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misched: Allow disabling scoreboard hazard checking for subtargets with a

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valid itinerary but no pipeline stages.

An itinerary can contain useful scheduling information without specifying pipeline stages for each instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157977 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-06-05 03:44:32 +00:00
parent d05b46115f
commit d327d3dddd
2 changed files with 14 additions and 6 deletions
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2
include/llvm/CodeGen/ScheduleHazardRecognizer.h
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@ -46,6 +46,8 @@ public:
/// atIssueLimit - Return true if no more instructions may be issued in this /// atIssueLimit - Return true if no more instructions may be issued in this
/// cycle. /// cycle.
///
/// FIXME: remove this once MachineScheduler is the only client.
virtual bool atIssueLimit() const { return false; } virtual bool atIssueLimit() const { return false; }
/// getHazardType - Return the hazard type of emitting this node. There are /// getHazardType - Return the hazard type of emitting this node. There are

18
lib/CodeGen/ScoreboardHazardRecognizer.cpp
View File

@ -39,9 +39,9 @@ ScoreboardHazardRecognizer(const InstrItineraryData *II,
DebugType = ParentDebugType; DebugType = ParentDebugType;
#endif #endif
// Determine the maximum depth of any itinerary. This determines the // Determine the maximum depth of any itinerary. This determines the depth of
// depth of the scoreboard. We always make the scoreboard at least 1 // the scoreboard. We always make the scoreboard at least 1 cycle deep to
// cycle deep to avoid dealing with the boundary condition. // avoid dealing with the boundary condition.
unsigned ScoreboardDepth = 1; unsigned ScoreboardDepth = 1;
if (ItinData && !ItinData->isEmpty()) { if (ItinData && !ItinData->isEmpty()) {
IssueWidth = ItinData->IssueWidth; IssueWidth = ItinData->IssueWidth;
@ -63,16 +63,22 @@ ScoreboardHazardRecognizer(const InstrItineraryData *II,
// Find the next power-of-2 >= ItinDepth // Find the next power-of-2 >= ItinDepth
while (ItinDepth > ScoreboardDepth) { while (ItinDepth > ScoreboardDepth) {
ScoreboardDepth *= 2; 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); ReservedScoreboard.reset(ScoreboardDepth);
RequiredScoreboard.reset(ScoreboardDepth); RequiredScoreboard.reset(ScoreboardDepth);
DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = " if (!MaxLookAhead)
<< ScoreboardDepth << '\n'); DEBUG(dbgs() << "Disabled scoreboard hazard recognizer\n");
else
DEBUG(dbgs() << "Using scoreboard hazard recognizer: Depth = "
<< ScoreboardDepth << '\n');
} }
void ScoreboardHazardRecognizer::Reset() { void ScoreboardHazardRecognizer::Reset() {