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Add MachineInstr::readsVirtualRegister() in preparation for proper handling of

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partial redefines.

We are going to treat a partial redefine of a virtual register as a
read-modify-write:

  %reg1024:6 = OP

Unless the register is fully clobbered:

  %reg1024:6 = OP, %reg1024<imp-def>

MachineInstr::readsVirtualRegister() knows the difference. The first case is a
read, the second isn't.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104149 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2010-05-19 20:36:22 +00:00
parent aa6c72ec95
commit 7ebc4d63db
2 changed files with 31 additions and 1 deletions
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7
include/llvm/CodeGen/MachineInstr.h
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@@ -230,10 +230,17 @@ public:
/// readsRegister - Return true if the MachineInstr reads the specified
/// register. If TargetRegisterInfo is passed, then it also checks if there
/// is a read of a super-register.
/// This does not count partial redefines of virtual registers as reads:
/// %reg1024:6 = OP.
bool readsRegister(unsigned Reg, const TargetRegisterInfo *TRI = NULL) const {
return findRegisterUseOperandIdx(Reg, false, TRI) != -1;
}
/// readsVirtualRegister - Return true if the MachineInstr reads the specified
/// virtual register. Take into account that a partial define is a
/// read-modify-write operation.
bool readsVirtualRegister(unsigned Reg) const;
/// killsRegister - Return true if the MachineInstr kills the specified
/// register. If TargetRegisterInfo is passed, then it also checks if there is
/// a kill of a super-register.