[llvm] r200431 - PGO branch weight: update edge weights in SelectionDAGBuilder.
Manman Ren
manman.ren at gmail.com
Wed Jan 29 16:58:37 PST 2014
I ran the tests on my local machine, it worked fine.
I will revert this commit.
Manman
On Wed, Jan 29, 2014 at 4:56 PM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:
> Looks like this broke test/CodeGen/ARM/lsr-unfolded-offset.ll.
>
> On 29 January 2014 19:24, Manman Ren <manman.ren at gmail.com> wrote:
> > Author: mren
> > Date: Wed Jan 29 18:24:37 2014
> > New Revision: 200431
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=200431&view=rev
> > Log:
> > PGO branch weight: update edge weights in SelectionDAGBuilder.
> >
> > When converting from "or + br" to two branches, or converting from
> > "and + br" to two branches, we correctly update the edge weights of
> > the two branches.
> >
> > Added:
> > llvm/trunk/test/CodeGen/X86/MachineBranchProb.ll
> > Modified:
> > llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> > llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
> >
> > Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=200431&r1=200430&r2=200431&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> (original)
> > +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Wed Jan
> 29 18:24:37 2014
> > @@ -1393,7 +1393,9 @@ SelectionDAGBuilder::EmitBranchForMerged
> > MachineBasicBlock
> *TBB,
> > MachineBasicBlock
> *FBB,
> > MachineBasicBlock
> *CurBB,
> > - MachineBasicBlock
> *SwitchBB) {
> > + MachineBasicBlock
> *SwitchBB,
> > + uint32_t TWeight,
> > + uint32_t FWeight) {
> > const BasicBlock *BB = CurBB->getBasicBlock();
> >
> > // If the leaf of the tree is a comparison, merge the condition into
> > @@ -1418,7 +1420,7 @@ SelectionDAGBuilder::EmitBranchForMerged
> > }
> >
> > CaseBlock CB(Condition, BOp->getOperand(0),
> > - BOp->getOperand(1), NULL, TBB, FBB, CurBB);
> > + BOp->getOperand(1), NULL, TBB, FBB, CurBB, TWeight,
> FWeight);
> > SwitchCases.push_back(CB);
> > return;
> > }
> > @@ -1426,17 +1428,26 @@ SelectionDAGBuilder::EmitBranchForMerged
> >
> > // Create a CaseBlock record representing this branch.
> > CaseBlock CB(ISD::SETEQ, Cond,
> ConstantInt::getTrue(*DAG.getContext()),
> > - NULL, TBB, FBB, CurBB);
> > + NULL, TBB, FBB, CurBB, TWeight, FWeight);
> > SwitchCases.push_back(CB);
> > }
> >
> > +/// Scale down both weights to fit into uint32_t.
> > +static void ScaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
> > + uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
> > + uint32_t Scale = (NewMax / UINT32_MAX) + 1;
> > + NewTrue = NewTrue / Scale;
> > + NewFalse = NewFalse / Scale;
> > +}
> > +
> > /// FindMergedConditions - If Cond is an expression like
> > void SelectionDAGBuilder::FindMergedConditions(const Value *Cond,
> > MachineBasicBlock *TBB,
> > MachineBasicBlock *FBB,
> > MachineBasicBlock *CurBB,
> > MachineBasicBlock
> *SwitchBB,
> > - unsigned Opc) {
> > + unsigned Opc, uint32_t
> TWeight,
> > + uint32_t FWeight) {
> > // If this node is not part of the or/and tree, emit it as a branch.
> > const Instruction *BOp = dyn_cast<Instruction>(Cond);
> > if (!BOp || !(isa<BinaryOperator>(BOp) || isa<CmpInst>(BOp)) ||
> > @@ -1444,7 +1455,8 @@ void SelectionDAGBuilder::FindMergedCond
> > BOp->getParent() != CurBB->getBasicBlock() ||
> > !InBlock(BOp->getOperand(0), CurBB->getBasicBlock()) ||
> > !InBlock(BOp->getOperand(1), CurBB->getBasicBlock())) {
> > - EmitBranchForMergedCondition(Cond, TBB, FBB, CurBB, SwitchBB);
> > + EmitBranchForMergedCondition(Cond, TBB, FBB, CurBB, SwitchBB,
> > + TWeight, FWeight);
> > return;
> > }
> >
> > @@ -1456,6 +1468,7 @@ void SelectionDAGBuilder::FindMergedCond
> >
> > if (Opc == Instruction::Or) {
> > // Codegen X | Y as:
> > + // BB1:
> > // jmp_if_X TBB
> > // jmp TmpBB
> > // TmpBB:
> > @@ -1463,14 +1476,34 @@ void SelectionDAGBuilder::FindMergedCond
> > // jmp FBB
> > //
> >
> > + // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
> > + // The requirement is that
> > + // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
> > + // = TrueProb for orignal BB.
> > + // Assuming the orignal weights are A and B, one choice is to set
> BB1's
> > + // weights to A and A+2B, and set TmpBB's weights to A and 2B. This
> choice
> > + // assumes that
> > + // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
> > + // Another choice is to assume TrueProb for BB1 equals to TrueProb
> for
> > + // TmpBB, but the math is more complicated.
> > +
> > + uint64_t NewTrueWeight = TWeight;
> > + uint64_t NewFalseWeight = (uint64_t)TWeight + 2 * (uint64_t)FWeight;
> > + ScaleWeights(NewTrueWeight, NewFalseWeight);
> > // Emit the LHS condition.
> > - FindMergedConditions(BOp->getOperand(0), TBB, TmpBB, CurBB,
> SwitchBB, Opc);
> > + FindMergedConditions(BOp->getOperand(0), TBB, TmpBB, CurBB,
> SwitchBB, Opc,
> > + NewTrueWeight, NewFalseWeight);
> >
> > + NewTrueWeight = TWeight;
> > + NewFalseWeight = 2 * (uint64_t)FWeight;
> > + ScaleWeights(NewTrueWeight, NewFalseWeight);
> > // Emit the RHS condition into TmpBB.
> > - FindMergedConditions(BOp->getOperand(1), TBB, FBB, TmpBB, SwitchBB,
> Opc);
> > + FindMergedConditions(BOp->getOperand(1), TBB, FBB, TmpBB, SwitchBB,
> Opc,
> > + NewTrueWeight, NewFalseWeight);
> > } else {
> > assert(Opc == Instruction::And && "Unknown merge op!");
> > // Codegen X & Y as:
> > + // BB1:
> > // jmp_if_X TmpBB
> > // jmp FBB
> > // TmpBB:
> > @@ -1479,11 +1512,28 @@ void SelectionDAGBuilder::FindMergedCond
> > //
> > // This requires creation of TmpBB after CurBB.
> >
> > + // We have flexibility in setting Prob for BB1 and Prob for TmpBB.
> > + // The requirement is that
> > + // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
> > + // = FalseProb for orignal BB.
> > + // Assuming the orignal weights are A and B, one choice is to set
> BB1's
> > + // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This
> choice
> > + // assumes that
> > + // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
> > +
> > + uint64_t NewTrueWeight = 2 * (uint64_t)TWeight + (uint64_t)FWeight;
> > + uint64_t NewFalseWeight = FWeight;
> > + ScaleWeights(NewTrueWeight, NewFalseWeight);
> > // Emit the LHS condition.
> > - FindMergedConditions(BOp->getOperand(0), TmpBB, FBB, CurBB,
> SwitchBB, Opc);
> > + FindMergedConditions(BOp->getOperand(0), TmpBB, FBB, CurBB,
> SwitchBB, Opc,
> > + NewTrueWeight, NewFalseWeight);
> >
> > + NewTrueWeight = 2 * (uint64_t)TWeight;
> > + NewFalseWeight = FWeight;
> > + ScaleWeights(NewTrueWeight, NewFalseWeight);
> > // Emit the RHS condition into TmpBB.
> > - FindMergedConditions(BOp->getOperand(1), TBB, FBB, TmpBB, SwitchBB,
> Opc);
> > + FindMergedConditions(BOp->getOperand(1), TBB, FBB, TmpBB, SwitchBB,
> Opc,
> > + NewTrueWeight, NewFalseWeight);
> > }
> > }
> >
> > @@ -1570,7 +1620,8 @@ void SelectionDAGBuilder::visitBr(const
> > (BOp->getOpcode() == Instruction::And ||
> > BOp->getOpcode() == Instruction::Or)) {
> > FindMergedConditions(BOp, Succ0MBB, Succ1MBB, BrMBB, BrMBB,
> > - BOp->getOpcode());
> > + BOp->getOpcode(), getEdgeWeight(BrMBB,
> Succ0MBB),
> > + getEdgeWeight(BrMBB, Succ1MBB));
> > // If the compares in later blocks need to use values not
> currently
> > // exported from this block, export them now. This block should
> always
> > // be the first entry.
> >
> > Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=200431&r1=200430&r2=200431&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
> > +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Wed Jan 29
> 18:24:37 2014
> > @@ -612,11 +612,13 @@ public:
> >
> > void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB,
> > MachineBasicBlock *FBB, MachineBasicBlock
> *CurBB,
> > - MachineBasicBlock *SwitchBB, unsigned Opc);
> > + MachineBasicBlock *SwitchBB, unsigned Opc,
> > + uint32_t TW, uint32_t FW);
> > void EmitBranchForMergedCondition(const Value *Cond,
> MachineBasicBlock *TBB,
> > MachineBasicBlock *FBB,
> > MachineBasicBlock *CurBB,
> > - MachineBasicBlock *SwitchBB);
> > + MachineBasicBlock *SwitchBB,
> > + uint32_t TW, uint32_t FW);
> > bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
> > bool isExportableFromCurrentBlock(const Value *V, const BasicBlock
> *FromBB);
> > void CopyToExportRegsIfNeeded(const Value *V);
> >
> > Added: llvm/trunk/test/CodeGen/X86/MachineBranchProb.ll
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/MachineBranchProb.ll?rev=200431&view=auto
> >
> ==============================================================================
> > --- llvm/trunk/test/CodeGen/X86/MachineBranchProb.ll (added)
> > +++ llvm/trunk/test/CodeGen/X86/MachineBranchProb.ll Wed Jan 29 18:24:37
> 2014
> > @@ -0,0 +1,34 @@
> > +; RUN: llc < %s -mtriple=x86_64-apple-darwin
> -print-machineinstrs=expand-isel-pseudos -o /dev/null 2>&1 | FileCheck %s
> > +
> > +;; Make sure a transformation in SelectionDAGBuilder that converts "or
> + br" to
> > +;; two branches correctly updates the branch probability.
> > +
> > + at max_regno = common global i32 0, align 4
> > +
> > +define void @test(i32* %old, i32 %final) {
> > +for.cond:
> > + br label %for.cond2
> > +
> > +for.cond2: ; preds = %for.inc,
> %for.cond
> > + %i.1 = phi i32 [ %inc19, %for.inc ], [ 0, %for.cond ]
> > + %bit.0 = phi i32 [ %shl, %for.inc ], [ 1, %for.cond ]
> > + %tobool = icmp eq i32 %bit.0, 0
> > + %v3 = load i32* @max_regno, align 4
> > + %cmp4 = icmp eq i32 %i.1, %v3
> > + %or.cond = or i1 %tobool, %cmp4
> > + br i1 %or.cond, label %for.inc20, label %for.inc, !prof !0
> > +; CHECK: BB#1: derived from LLVM BB %for.cond2
> > +; CHECK: Successors according to CFG: BB#3(28004359) BB#4(1101746182)
> > +; CHECK: BB#4: derived from LLVM BB %for.cond2
> > +; CHECK: Successors according to CFG: BB#3(56008718) BB#2(2147483647)
> > +
> > +for.inc: ; preds = %for.cond2
> > + %shl = shl i32 %bit.0, 1
> > + %inc19 = add nsw i32 %i.1, 1
> > + br label %for.cond2
> > +
> > +for.inc20: ; preds = %for.cond2
> > + ret void
> > +}
> > +
> > +!0 = metadata !{metadata !"branch_weights", i32 112017436, i32
> -735157296}
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
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