Add initial support for back-scheduling address computations,
especially in the case of addresses computed from loop induction
variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61075 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LatencyPriorityQueue.cpp b/lib/CodeGen/LatencyPriorityQueue.cpp
index 7ad9ac9..2e7b89c 100644
--- a/lib/CodeGen/LatencyPriorityQueue.cpp
+++ b/lib/CodeGen/LatencyPriorityQueue.cpp
@@ -19,6 +19,14 @@
using namespace llvm;
bool latency_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
+ // The isScheduleHigh flag allows nodes with wraparound dependencies that
+ // cannot easily be modeled as edges with latencies to be scheduled as
+ // soon as possible in a top-down schedule.
+ if (LHS->isScheduleHigh && !RHS->isScheduleHigh)
+ return false;
+ if (!LHS->isScheduleHigh && RHS->isScheduleHigh)
+ return true;
+
unsigned LHSNum = LHS->NodeNum;
unsigned RHSNum = RHS->NodeNum;