[MISched] Use SchedRegion in overrideSchedPolicy and overridePostRASchedPolicy (#149297)

This patch updates `overrideSchedPolicy` and `overridePostRASchedPolicy`
to take a
`SchedRegion` parameter instead of just `NumRegionInstrs`. This provides
access to both the
instruction range and the parent `MachineBasicBlock`, which enables
looking up function-level
attributes.

With this change, targets can select post-RA scheduling direction per
function using a function
attribute. For example:

```cpp
void overridePostRASchedPolicy(MachineSchedPolicy &Policy,
                               const SchedRegion &Region) const {
  const Function &F = Region.RegionBegin->getMF()->getFunction();
  Attribute Attr = F.getFnAttribute("amdgpu-post-ra-direction");
  ...
}

1 files changed, 4 insertions, 20 deletions

diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 76cba29..9d5c39c 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -771,24 +771,6 @@ static bool isSchedBoundary(MachineBasicBlock::iterator MI,
          MI->isFakeUse();
 }
 
-/// A region of an MBB for scheduling.
-namespace {
-struct SchedRegion {
-  /// RegionBegin is the first instruction in the scheduling region, and
-  /// RegionEnd is either MBB->end() or the scheduling boundary after the
-  /// last instruction in the scheduling region. These iterators cannot refer
-  /// to instructions outside of the identified scheduling region because
-  /// those may be reordered before scheduling this region.
-  MachineBasicBlock::iterator RegionBegin;
-  MachineBasicBlock::iterator RegionEnd;
-  unsigned NumRegionInstrs;
-
-  SchedRegion(MachineBasicBlock::iterator B, MachineBasicBlock::iterator E,
-              unsigned N) :
-    RegionBegin(B), RegionEnd(E), NumRegionInstrs(N) {}
-};
-} // end anonymous namespace
-
 using MBBRegionsVector = SmallVector<SchedRegion, 16>;
 
 static void
@@ -3725,7 +3707,8 @@ void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin,
   RegionPolicy.OnlyBottomUp = true;
 
   // Allow the subtarget to override default policy.
-  MF.getSubtarget().overrideSchedPolicy(RegionPolicy, NumRegionInstrs);
+  SchedRegion Region(Begin, End, NumRegionInstrs);
+  MF.getSubtarget().overrideSchedPolicy(RegionPolicy, Region);
 
   // After subtarget overrides, apply command line options.
   if (!EnableRegPressure) {
@@ -4338,7 +4321,8 @@ void PostGenericScheduler::initPolicy(MachineBasicBlock::iterator Begin,
   RegionPolicy.OnlyBottomUp = false;
 
   // Allow the subtarget to override default policy.
-  MF.getSubtarget().overridePostRASchedPolicy(RegionPolicy, NumRegionInstrs);
+  SchedRegion Region(Begin, End, NumRegionInstrs);
+  MF.getSubtarget().overridePostRASchedPolicy(RegionPolicy, Region);
 
   // After subtarget overrides, apply command line options.
   if (PostRADirection == MISched::TopDown) {