Use MachineBranchProbabilityInfo in If-Conversion instead of its own heuristics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136826 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index 6cb22778caf9978e305b93683fc98770c50c24b3..c4e274db45e7ca9d29f8005462d4d917d0cfaa7c 100644 (file)
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -16,14 +16,13 @@
 #include "llvm/Function.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/Codegen/MachineBranchProbabilityInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Support/BranchProbability.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -154,7 +153,8 @@ namespace {
     const TargetInstrInfo *TII;
     const TargetRegisterInfo *TRI;
     const InstrItineraryData *InstrItins;
-    const MachineLoopInfo *MLI;
+    const MachineBranchProbabilityInfo *MBPI;
+
     bool MadeChange;
     int FnNum;
   public:
@@ -162,9 +162,9 @@ namespace {
     IfConverter() : MachineFunctionPass(ID), FnNum(-1) {
       initializeIfConverterPass(*PassRegistry::getPassRegistry());
     }
-    
+
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.addRequired<MachineLoopInfo>();
+      AU.addRequired<MachineBranchProbabilityInfo>();
       MachineFunctionPass::getAnalysisUsage(AU);
     }
 
@@ -252,7 +252,7 @@ namespace {
 }
 
 INITIALIZE_PASS_BEGIN(IfConverter, "if-converter", "If Converter", false, false)
-INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
+INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
 INITIALIZE_PASS_END(IfConverter, "if-converter", "If Converter", false, false)
 
 FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
@@ -261,7 +261,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
   TLI = MF.getTarget().getTargetLowering();
   TII = MF.getTarget().getInstrInfo();
   TRI = MF.getTarget().getRegisterInfo();
-  MLI = &getAnalysis<MachineLoopInfo>();
+  MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
   InstrItins = MF.getTarget().getInstrItineraryData();
   if (!TII) return false;
 
@@ -790,28 +790,9 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
   bool TNeedSub = TrueBBI.Predicate.size() > 0;
   bool FNeedSub = FalseBBI.Predicate.size() > 0;
   bool Enqueued = false;
-  
-  // Try to predict the branch, using loop info to guide us.
-  // General heuristics are:
-  //   - backedge -> 90% taken
-  //   - early exit -> 20% taken
-  //   - branch predictor confidence -> 90%
-  BranchProbability Prediction(5, 10);
-  MachineLoop *Loop = MLI->getLoopFor(BB);
-  if (Loop) {
-    if (TrueBBI.BB == Loop->getHeader())
-      Prediction = BranchProbability(9, 10);
-    else if (FalseBBI.BB == Loop->getHeader())
-      Prediction = BranchProbability(1, 10);
-
-    MachineLoop *TrueLoop = MLI->getLoopFor(TrueBBI.BB);
-    MachineLoop *FalseLoop = MLI->getLoopFor(FalseBBI.BB);
-    if (!TrueLoop || TrueLoop->getParentLoop() == Loop)
-      Prediction = BranchProbability(2, 10);
-    else if (!FalseLoop || FalseLoop->getParentLoop() == Loop)
-      Prediction = BranchProbability(8, 10);
-  }
-  
+
+  BranchProbability Prediction = MBPI->getEdgeProbability(BB, TrueBBI.BB);
+
   if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) &&
       MeetIfcvtSizeLimit(*TrueBBI.BB, (TrueBBI.NonPredSize - (Dups + Dups2) +
                                        TrueBBI.ExtraCost), TrueBBI.ExtraCost2,

diff --git a/test/CodeGen/ARM/ifcvt4.ll b/test/CodeGen/ARM/ifcvt4.ll
index f28c61b9787ffae3e948d13d201ff3c1d024ca07..d099f516814ce3352b92d409309239db8db2dbad 100644 (file)
--- a/test/CodeGen/ARM/ifcvt4.ll
+++ b/test/CodeGen/ARM/ifcvt4.ll
@@ -1,8 +1,10 @@
-; RUN: llc < %s -march=arm
-; RUN: llc < %s -march=arm | grep subgt | count 1
-; RUN: llc < %s -march=arm | grep suble | count 1
-; FIXME: Check for # of unconditional branch after adding branch folding post ifcvt.
+; RUN: llc < %s -march=arm | FileCheck %s
 
+; Do not if-convert when branches go to the different loops.
+; CHECK: _t:
+; CHECK-NOT: subgt
+; CHECK-NOT: suble
+; Don't use
 define i32 @t(i32 %a, i32 %b) {
 entry:
        %tmp1434 = icmp eq i32 %a, %b           ; <i1> [#uses=1]

diff --git a/test/CodeGen/ARM/indirectbr.ll b/test/CodeGen/ARM/indirectbr.ll
index 25a0f936544e1508a7440973d4187d939f703c5a..341c33f84ff3ee877fdda9cc0c71c94bbaf6e370 100644 (file)
--- a/test/CodeGen/ARM/indirectbr.ll
+++ b/test/CodeGen/ARM/indirectbr.ll
@@ -22,7 +22,6 @@ bb2:                                              ; preds = %entry, %bb3
   %gotovar.4.0 = phi i8* [ %gotovar.4.0.pre, %bb3 ], [ %0, %entry ] ; <i8*> [#uses=1]
 ; ARM: bx
 ; THUMB: mov pc,
-; THUMB2: mov pc,
   indirectbr i8* %gotovar.4.0, [label %L5, label %L4, label %L3, label %L2, label %L1]
 
 bb3:                                              ; preds = %entry

diff --git a/test/CodeGen/Thumb2/2010-06-21-TailMergeBug.ll b/test/CodeGen/Thumb2/2010-06-21-TailMergeBug.ll
index f91e1c9febe2f4697b65f803af2ece747fa4b538..244d0bb8f720ec779ea219878b8f60831d28b86a 100644 (file)
--- a/test/CodeGen/Thumb2/2010-06-21-TailMergeBug.ll
+++ b/test/CodeGen/Thumb2/2010-06-21-TailMergeBug.ll
@@ -32,15 +32,15 @@
 
 define fastcc i32 @parse_percent_token() nounwind {
 entry:
-; CHECK: ittt eq
-; CHECK: ittt eq
-; CHECK: ittt eq
-; CHECK: ittt eq
-; CHECK: ittt eq
-; CHECK: moveq r0
-; CHECK-NOT: LBB0_
-; CHECK: ldreq
-; CHECK: popeq
+; CHECK: pop
+; CHECK: pop
+; CHECK: pop
+; CHECK: pop
+; CHECK: pop
+; CHECK: pop
+; CHECK: pop
+; Do not convert into single stream code. BranchProbability Analysis assumes
+; that branches which goes to "ret" intruction have lower probabilities.
   switch i32 undef, label %bb7 [
     i32 37, label %bb43
     i32 48, label %bb5

diff --git a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
index a4035bb8ed491eb7df7dc5116e622d273b970a7e..af8fcc64124706ad448cc5b59180f03faa9546e4 100644 (file)
--- a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
+++ b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
@@ -21,13 +21,13 @@ cond_next:
        ret i32 %tmp15
 }
 
-; FIXME: Check for # of unconditional branch after adding branch folding post ifcvt.
 define i32 @t2(i32 %a, i32 %b) nounwind {
 entry:
+; Do not if-convert when branches go to the different loops.
 ; CHECK: t2:
-; CHECK: ite gt
-; CHECK: subgt
-; CHECK: suble
+; CHECK-NOT: ite gt
+; CHECK-NOT: subgt
+; CHECK-NOT: suble
        %tmp1434 = icmp eq i32 %a, %b           ; <i1> [#uses=1]
        br i1 %tmp1434, label %bb17, label %bb.outer