MIsched: add an ILP window property to machine model.

This was an experimental option, but needs to be defined
per-target. e.g. PPC A2 needs to aggressively hide latency.

I converted some in-order scheduling tests to A2. Hal is working on
more test cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171946 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 9 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMScheduleA9.td b/lib/Target/ARM/ARMScheduleA9.td
index 404634fee9..4191931a5a 100644
--- a/lib/Target/ARM/ARMScheduleA9.td
+++ b/lib/Target/ARM/ARMScheduleA9.td
@@ -1887,6 +1887,9 @@ def CortexA9Model : SchedMachineModel {
   let LoadLatency = 2; // Optimistic load latency assuming bypass.
                        // This is overriden by OperandCycles if the
                        // Itineraries are queried instead.
+  let ILPWindow = 10; // Don't reschedule small blocks to hide
+                      // latency. Minimum latency requirements are already
+                      // modeled strictly by reserving resources.
   let MispredictPenalty = 8; // Based on estimate of pipeline depth.
 
   let Itineraries = CortexA9Itineraries;
diff --git a/lib/Target/X86/X86Schedule.td b/lib/Target/X86/X86Schedule.td
index c14407f9ac..d99d085298 100644
--- a/lib/Target/X86/X86Schedule.td
+++ b/lib/Target/X86/X86Schedule.td
@@ -470,12 +470,17 @@ def IIC_NOP : InstrItinClass;
 // latencies. Since these latencies are not used for pipeline hazards,
 // they do not need to be exact.
 //
+// ILPWindow=10 is an arbitrary threshold that approximates cycles of
+// latency hidden by instruction buffers. The actual value is not very
+// important but should be zero for inorder and nonzero for OOO processors.
+//
 // The GenericModel contains no instruciton itineraries.
 def GenericModel : SchedMachineModel {
   let IssueWidth = 4;
   let MinLatency = 0;
   let LoadLatency = 4;
   let HighLatency = 10;
+  let ILPWindow = 10;
 }
 
 include "X86ScheduleAtom.td"
diff --git a/lib/Target/X86/X86ScheduleAtom.td b/lib/Target/X86/X86ScheduleAtom.td
index 87102614cc..1e5f2d6c9a 100644
--- a/lib/Target/X86/X86ScheduleAtom.td
+++ b/lib/Target/X86/X86ScheduleAtom.td
@@ -525,6 +525,7 @@ def AtomModel : SchedMachineModel {
                        // OperandCycles may be used for expected latency.
   let LoadLatency = 3; // Expected cycles, may be overriden by OperandCycles.
   let HighLatency = 30;// Expected, may be overriden by OperandCycles.
+  let ILPWindow = 0; // Always try to hide expected latency.
 
   let Itineraries = AtomItineraries;
 }