[Packetizer] Add a check whether an instruction should be packetized now
Add a function VLIWPacketizerList::shouldAddToPacket, which will allow
specific implementations to decide if it is profitable to add given
instruction to the current packet.
llvm-svn: 255780
diff --git a/llvm/include/llvm/CodeGen/DFAPacketizer.h b/llvm/include/llvm/CodeGen/DFAPacketizer.h
index 11d959b..40ec201 100644
--- a/llvm/include/llvm/CodeGen/DFAPacketizer.h
+++ b/llvm/include/llvm/CodeGen/DFAPacketizer.h
@@ -186,6 +186,16 @@
return true;
}
+ // Check if the packetizer should try to add the given instruction to
+ // the current packet. One reasons for which it may not be desirable
+ // to include an instruction in the current packet could be that it
+ // would cause a stall.
+ // If this function returns "false", the current packet will be ended,
+ // and the instruction will be added to the next packet.
+ virtual bool shouldAddToPacket(const MachineInstr *MI) {
+ return true;
+ }
+
// isLegalToPacketizeTogether - Is it legal to packetize SUI and SUJ
// together.
virtual bool isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) {
diff --git a/llvm/lib/CodeGen/DFAPacketizer.cpp b/llvm/lib/CodeGen/DFAPacketizer.cpp
index 80e03d9..af6b6a3 100644
--- a/llvm/lib/CodeGen/DFAPacketizer.cpp
+++ b/llvm/lib/CodeGen/DFAPacketizer.cpp
@@ -239,7 +239,7 @@
// Ask DFA if machine resource is available for MI.
bool ResourceAvail = ResourceTracker->canReserveResources(MI);
- if (ResourceAvail) {
+ if (ResourceAvail && shouldAddToPacket(MI)) {
// Dependency check for MI with instructions in CurrentPacketMIs.
for (std::vector<MachineInstr*>::iterator VI = CurrentPacketMIs.begin(),
VE = CurrentPacketMIs.end(); VI != VE; ++VI) {
@@ -258,7 +258,8 @@
} // !isLegalToPacketizeTogether.
} // For all instructions in CurrentPacketMIs.
} else {
- // End the packet if resource is not available.
+ // End the packet if resource is not available, or if the instruction
+ // shoud not be added to the current packet.
endPacket(MBB, MI);
}