[MachineScheduler] Fix for PR21807: minor code difference building with/without -g.

This patch fixes the issue reported as PR21807. There was a minor difference
in the generated code depending on the -g flag.

The cause was that with -g the machine scheduler used a different
scheduling strategy. This decision was based on the number of instructions
in a schedule region and included debug instructions in that count.

This patch fixes the issue in MISched and provides a test.

Patch by Russell Gallop!

llvm-svn: 224118

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 261942f534b..cc8f3a075e9 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -430,9 +430,11 @@ void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler) {
       // instruction stream until we find the nearest boundary.
       unsigned NumRegionInstrs = 0;
       MachineBasicBlock::iterator I = RegionEnd;
-      for(;I != MBB->begin(); --I, --RemainingInstrs, ++NumRegionInstrs) {
+      for(;I != MBB->begin(); --I, --RemainingInstrs) {
         if (isSchedBoundary(std::prev(I), MBB, MF, TII, IsPostRA))
           break;
+        if (!I->isDebugValue())
+          ++NumRegionInstrs;
       }
       // Notify the scheduler of the region, even if we may skip scheduling
       // it. Perhaps it still needs to be bundled.