EXTRACT_SUBREG coalescing support. The coalescer now treats EXTRACT_SUBREG like
(almost) a register copy. However, it always coalesced to the register of the
RHS (the super-register). All uses of the result of a EXTRACT_SUBREG are sub-
register uses which adds subtle complications to load folding, spiller rewrite,
etc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42899 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 1634c78..1ac955a 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -220,6 +220,24 @@
return -1;
}
+/// isRegReDefinedByTwoAddr - Returns true if the Reg re-definition is due
+/// to two addr elimination.
+bool MachineInstr::isRegReDefinedByTwoAddr(unsigned Reg) const {
+ const TargetInstrDescriptor *TID = getInstrDescriptor();
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO1 = getOperand(i);
+ if (MO1.isRegister() && MO1.isDef() && MO1.getReg() == Reg) {
+ for (unsigned j = i+1; j < e; ++j) {
+ const MachineOperand &MO2 = getOperand(j);
+ if (MO2.isRegister() && MO2.isUse() && MO2.getReg() == Reg &&
+ TID->getOperandConstraint(j, TOI::TIED_TO) == (int)i)
+ return true;
+ }
+ }
+ }
+ return false;
+}
+
/// copyKillDeadInfo - Copies kill / dead operand properties from MI.
///
void MachineInstr::copyKillDeadInfo(const MachineInstr *MI) {