From be73ba8c825816888abf1919a63afee218a63bbf Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Tue, 10 Nov 2015 09:47:48 +0000
Subject: [PATCH] Inliner: Do zero-cost inlines even if above a negative
 threshold (PR24851)

Differential Revision: http://reviews.llvm.org/D14499

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252595 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/InlineCost.cpp         |  2 +-
 test/Transforms/Inline/zero-cost.ll | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/Inline/zero-cost.ll

diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index 8169ce48246..26f2e7ff504 100644
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -1296,7 +1296,7 @@ bool CallAnalyzer::analyzeCall(CallSite CS) {
   else if (NumVectorInstructions <= NumInstructions / 2)
     Threshold -= (FiftyPercentVectorBonus - TenPercentVectorBonus);
 
-  return Cost < Threshold;
+  return Cost <= std::max(0, Threshold);
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
diff --git a/test/Transforms/Inline/zero-cost.ll b/test/Transforms/Inline/zero-cost.ll
new file mode 100644
index 00000000000..8e7194a1963
--- /dev/null
+++ b/test/Transforms/Inline/zero-cost.ll
@@ -0,0 +1,17 @@
+; RUN: opt -inline -S %s | FileCheck %s
+
+define void @f() {
+entry:
+  tail call void @g()
+  unreachable
+
+; CHECK-LABEL: @f
+; CHECK-NOT: call
+; CHECK: unreachable
+}
+
+define void @g() {
+entry:
+  unreachable
+}
+