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author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2010-05-19 20:36:22 +0000 |
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committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2010-05-19 20:36:22 +0000 |
commit | 7ebc4d63db05ac214d36bc01b4d60adadaf923e5 (patch) | |
tree | 3f1df7259be24bb781440916e2a2ba4868216143 /lib/CodeGen/MachineInstr.cpp | |
parent | aa6c72ec9579cf7a9e65cbc7a56c6a40e9c5ad47 (diff) | |
download | llvm-7ebc4d63db05ac214d36bc01b4d60adadaf923e5.tar.gz llvm-7ebc4d63db05ac214d36bc01b4d60adadaf923e5.tar.bz2 llvm-7ebc4d63db05ac214d36bc01b4d60adadaf923e5.tar.xz |
Add MachineInstr::readsVirtualRegister() in preparation for proper handling of
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
Diffstat (limited to 'lib/CodeGen/MachineInstr.cpp')
-rw-r--r-- | lib/CodeGen/MachineInstr.cpp | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp index d909fb0ef3..553b13938c 100644 --- a/lib/CodeGen/MachineInstr.cpp +++ b/lib/CodeGen/MachineInstr.cpp @@ -781,7 +781,30 @@ int MachineInstr::findRegisterUseOperandIdx(unsigned Reg, bool isKill, } return -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 MachineInstr::readsVirtualRegister(unsigned Reg) const { + bool PartDef = false; // Partial redefine + bool FullDef = false; // Full define + + for (unsigned i = 0, e = getNumOperands(); i != e; ++i) { + const MachineOperand &MO = getOperand(i); + if (!MO.isReg() || MO.getReg() != Reg) + continue; + if (MO.isUse()) + return true; + if (MO.getSubReg()) + PartDef = true; + else + FullDef = true; + } + // A partial register definition causes a read unless the full register is + // also defined. + return PartDef && !FullDef; +} + /// findRegisterDefOperandIdx() - Returns the operand index that is a def of /// the specified register or -1 if it is not found. If isDead is true, defs /// that are not dead are skipped. If TargetRegisterInfo is non-null, then it |