[PATCH] D60839: [ScheduleDAGInstrs] Compute topological ordering on demand.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: MatzeB, atrick, efriedma, niravd.
Herald added subscribers: dexonsmith, hiraditya, mehdi_amini.
Herald added a project: LLVM.

In most cases, the topological ordering does not get changed in
ScheduleDAGInstrs. We can compute the ordering on demand, similar to
D60125 <https://reviews.llvm.org/D60125>.

This drastically cuts down the number of times we need to compute the
topological ordering, e.g. for SPEC2006, SPEC2k and MultiSource, we get
the following stats for -O3 -flto on X86 (showing the top reductions,
with small absolute values filtered). The smallest reduction is -50%.

I'll provide compile-time numbers after the weekend.

Tests: 243
Metric: pre-RA-sched.NumTopoInits

Program                                        rr-lazy   mi-lazy  diff
 test-suite...ngs-C/fixoutput/fixoutput.test   115.00      3.00   -97.4%
 test-suite...ks/Prolangs-C/cdecl/cdecl.test   957.00     26.00   -97.3%
 test-suite...math/automotive-basicmath.test   107.00      3.00   -97.2%
 test-suite...rolangs-C++/deriv2/deriv2.test   144.00      6.00   -95.8%
 test-suite...lowfish/security-blowfish.test   410.00     18.00   -95.6%
 test-suite...frame_layout/frame_layout.test   441.00     23.00   -94.8%
 test-suite...rolangs-C++/employ/employ.test   159.00     11.00   -93.1%
 test-suite...s/Ptrdist/anagram/anagram.test   157.00     11.00   -93.0%
 test-suite...s-C/unix-smail/unix-smail.test   829.00     59.00   -92.9%
 test-suite...chmarks/Olden/power/power.test   154.00     11.00   -92.9%
 test-suite...T95/147.vortex/147.vortex.test   19876.00  1434.00  -92.8%
 test-suite...000/255.vortex/255.vortex.test   19881.00  1435.00  -92.8%
 test-suite...ce/Applications/Burg/burg.test   2203.00   168.00   -92.4%
 test-suite...urce/Applications/hbd/hbd.test   1067.00    85.00   -92.0%
 test-suite...ternal/HMMER/hmmcalibrate.test   3145.00   251.00   -92.0%
 test-suite.../Applications/spiff/spiff.test   1037.00    84.00   -91.9%
 test-suite...SPEC/CINT95/130.li/130.li.test   5913.00   487.00   -91.8%
 test-suite.../CINT95/134.perl/134.perl.test   12532.00  1041.00  -91.7%
 test-suite...ce/Benchmarks/Olden/bh/bh.test   220.00     19.00   -91.4%
 test-suite :: External/Nurbs/nurbs.test       2304.00   206.00   -91.1%
 test-suite...arks/VersaBench/dbms/dbms.test   773.00     75.00   -90.3%
 test-suite...ce/Applications/siod/siod.test   9043.00   878.00   -90.3%
 test-suite...pplications/treecc/treecc.test   4510.00   438.00   -90.3%
 test-suite...T2006/456.hmmer/456.hmmer.test   7093.00   697.00   -90.2%
 test-suite...s-C/Pathfinder/PathFinder.test   882.00     87.00   -90.1%
 test-suite.../CINT2000/176.gcc/176.gcc.test   64978.00  6721.00  -89.7%
 test-suite...cations/hexxagon/hexxagon.test   657.00     69.00   -89.5%
 test-suite...fice-ispell/office-ispell.test   2712.00   285.00   -89.5%
 test-suite.../CINT2006/403.gcc/403.gcc.test   139613.00 14992.00 -89.3%
 test-suite...lications/ClamAV/clamscan.test   25880.00  2785.00  -89.2%


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D60839

Files:
  llvm/include/llvm/CodeGen/ScheduleDAGInstrs.h
  llvm/lib/CodeGen/ScheduleDAGInstrs.cpp


Index: llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
===================================================================
--- llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -969,7 +969,7 @@
   CurrentVRegDefs.clear();
   CurrentVRegUses.clear();
 
-  Topo.InitDAGTopologicalSorting();
+  Topo.MarkDirty();
 }
 
 raw_ostream &llvm::operator<<(raw_ostream &OS, const PseudoSourceValue* PSV) {
@@ -1158,7 +1158,7 @@
     // If Pred is reachable from Succ, then the edge creates a cycle.
     if (Topo.IsReachable(PredDep.getSUnit(), SuccSU))
       return false;
-    Topo.AddPred(SuccSU, PredDep.getSUnit());
+    Topo.AddPredQueued(SuccSU, PredDep.getSUnit());
   }
   SuccSU->addPred(PredDep, /*Required=*/!PredDep.isArtificial());
   // Return true regardless of whether a new edge needed to be inserted.
Index: llvm/include/llvm/CodeGen/ScheduleDAGInstrs.h
===================================================================
--- llvm/include/llvm/CodeGen/ScheduleDAGInstrs.h
+++ llvm/include/llvm/CodeGen/ScheduleDAGInstrs.h
@@ -346,6 +346,7 @@
     /// True if an edge can be added from PredSU to SuccSU without creating
     /// a cycle.
     bool canAddEdge(SUnit *SuccSU, SUnit *PredSU);
+    void MarkDirty() { Topo.MarkDirty(); }
 
     /// Add a DAG edge to the given SU with the given predecessor
     /// dependence data.


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