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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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18
lib/CodeGen/ScoreboardHazardRecognizer.cpp
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@ -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() {