From: Dan Gohman <gohman@apple.com>
Date: Tue, 16 Dec 2008 02:38:22 +0000 (+0000)
Subject: Add a simple target-independent heuristic to allow targets with no
X-Git-Tag: android-x86-6.0-r1~1047^2~16833
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=aa2a113b16a904b4ad4420c68da7eca513a9fa69;p=android-x86%2Fexternal-llvm.git

Add a simple target-independent heuristic to allow targets with no
instruction itinerary data to back-schedule loads.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61070 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 30e1846ef8b..fa42d393a3b 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -225,6 +225,12 @@ void ScheduleDAGInstrs::ComputeLatency(SUnit *SU) {
   // all nodes flagged together into this SUnit.
   SU->Latency =
     InstrItins.getLatency(SU->getInstr()->getDesc().getSchedClass());
+
+  // Simplistic target-independent heuristic: assume that loads take
+  // extra time.
+  if (InstrItins.isEmpty())
+    if (SU->getInstr()->getDesc().mayLoad())
+      SU->Latency += 2;
 }
 
 void ScheduleDAGInstrs::dumpNode(const SUnit *SU) const {