From: Bob Wilson <bob.wilson@apple.com>
Date: Tue, 26 Oct 2010 00:02:21 +0000 (+0000)
Subject: Change if-conversion to keep track of the extra cost due to microcoded
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2ad40d34947ced36d96f351f6c2a4d57a044e2a4;p=oota-llvm.git

Change if-conversion to keep track of the extra cost due to microcoded
instructions separately from the count of non-predicated instructions.  The
instruction count is used in places to determine how many instructions to
copy, predicate, etc. and things get confused if that count includes the
extra cost for microcoded ops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117332 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index 1ee27f0e38d..ce3eda78913 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -93,6 +93,7 @@ namespace {
     /// ClobbersPred    - True if BB could modify predicates (e.g. has
     ///                   cmp, call, etc.)
     /// NonPredSize     - Number of non-predicated instructions.
+    /// ExtraCost       - Extra cost for microcoded instructions.
     /// BB              - Corresponding MachineBasicBlock.
     /// TrueBB / FalseBB- See AnalyzeBranch().
     /// BrCond          - Conditions for end of block conditional branches.
@@ -108,6 +109,7 @@ namespace {
       bool CannotBeCopied  : 1;
       bool ClobbersPred    : 1;
       unsigned NonPredSize;
+      unsigned ExtraCost;
       MachineBasicBlock *BB;
       MachineBasicBlock *TrueBB;
       MachineBasicBlock *FalseBB;
@@ -117,7 +119,7 @@ namespace {
                  IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
                  HasFallThrough(false), IsUnpredicable(false),
                  CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
-                 BB(0), TrueBB(0), FalseBB(0) {}
+                 ExtraCost(0), BB(0), TrueBB(0), FalseBB(0) {}
     };
 
     /// IfcvtToken - Record information about pending if-conversions to attempt:
@@ -652,6 +654,7 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
 
   // Then scan all the instructions.
   BBI.NonPredSize = 0;
+  BBI.ExtraCost = 0;
   BBI.ClobbersPred = false;
   for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
        I != E; ++I) {
@@ -667,8 +670,10 @@ void IfConverter::ScanInstructions(BBInfo &BBI) {
 
     if (!isCondBr) {
       if (!isPredicated) {
+        BBI.NonPredSize++;
         unsigned NumOps = TII->getNumMicroOps(&*I, InstrItins);
-        BBI.NonPredSize += NumOps;
+        if (NumOps > 1)
+          BBI.ExtraCost += NumOps-1;
       } else if (!AlreadyPredicated) {
         // FIXME: This instruction is already predicated before the
         // if-conversion pass. It's probably something like a conditional move.
@@ -815,8 +820,10 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
   }
   
   if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) &&
-      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize - (Dups + Dups2),
-                         *FalseBBI.BB, FalseBBI.NonPredSize - (Dups + Dups2),
+      MeetIfcvtSizeLimit(*TrueBBI.BB, (TrueBBI.NonPredSize - (Dups + Dups2) +
+                                       TrueBBI.ExtraCost),
+                         *FalseBBI.BB, (FalseBBI.NonPredSize - (Dups + Dups2) +
+                                        FalseBBI.ExtraCost),
                          Prediction, Confidence) &&
       FeasibilityAnalysis(TrueBBI, BBI.BrCond) &&
       FeasibilityAnalysis(FalseBBI, RevCond)) {
@@ -834,7 +841,7 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
   }
 
   if (ValidTriangle(TrueBBI, FalseBBI, false, Dups, Prediction, Confidence) &&
-      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize,
+      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost,
                          Prediction, Confidence) &&
       FeasibilityAnalysis(TrueBBI, BBI.BrCond, true)) {
     // Triangle:
@@ -849,7 +856,7 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
   }
 
   if (ValidTriangle(TrueBBI, FalseBBI, true, Dups, Prediction, Confidence) &&
-      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize,
+      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost,
                          Prediction, Confidence) &&
       FeasibilityAnalysis(TrueBBI, BBI.BrCond, true, true)) {
     Tokens.push_back(new IfcvtToken(BBI, ICTriangleRev, TNeedSub, Dups));
@@ -857,7 +864,7 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
   }
 
   if (ValidSimple(TrueBBI, Dups, Prediction, Confidence) &&
-      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize,
+      MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost,
                          Prediction, Confidence) &&
       FeasibilityAnalysis(TrueBBI, BBI.BrCond)) {
     // Simple (split, no rejoin):
@@ -875,7 +882,8 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
     // Try the other path...
     if (ValidTriangle(FalseBBI, TrueBBI, false, Dups,
                       1.0-Prediction, Confidence) &&
-        MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize,
+        MeetIfcvtSizeLimit(*FalseBBI.BB,
+                           FalseBBI.NonPredSize + FalseBBI.ExtraCost,
                            1.0-Prediction, Confidence) &&
         FeasibilityAnalysis(FalseBBI, RevCond, true)) {
       Tokens.push_back(new IfcvtToken(BBI, ICTriangleFalse, FNeedSub, Dups));
@@ -884,7 +892,8 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
 
     if (ValidTriangle(FalseBBI, TrueBBI, true, Dups,
                       1.0-Prediction, Confidence) &&
-        MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize,
+        MeetIfcvtSizeLimit(*FalseBBI.BB,
+                           FalseBBI.NonPredSize + FalseBBI.ExtraCost,
                            1.0-Prediction, Confidence) &&
         FeasibilityAnalysis(FalseBBI, RevCond, true, true)) {
       Tokens.push_back(new IfcvtToken(BBI, ICTriangleFRev, FNeedSub, Dups));
@@ -892,7 +901,8 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
     }
 
     if (ValidSimple(FalseBBI, Dups, 1.0-Prediction, Confidence) &&
-        MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize,
+        MeetIfcvtSizeLimit(*FalseBBI.BB,
+                           FalseBBI.NonPredSize + FalseBBI.ExtraCost,
                            1.0-Prediction, Confidence) &&
         FeasibilityAnalysis(FalseBBI, RevCond)) {
       Tokens.push_back(new IfcvtToken(BBI, ICSimpleFalse, FNeedSub, Dups));
@@ -1422,8 +1432,10 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
 
     MachineInstr *MI = MF.CloneMachineInstr(I);
     ToBBI.BB->insert(ToBBI.BB->end(), MI);
+    ToBBI.NonPredSize++;
     unsigned NumOps = TII->getNumMicroOps(MI, InstrItins);
-    ToBBI.NonPredSize += NumOps;
+    if (NumOps > 1)
+      ToBBI.ExtraCost += NumOps-1;
 
     if (!TII->isPredicated(I) && !MI->isDebugValue()) {
       if (!TII->PredicateInstruction(MI, Cond)) {
@@ -1497,7 +1509,9 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) {
   FromBBI.Predicate.clear();
 
   ToBBI.NonPredSize += FromBBI.NonPredSize;
+  ToBBI.ExtraCost += FromBBI.ExtraCost;
   FromBBI.NonPredSize = 0;
+  FromBBI.ExtraCost = 0;
 
   ToBBI.ClobbersPred |= FromBBI.ClobbersPred;
   ToBBI.HasFallThrough = FromBBI.HasFallThrough;