Handle early-clobber registers in the aggressive anti-dep breaker
The aggressive anti-dep breaker, used by the PowerPC backend during post-RA
scheduling (but is available to all targets), did not handle early-clobber MI
operands (at all). When constructing the list of available registers for the
replacement of some def operand, check the using instructions, and remove
registers assigned to early-clobbered defs from the set.
Fixes PR21452.
llvm-svn: 223727
diff --git a/llvm/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/llvm/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index 91c1314..69c3685 100644
--- a/llvm/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/llvm/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -673,6 +673,21 @@
goto next_super_reg;
}
+ // We cannot rename 'Reg' to 'NewReg' if one of the uses of 'Reg' also
+ // defines 'NewReg' via an early-clobber operand.
+ auto Range = RegRefs.equal_range(Reg);
+ for (auto Q = Range.first, QE = Range.second; Q != QE; ++Q) {
+ auto UseMI = Q->second.Operand->getParent();
+ int Idx = UseMI->findRegisterDefOperandIdx(NewReg, false, true, TRI);
+ if (Idx == -1)
+ continue;
+
+ if (UseMI->getOperand(Idx).isEarlyClobber()) {
+ DEBUG(dbgs() << "(ec)");
+ goto next_super_reg;
+ }
+ }
+
// Record that 'Reg' can be renamed to 'NewReg'.
RenameMap.insert(std::pair<unsigned, unsigned>(Reg, NewReg));
}