Add trace accessor methods, implement primitive if-conversion heuristic.
Compare the critical paths of the two traces through an if-conversion
candidate. If the difference is larger than the branch brediction
penalty, reject the if-conversion. If would never pay.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161433 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineTraceMetrics.cpp b/lib/CodeGen/MachineTraceMetrics.cpp
index 1c0894e..09b6e9c 100644
--- a/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/lib/CodeGen/MachineTraceMetrics.cpp
@@ -14,6 +14,7 @@
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/Debug.h"
@@ -1017,6 +1018,29 @@
return Trace(*this, BlockInfo[MBB->getNumber()]);
}
+unsigned
+MachineTraceMetrics::Trace::getInstrSlack(const MachineInstr *MI) const {
+ assert(MI && "Not an instruction.");
+ assert(getBlockNum() == unsigned(MI->getParent()->getNumber()) &&
+ "MI must be in the trace center block");
+ InstrCycles Cyc = getInstrCycles(MI);
+ return getCriticalPath() - (Cyc.Depth + Cyc.Height);
+}
+
+unsigned MachineTraceMetrics::Trace::getResourceDepth(bool Bottom) const {
+ // For now, we compute the resource depth from instruction count / issue
+ // width. Eventually, we should compute resource depth per functional unit
+ // and return the max.
+ unsigned Instrs = TBI.InstrDepth;
+ if (Bottom)
+ Instrs += TE.MTM.BlockInfo[getBlockNum()].InstrCount;
+ if (const MCSchedModel *Model = TE.MTM.ItinData->SchedModel)
+ if (Model->IssueWidth != 0)
+ return Instrs / Model->IssueWidth;
+ // Assume issue width 1 without a schedule model.
+ return Instrs;
+}
+
void MachineTraceMetrics::Ensemble::print(raw_ostream &OS) const {
OS << getName() << " ensemble:\n";
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
