Add TargetInstrInfo::isSafeToMoveRegisterClassDefs. It returns true if it's safe to move an instruction which defines a value in the register class. Replace pre-splitting specific IgnoreRegisterClassBarriers with this new hook.

llvm-svn: 63936

2 files changed, 7 insertions, 8 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 8e3985f0998..577884969b3 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -2483,11 +2483,11 @@ ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
 }
 
 bool X86InstrInfo::
-IgnoreRegisterClassBarriers(const TargetRegisterClass *RC) const {
-  // FIXME: Ignore bariers of x87 stack registers for now. We can't
+isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
+  // FIXME: Return false for x87 stack register classes for now. We can't
   // allow any loads of these registers before FpGet_ST0_80.
-  return RC == &X86::CCRRegClass || RC == &X86::RFP32RegClass ||
-    RC == &X86::RFP64RegClass || RC == &X86::RFP80RegClass;
+  return !(RC == &X86::CCRRegClass || RC == &X86::RFP32RegClass ||
+           RC == &X86::RFP64RegClass || RC == &X86::RFP80RegClass);
 }
 
 const TargetRegisterClass *X86InstrInfo::getPointerRegClass() const {
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index 077de56a5d5..eba0baf3cae 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -406,10 +406,9 @@ public:
   virtual
   bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const;
 
-  /// IgnoreRegisterClassBarriers - Returns true if pre-register allocation
-  /// live interval splitting pass should ignore barriers of the specified
-  /// register class.
-  bool IgnoreRegisterClassBarriers(const TargetRegisterClass *RC) const;
+  /// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
+  /// instruction that defines the specified register class.
+  bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const;
 
   const TargetRegisterClass *getPointerRegClass() const;