Factor out LiveIntervalAnalysis' code to determine whether an instruction

is trivially rematerializable and integrate it into
TargetInstrInfo::isTriviallyReMaterializable. This way, all places that
need to know whether an instruction is rematerializable will get the
same answer.

This enables the useful parts of the aggressive-remat option by
default -- using AliasAnalysis to determine whether a memory location
is invariant, and removes the questionable parts -- rematting operations
with virtual register inputs that may not be live everywhere.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83687 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 3 deletions

diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index 27265da772..de22710fe6 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -275,11 +275,13 @@ public:
   /// isSafeToMove - Return true if it is safe to move this instruction. If
   /// SawStore is set to true, it means that there is a store (or call) between
   /// the instruction's location and its intended destination.
-  bool isSafeToMove(const TargetInstrInfo *TII, bool &SawStore) const;
+  bool isSafeToMove(const TargetInstrInfo *TII, bool &SawStore,
+                    AliasAnalysis *AA) const;
 
   /// isSafeToReMat - Return true if it's safe to rematerialize the specified
   /// instruction which defined the specified register instead of copying it.
-  bool isSafeToReMat(const TargetInstrInfo *TII, unsigned DstReg) const;
+  bool isSafeToReMat(const TargetInstrInfo *TII, unsigned DstReg,
+                     AliasAnalysis *AA) const;
 
   /// hasVolatileMemoryRef - Return true if this instruction may have a
   /// volatile memory reference, or if the information describing the
@@ -292,7 +294,7 @@ public:
   /// loading a value from the constant pool or from from the argument area of
   /// a function if it does not change.  This should only return true of *all*
   /// loads the instruction does are invariant (if it does multiple loads).
-  bool isInvariantLoad(AliasAnalysis *AA = 0) const;
+  bool isInvariantLoad(AliasAnalysis *AA) const;
 
   //
   // Debugging support