcast (void ()* @foo to i8*)], section "llvm.metadata"
+; CHECK-NOT: @llvm.compiler.used