[PATCH] D118773: [MachineLICM] Add shouldHoist method to TargetInstrInfo

[Carl Ritson via Phabricator via llvm-commits]

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Add a shouldHoist method to TargetInstrInfo which is queried by
MachineLICM to override hoisting decisions for a given target.
This mirrors functionality provided by shouldSink.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118773

Files:
  llvm/include/llvm/CodeGen/TargetInstrInfo.h
  llvm/lib/CodeGen/MachineLICM.cpp


Index: llvm/lib/CodeGen/MachineLICM.cpp
===================================================================
--- llvm/lib/CodeGen/MachineLICM.cpp
+++ llvm/lib/CodeGen/MachineLICM.cpp
@@ -999,6 +999,9 @@
   if (I.isConvergent())
     return false;
 
+  if (!TII->shouldHoist(I, CurLoop))
+    return false;
+
   return true;
 }
 
Index: llvm/include/llvm/CodeGen/TargetInstrInfo.h
===================================================================
--- llvm/include/llvm/CodeGen/TargetInstrInfo.h
+++ llvm/include/llvm/CodeGen/TargetInstrInfo.h
@@ -382,6 +382,16 @@
   /// to which instructions should be sunk.
   virtual bool shouldSink(const MachineInstr &MI) const { return true; }
 
+  /// Return true if the instruction should be hoisted by MachineLICM.
+  ///
+  /// MachineLICM determines on its own whether the instruction is safe to
+  /// hoist; this gives the target a hook to override the default behavior with
+  /// regards to which instructions should be hoisted from a given loop.
+  virtual bool shouldHoist(const MachineInstr &MI,
+                           const MachineLoop *FromLoop) const {
+    return true;
+  }
+
   /// Re-issue the specified 'original' instruction at the
   /// specific location targeting a new destination register.
   /// The register in Orig->getOperand(0).getReg() will be substituted by


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