From 8182347d70413174f2e80ea429801e887aee5cc3 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 12 Feb 2009 08:59:45 +0000
Subject: [PATCH] Replace one of burr scheduling heuristic with something more
 sensible. Now calcMaxScratches simply compute the number of true data
 dependencies. This actually improve a couple of tests in dejagnu suite as
 many tests in llvm nightly test suite.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64369 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../SelectionDAG/ScheduleDAGRRList.cpp        | 22 ++++---------------
 .../CodeGen/ARM/2008-11-19-ScavengerAssert.ll |  1 +
 test/CodeGen/X86/2008-08-05-SpillerBug.ll     |  2 +-
 3 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index a0652a72c94..912e8ed7f7c 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -916,7 +916,7 @@ CalcNodeSethiUllmanNumber(const SUnit *SU, std::vector<unsigned> &SUNumbers) {
     if (PredSethiUllman > SethiUllmanNumber) {
       SethiUllmanNumber = PredSethiUllman;
       Extra = 0;
-    } else if (PredSethiUllman == SethiUllmanNumber && !I->isCtrl())
+    } else if (PredSethiUllman == SethiUllmanNumber)
       ++Extra;
   }
 
@@ -1070,24 +1070,13 @@ static unsigned closestSucc(const SUnit *SU) {
 }
 
 /// calcMaxScratches - Returns an cost estimate of the worse case requirement
-/// for scratch registers. Live-in operands and live-out results don't count
-/// since they are "fixed".
+/// for scratch registers, i.e. number of data dependencies.
 static unsigned calcMaxScratches(const SUnit *SU) {
   unsigned Scratches = 0;
   for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
-       I != E; ++I) {
+       I != E; ++I)
     if (I->isCtrl()) continue;  // ignore chain preds
-    if (!I->getSUnit()->getNode() ||
-        I->getSUnit()->getNode()->getOpcode() != ISD::CopyFromReg)
       Scratches++;
-  }
-  for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
-       I != E; ++I) {
-    if (I->isCtrl()) continue;  // ignore chain succs
-    if (!I->getSUnit()->getNode() ||
-        I->getSUnit()->getNode()->getOpcode() != ISD::CopyToReg)
-      Scratches += 10;
-  }
   return Scratches;
 }
 
@@ -1120,10 +1109,7 @@ bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
   if (LDist != RDist)
     return LDist < RDist;
 
-  // Intuitively, it's good to push down instructions whose results are
-  // liveout so their long live ranges won't conflict with other values
-  // which are needed inside the BB. Further prioritize liveout instructions
-  // by the number of operands which are calculated within the BB.
+  // How many registers becomes live when the node is scheduled.
   unsigned LScratch = calcMaxScratches(left);
   unsigned RScratch = calcMaxScratches(right);
   if (LScratch != RScratch)
diff --git a/test/CodeGen/ARM/2008-11-19-ScavengerAssert.ll b/test/CodeGen/ARM/2008-11-19-ScavengerAssert.ll
index 3f0b94bf5b8..0a73b3fc257 100644
--- a/test/CodeGen/ARM/2008-11-19-ScavengerAssert.ll
+++ b/test/CodeGen/ARM/2008-11-19-ScavengerAssert.ll
@@ -1,4 +1,5 @@
 ; RUN: llvm-as < %s | llc -mtriple=arm-apple-darwin9
+; RUN: llvm-as < %s | llc -mtriple=arm-apple-darwin9 -stats |& grep asm-printer | grep 186
 
 	%"struct.Adv5::Ekin<3>" = type <{ i8 }>
 	%"struct.Adv5::X::Energyflux<3>" = type { double }
diff --git a/test/CodeGen/X86/2008-08-05-SpillerBug.ll b/test/CodeGen/X86/2008-08-05-SpillerBug.ll
index 868c4958623..5ae802d61e2 100644
--- a/test/CodeGen/X86/2008-08-05-SpillerBug.ll
+++ b/test/CodeGen/X86/2008-08-05-SpillerBug.ll
@@ -1,4 +1,4 @@
-; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin -disable-fp-elim -stats -info-output-file - | grep {Number of dead stores elided} | count 1
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin -disable-fp-elim -stats |& grep asm-printer | grep 57
 ; PR2568
 
 @g_3 = external global i16		; <i16*> [#uses=1]