diff options
| -rw-r--r-- | include/llvm/CodeGen/ScheduleHazardRecognizer.h | 2 | ||||
| -rw-r--r-- | lib/CodeGen/ScoreboardHazardRecognizer.cpp | 18 |
2 files changed, 14 insertions, 6 deletions
diff --git a/include/llvm/CodeGen/ScheduleHazardRecognizer.h b/include/llvm/CodeGen/ScheduleHazardRecognizer.h index fd62841918..9dfa3446ef 100644 --- a/include/llvm/CodeGen/ScheduleHazardRecognizer.h +++ b/include/llvm/CodeGen/ScheduleHazardRecognizer.h @@ -46,6 +46,8 @@ public: /// atIssueLimit - Return true if no more instructions may be issued in this /// cycle. + /// + /// FIXME: remove this once MachineScheduler is the only client. virtual bool atIssueLimit() const { return false; } /// getHazardType - Return the hazard type of emitting this node. There are diff --git a/lib/CodeGen/ScoreboardHazardRecognizer.cpp b/lib/CodeGen/ScoreboardHazardRecognizer.cpp index f3bad94319..ac62d7ef0d 100644 --- a/lib/CodeGen/ScoreboardHazardRecognizer.cpp +++ b/lib/CodeGen/ScoreboardHazardRecognizer.cpp @@ -39,9 +39,9 @@ ScoreboardHazardRecognizer(const InstrItineraryData *II, DebugType = ParentDebugType; #endif - // Determine the maximum depth of any itinerary. This determines the - // depth of the scoreboard. We always make the scoreboard at least 1 - // cycle deep to avoid dealing with the boundary condition. + // Determine the maximum depth of any itinerary. This determines the depth of + // the scoreboard. We always make the scoreboard at least 1 cycle deep to + // avoid dealing with the boundary condition. unsigned ScoreboardDepth = 1; if (ItinData && !ItinData->isEmpty()) { IssueWidth = ItinData->IssueWidth; @@ -63,16 +63,22 @@ ScoreboardHazardRecognizer(const InstrItineraryData *II, // Find the next power-of-2 >= ItinDepth while (ItinDepth > ScoreboardDepth) { ScoreboardDepth *= 2; + // Don't set MaxLookAhead until we find at least one nonzero stage. + // This way, an itinerary with no stages has MaxLookAhead==0, which + // completely bypasses the scoreboard hazard logic. + MaxLookAhead = ScoreboardDepth; } } - MaxLookAhead = ScoreboardDepth; } ReservedScoreboard.reset(ScoreboardDepth); RequiredScoreboard.reset(ScoreboardDepth); - DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = " - << ScoreboardDepth << '\n'); + if (!MaxLookAhead) + DEBUG(dbgs() << "Disabled scoreboard hazard recognizer\n"); + else + DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = " + << ScoreboardDepth << '\n'); } void ScoreboardHazardRecognizer::Reset() { |