From: Jessica Paquette <jpaquette@apple.com>
Date: Mon, 14 Aug 2017 22:57:41 +0000 (+0000)
Subject: [MachineOutliner] Only outline candidates of length >= 2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=af163855d63adf28aa0e8062d940a6f969a514df;p=llvm

[MachineOutliner] Only outline candidates of length >= 2

Since we don't factor in instruction lengths into outlining calculations
right now, it's never the case that a candidate could have length < 2.

Thus, we should quit early when we see such candidates.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310894 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MachineOutliner.cpp b/lib/CodeGen/MachineOutliner.cpp
index 36163538f4e..9a8eebff2b5 100644
--- a/lib/CodeGen/MachineOutliner.cpp
+++ b/lib/CodeGen/MachineOutliner.cpp
@@ -844,6 +844,13 @@ MachineOutliner::findCandidates(SuffixTree &ST, const TargetInstrInfo &TII,
 
     // Figure out if this candidate is beneficial.
     size_t StringLen = Leaf->ConcatLen - Leaf->size();
+
+    // Too short to be beneficial; skip it.
+    // FIXME: This isn't necessarily true for, say, X86. If we factor in
+    // instruction lengths we need more information than this.
+    if (StringLen < 2)
+      continue;
+
     size_t CallOverhead = 0;
     size_t SequenceOverhead = StringLen;