[MC][Tablegen] Allow models to describe the retire control unit for llvm-mca.
This patch adds the ability to describe properties of the hardware retire
control unit.
Tablegen class RetireControlUnit has been added for this purpose (see
TargetSchedule.td).
A RetireControlUnit specifies the size of the reorder buffer, as well as the
maximum number of opcodes that can be retired every cycle.
A zero (or negative) value for the reorder buffer size means: "the size is
unknown". If the size is unknown, then llvm-mca defaults it to the value of
field SchedMachineModel::MicroOpBufferSize. A zero or negative number of
opcodes retired per cycle means: "there is no restriction on the number of
instructions that can be retired every cycle".
Models can optionally specify an instance of RetireControlUnit. There can only
be up-to one RetireControlUnit definition per scheduling model.
Information related to the RCU (RetireControlUnit) is stored in (two new fields
of) MCExtraProcessorInfo. llvm-mca loads that information when it initializes
the DispatchUnit / RetireControlUnit (see Dispatch.h/Dispatch.cpp).
This patch fixes PR36661.
Differential Revision: https://reviews.llvm.org/D45259
llvm-svn: 329304
diff --git a/llvm/tools/llvm-mca/Dispatch.cpp b/llvm/tools/llvm-mca/Dispatch.cpp
index 383737a..ce329b4 100644
--- a/llvm/tools/llvm-mca/Dispatch.cpp
+++ b/llvm/tools/llvm-mca/Dispatch.cpp
@@ -251,6 +251,24 @@
}
#endif
+RetireControlUnit::RetireControlUnit(const llvm::MCSchedModel &SM,
+ DispatchUnit *DU)
+ : NextAvailableSlotIdx(0), CurrentInstructionSlotIdx(0),
+ AvailableSlots(SM.MicroOpBufferSize), MaxRetirePerCycle(0), Owner(DU) {
+ // Check if the scheduling model provides extra information about the machine
+ // processor. If so, then use that information to set the reorder buffer size
+ // and the maximum number of instructions retired per cycle.
+ if (SM.hasExtraProcessorInfo()) {
+ const MCExtraProcessorInfo &EPI = SM.getExtraProcessorInfo();
+ if (EPI.ReorderBufferSize)
+ AvailableSlots = EPI.ReorderBufferSize;
+ MaxRetirePerCycle = EPI.MaxRetirePerCycle;
+ }
+
+ assert(AvailableSlots && "Invalid reorder buffer size!");
+ Queue.resize(AvailableSlots);
+}
+
// Reserves a number of slots, and returns a new token.
unsigned RetireControlUnit::reserveSlot(unsigned Index, unsigned NumMicroOps) {
assert(isAvailable(NumMicroOps));