[SystemZ] Mark CC defs as dead whenever possible.
Marking implicit CC defs as dead everywhere except when CC is actually
defined and used explicitly, is important since the post-ra scheduler
will otherwise insert edges between instructions unnecessarily.
Also temporarily disable LA(Y)-> AGSI optimization in
foldMemoryOperandImpl(), since this inroduces a def of the CC reg,
which is illegal unless it is known to be dead.
Reviewed by Ulrich Weigand.
llvm-svn: 268215
diff --git a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
index 11b8878..3938db2 100644
--- a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -737,6 +737,14 @@
}
}
+static void transferDeadCC(MachineInstr *OldMI, MachineInstr *NewMI) {
+ if (OldMI->registerDefIsDead(SystemZ::CC)) {
+ MachineOperand *CCDef = NewMI->findRegisterDefOperand(SystemZ::CC);
+ if (CCDef != nullptr)
+ CCDef->setIsDead(true);
+ }
+}
+
// Used to return from convertToThreeAddress after replacing two-address
// instruction OldMI with three-address instruction NewMI.
static MachineInstr *finishConvertToThreeAddress(MachineInstr *OldMI,
@@ -750,6 +758,7 @@
LV->replaceKillInstruction(Op.getReg(), OldMI, NewMI);
}
}
+ transferDeadCC(OldMI, NewMI);
return NewMI;
}
@@ -842,19 +851,26 @@
unsigned Size = MFI->getObjectSize(FrameIndex);
unsigned Opcode = MI->getOpcode();
+// XXX This is an introduction of a CC def and is illegal! Reactivate
+// with a check of liveness of CC reg.
+#if 0
if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
if ((Opcode == SystemZ::LA || Opcode == SystemZ::LAY) &&
isInt<8>(MI->getOperand(2).getImm()) &&
!MI->getOperand(3).getReg()) {
// LA(Y) %reg, CONST(%reg) -> AGSI %mem, CONST
- return BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
+ MachineInstr *BuiltMI =
+ BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
get(SystemZ::AGSI))
.addFrameIndex(FrameIndex)
.addImm(0)
.addImm(MI->getOperand(2).getImm());
+ BuiltMI->findRegisterDefOperand(SystemZ::CC)->setIsDead(true);
+ return BuiltMI;
}
return nullptr;
}
+#endif
// All other cases require a single operand.
if (Ops.size() != 1)
@@ -870,11 +886,14 @@
isInt<8>(MI->getOperand(2).getImm())) {
// A(G)HI %reg, CONST -> A(G)SI %mem, CONST
Opcode = (Opcode == SystemZ::AHI ? SystemZ::ASI : SystemZ::AGSI);
- return BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
+ MachineInstr *BuiltMI =
+ BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
get(Opcode))
.addFrameIndex(FrameIndex)
.addImm(0)
.addImm(MI->getOperand(2).getImm());
+ transferDeadCC(MI, BuiltMI);
+ return BuiltMI;
}
if (Opcode == SystemZ::LGDR || Opcode == SystemZ::LDGR) {
@@ -963,6 +982,7 @@
MIB.addFrameIndex(FrameIndex).addImm(Offset);
if (MemDesc.TSFlags & SystemZII::HasIndex)
MIB.addReg(0);
+ transferDeadCC(MI, MIB);
return MIB;
}
}