From 12f0dc6bb556976f22d89ebcf42bce273c9e7d38 Mon Sep 17 00:00:00 2001 From: Andrew Trick Date: Thu, 14 Apr 2011 05:15:06 +0000 Subject: In the pre-RA scheduler, maintain cmp+br proximity. This is done by pushing physical register definitions close to their use, which happens to handle flag definitions if they're not glued to the branch. This seems to be generally a good thing though, so I didn't need to add a target hook yet. The primary motivation is to generate code closer to what people expect and rule out missed opportunity from enabling macro-op fusion. As a side benefit, we get several 2-5% gains on x86 benchmarks. There is one regression: SingleSource/Benchmarks/Shootout/lists slows down be -10%. But this is an independent scheduler bug that will be tracked separately. See rdar://problem/9283108. Incidentally, pre-RA scheduling is only half the solution. Fixing the later passes is tracked by: [pre-RA-sched] on x86, attempt to schedule CMP/TEST adjacent with condition jump Fixes: Scheduler unnecessary break of cmp/jump fusion git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129508 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp') diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp index 078533be84..b258e6eefe 100644 --- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp +++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp @@ -87,6 +87,8 @@ SUnit *ScheduleDAGSDNodes::Clone(SUnit *Old) { SU->isCommutable = Old->isCommutable; SU->hasPhysRegDefs = Old->hasPhysRegDefs; SU->hasPhysRegClobbers = Old->hasPhysRegClobbers; + SU->isScheduleHigh = Old->isScheduleHigh; + SU->isScheduleLow = Old->isScheduleLow; SU->SchedulingPref = Old->SchedulingPref; Old->isCloned = true; return SU; @@ -335,6 +337,12 @@ void ScheduleDAGSDNodes::BuildSchedUnits() { if (!HasGlueUse) break; } + // Schedule zero-latency TokenFactor below any nodes that may increase the + // schedule height. Otherwise, ancestors of the TokenFactor may appear to + // have false stalls. + if (NI->getOpcode() == ISD::TokenFactor) + NodeSUnit->isScheduleLow = true; + // If there are glue operands involved, N is now the bottom-most node // of the sequence of nodes that are glued together. // Update the SUnit. -- cgit v1.2.3-18-g5258