[llvm-commits] [llvm] r106066 - in /llvm/trunk: lib/CodeGen/MachineSink.cpp lib/Target/X86/X86ISelLowering.cpp test/CodeGen/X86/MachineSink-CritEdge.ll
Daniel Dunbar
daniel at zuster.org
Tue Jun 22 17:49:14 PDT 2010
On Tue, Jun 22, 2010 at 5:45 PM, Daniel Dunbar <daniel at zuster.org> wrote:
> Hi Bill,
>
> It looks like bzip2 is being miscompiled with this commit in, I
> reverted it in r106610.
Err, r106614 that should read.
- Daniel
>
> Can you take a look?
>
> - Daniel
>
> On Tue, Jun 15, 2010 at 4:46 PM, Bill Wendling <isanbard at gmail.com> wrote:
>> Author: void
>> Date: Tue Jun 15 18:46:31 2010
>> New Revision: 106066
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=106066&view=rev
>> Log:
>> Create a more targeted fix for not sinking instructions into a range where it
>> will conflict with another live range. The place which creates this scenerio is
>> the code in X86 that lowers a select instruction by splitting the MBBs. This
>> eliminates the need to check from the bottom up in an MBB for live pregs.
>>
>>
>> Modified:
>> llvm/trunk/lib/CodeGen/MachineSink.cpp
>> llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>> llvm/trunk/test/CodeGen/X86/MachineSink-CritEdge.ll
>>
>> Modified: llvm/trunk/lib/CodeGen/MachineSink.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineSink.cpp?rev=106066&r1=106065&r2=106066&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/MachineSink.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/MachineSink.cpp Tue Jun 15 18:46:31 2010
>> @@ -25,7 +25,6 @@
>> #include "llvm/Target/TargetRegisterInfo.h"
>> #include "llvm/Target/TargetInstrInfo.h"
>> #include "llvm/Target/TargetMachine.h"
>> -#include "llvm/ADT/SmallSet.h"
>> #include "llvm/ADT/Statistic.h"
>> #include "llvm/Support/Debug.h"
>> #include "llvm/Support/raw_ostream.h"
>> @@ -62,7 +61,6 @@
>> bool ProcessBlock(MachineBasicBlock &MBB);
>> bool SinkInstruction(MachineInstr *MI, bool &SawStore);
>> bool AllUsesDominatedByBlock(unsigned Reg, MachineBasicBlock *MBB) const;
>> - bool LiveOutOfBasicBlock(const MachineInstr *MI, unsigned Reg) const;
>> };
>> } // end anonymous namespace
>>
>> @@ -168,44 +166,6 @@
>> return MadeChange;
>> }
>>
>> -/// LiveOutOfBasicBlock - Determine if the physical register, defined and dead
>> -/// in MI, is live on exit from the basic block.
>> -bool MachineSinking::LiveOutOfBasicBlock(const MachineInstr *MI,
>> - unsigned Reg) const {
>> - assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
>> - "Only want to determine if a physical register is live out of a BB!");
>> -
>> - const MachineBasicBlock *MBB = MI->getParent();
>> - SmallSet<unsigned, 8> KilledRegs;
>> - MachineBasicBlock::const_iterator I = MBB->end();
>> - MachineBasicBlock::const_iterator E = MBB->begin();
>> - assert(I != E && "How can there be an empty block at this point?!");
>> -
>> - // Loop through the instructions bottom-up. If we see a kill of the preg
>> - // first, then it's not live out of the BB. If we see a use or def first, then
>> - // we assume that it is live out of the BB.
>> - do {
>> - const MachineInstr &CurMI = *--I;
>> -
>> - for (unsigned i = 0, e = CurMI.getNumOperands(); i != e; ++i) {
>> - const MachineOperand &MO = CurMI.getOperand(i);
>> - if (!MO.isReg()) continue; // Ignore non-register operands.
>> -
>> - unsigned MOReg = MO.getReg();
>> - if (MOReg == 0) continue;
>> -
>> - if (MOReg == Reg) {
>> - if (MO.isKill())
>> - return false;
>> - if (MO.isUse() || MO.isDef())
>> - return true;
>> - }
>> - }
>> - } while (I != E);
>> -
>> - return false;
>> -}
>> -
>> /// SinkInstruction - Determine whether it is safe to sink the specified machine
>> /// instruction out of its current block into a successor.
>> bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
>> @@ -228,7 +188,6 @@
>> // SuccToSinkTo - This is the successor to sink this instruction to, once we
>> // decide.
>> MachineBasicBlock *SuccToSinkTo = 0;
>> - SmallVector<unsigned, 4> PhysRegs;
>>
>> for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
>> const MachineOperand &MO = MI->getOperand(i);
>> @@ -257,12 +216,9 @@
>> if (AllocatableSet.test(AliasReg))
>> return false;
>> }
>> - } else {
>> - if (!MO.isDead())
>> - // A def that isn't dead. We can't move it.
>> - return false;
>> - else
>> - PhysRegs.push_back(Reg);
>> + } else if (!MO.isDead()) {
>> + // A def that isn't dead. We can't move it.
>> + return false;
>> }
>> } else {
>> // Virtual register uses are always safe to sink.
>> @@ -329,10 +285,14 @@
>> // If the instruction to move defines a dead physical register which is live
>> // when leaving the basic block, don't move it because it could turn into a
>> // "zombie" define of that preg. E.g., EFLAGS. (<rdar://problem/8030636>)
>> - for (SmallVectorImpl<unsigned>::const_iterator
>> - I = PhysRegs.begin(), E = PhysRegs.end(); I != E; ++I)
>> - if (LiveOutOfBasicBlock(MI, *I))
>> + for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
>> + const MachineOperand &MO = MI->getOperand(I);
>> + if (!MO.isReg()) continue;
>> + unsigned Reg = MO.getReg();
>> + if (Reg == 0 || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
>> + if (SuccToSinkTo->isLiveIn(Reg))
>> return false;
>> + }
>>
>> DEBUG(dbgs() << "Sink instr " << *MI << "\tinto block " << *SuccToSinkTo);
>>
>>
>> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=106066&r1=106065&r2=106066&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue Jun 15 18:46:31 2010
>> @@ -8465,22 +8465,42 @@
>> MachineBasicBlock *sinkMBB = F->CreateMachineBasicBlock(LLVM_BB);
>> unsigned Opc =
>> X86::GetCondBranchFromCond((X86::CondCode)MI->getOperand(3).getImm());
>> +
>> BuildMI(BB, DL, TII->get(Opc)).addMBB(sinkMBB);
>> F->insert(It, copy0MBB);
>> F->insert(It, sinkMBB);
>> +
>> // Update machine-CFG edges by first adding all successors of the current
>> // block to the new block which will contain the Phi node for the select.
>> for (MachineBasicBlock::succ_iterator I = BB->succ_begin(),
>> E = BB->succ_end(); I != E; ++I)
>> sinkMBB->addSuccessor(*I);
>> +
>> // Next, remove all successors of the current block, and add the true
>> // and fallthrough blocks as its successors.
>> while (!BB->succ_empty())
>> BB->removeSuccessor(BB->succ_begin());
>> +
>> // Add the true and fallthrough blocks as its successors.
>> BB->addSuccessor(copy0MBB);
>> BB->addSuccessor(sinkMBB);
>>
>> + // If the EFLAGS register isn't dead in the terminator, then claim that it's
>> + // live into the sink and copy blocks.
>> + const MachineFunction *MF = BB->getParent();
>> + const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
>> + BitVector ReservedRegs = TRI->getReservedRegs(*MF);
>> + const MachineInstr *Term = BB->getFirstTerminator();
>> +
>> + for (unsigned I = 0, E = Term->getNumOperands(); I != E; ++I) {
>> + const MachineOperand &MO = Term->getOperand(I);
>> + if (!MO.isReg() || MO.isKill() || MO.isDead()) continue;
>> + unsigned Reg = MO.getReg();
>> + if (Reg != X86::EFLAGS) continue;
>> + copy0MBB->addLiveIn(Reg);
>> + sinkMBB->addLiveIn(Reg);
>> + }
>> +
>> // copy0MBB:
>> // %FalseValue = ...
>> // # fallthrough to sinkMBB
>>
>> Modified: llvm/trunk/test/CodeGen/X86/MachineSink-CritEdge.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/MachineSink-CritEdge.ll?rev=106066&r1=106065&r2=106066&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/MachineSink-CritEdge.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/MachineSink-CritEdge.ll Tue Jun 15 18:46:31 2010
>> @@ -1,10 +1,4 @@
>> ; RUN: llc < %s | FileCheck %s
>> -; XFAIL: *
>> -;
>> -; See <rdar://problem/8030636>. This test isn't valid after we made machine
>> -; sinking more conservative about sinking instructions that define a preg into a
>> -; block when we don't know if the preg is killed within the current block.
>> -
>> target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
>> target triple = "x86_64-apple-darwin10.0.0"
>>
>>
>>
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>
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