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Pass edges weights to MachineBasicBlock::addSuccessor in TailDuplicatePass to

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preserve branch probability information.

<rdar://problem/15893208>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201245 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Akira Hatanaka 2014-02-12 18:09:18 +00:00
parent e4c62d1034
commit 386fedd32e
2 changed files with 66 additions and 2 deletions
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16
lib/CodeGen/TailDuplication.cpp
View File

@ -19,6 +19,7 @@
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
@ -61,6 +62,7 @@ namespace {
class TailDuplicatePass : public MachineFunctionPass {
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
const MachineBranchProbabilityInfo *MBPI;
MachineModuleInfo *MMI;
MachineRegisterInfo *MRI;
OwningPtr<RegScavenger> RS;
@ -80,6 +82,8 @@ namespace {
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
private:
void AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
MachineBasicBlock *BB);
@ -132,6 +136,8 @@ bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
TRI = MF.getTarget().getRegisterInfo();
MRI = &MF.getRegInfo();
MMI = getAnalysisIfAvailable<MachineModuleInfo>();
MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
PreRegAlloc = MRI->isSSA();
RS.reset();
if (MRI->tracksLiveness() && TRI->trackLivenessAfterRegAlloc(MF))
@ -144,6 +150,11 @@ bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
return MadeChange;
}
void TailDuplicatePass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<MachineBranchProbabilityInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) {
for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = I;
@ -721,11 +732,12 @@ TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
if (PredTBB)
TII->InsertBranch(*PredBB, PredTBB, PredFBB, PredCond, DebugLoc());
uint32_t Weight = MBPI->getEdgeWeight(PredBB, TailBB);
PredBB->removeSuccessor(TailBB);
unsigned NumSuccessors = PredBB->succ_size();
assert(NumSuccessors <= 1);
if (NumSuccessors == 0 || *PredBB->succ_begin() != NewTarget)
PredBB->addSuccessor(NewTarget);
PredBB->addSuccessor(NewTarget, Weight);
TDBBs.push_back(PredBB);
}
@ -836,7 +848,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
"TailDuplicate called on block with multiple successors!");
for (MachineBasicBlock::succ_iterator I = TailBB->succ_begin(),
E = TailBB->succ_end(); I != E; ++I)
PredBB->addSuccessor(*I);
PredBB->addSuccessor(*I, MBPI->getEdgeWeight(TailBB, I));
Changed = true;
++NumTailDups;

52
test/CodeGen/ARM/taildup-branch-weight.ll Normal file
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@ -0,0 +1,52 @@
; RUN: llc < %s -march=arm -print-machineinstrs=tailduplication -tail-dup-size=100 -enable-tail-merge=false -disable-cgp -o /dev/null 2>&1 | FileCheck %s
; CHECK: Machine code for function test0:
; CHECK: Successors according to CFG: BB#1(4) BB#2(124)
define void @test0(i32 %a, i32 %b, i32* %c, i32* %d) {
entry:
store i32 3, i32* %d
br label %B1
B2:
store i32 2, i32* %c
br label %B4
B3:
store i32 2, i32* %c
br label %B4
B1:
store i32 1, i32* %d
%test0 = icmp slt i32 %a, %b
br i1 %test0, label %B2, label %B3, !prof !0
B4:
ret void
}
!0 = metadata !{metadata !"branch_weights", i32 4, i32 124}
; CHECK: Machine code for function test1:
; CHECK: Successors according to CFG: BB#1(8) BB#2(248)
@g0 = common global i32 0, align 4
define void @test1(i32 %a, i32 %b, i32* %c, i32* %d, i32* %e) {
%test0 = icmp slt i32 %a, %b
br i1 %test0, label %B1, label %B2, !prof !1
B1:
br label %B3
B2:
store i32 2, i32* %c
br label %B3
B3:
store i32 3, i32* %e
ret void
}
!1 = metadata !{metadata !"branch_weights", i32 248, i32 8}