diff options
author | Dan Gohman <gohman@apple.com> | 2009-10-07 17:38:06 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2009-10-07 17:38:06 +0000 |
commit | e33f44cfc547359bc28526e4c5e1852b600b4448 (patch) | |
tree | d809153a8332a1292de9f01eb8cf5cfbead8297e /lib/CodeGen | |
parent | 2dbc4c84f6de55deeea6631201c5df943d5327c0 (diff) | |
download | external_llvm-e33f44cfc547359bc28526e4c5e1852b600b4448.zip external_llvm-e33f44cfc547359bc28526e4c5e1852b600b4448.tar.gz external_llvm-e33f44cfc547359bc28526e4c5e1852b600b4448.tar.bz2 |
Replace TargetInstrInfo::isInvariantLoad and its target-specific
implementations with a new MachineInstr::isInvariantLoad, which uses
MachineMemOperands and is target-independent. This brings MachineLICM
and other functionality to targets which previously lacked an
isInvariantLoad implementation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83475 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen')
-rw-r--r-- | lib/CodeGen/MachineInstr.cpp | 43 | ||||
-rw-r--r-- | lib/CodeGen/MachineLICM.cpp | 8 | ||||
-rw-r--r-- | lib/CodeGen/MachineSink.cpp | 2 | ||||
-rw-r--r-- | lib/CodeGen/ScheduleDAGInstrs.cpp | 2 |
4 files changed, 48 insertions, 7 deletions
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp index a3560a7..2dc99f5 100644 --- a/lib/CodeGen/MachineInstr.cpp +++ b/lib/CodeGen/MachineInstr.cpp @@ -24,6 +24,7 @@ #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetInstrDesc.h" #include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/DebugInfo.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/LeakDetector.h" @@ -946,7 +947,7 @@ bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII, // destination. The check for isInvariantLoad gives the targe the chance to // classify the load as always returning a constant, e.g. a constant pool // load. - if (TID->mayLoad() && !TII->isInvariantLoad(this)) + if (TID->mayLoad() && !isInvariantLoad()) // Otherwise, this is a real load. If there is a store between the load and // end of block, or if the load is volatile, we can't move it. return !SawStore && !hasVolatileMemoryRef(); @@ -1005,6 +1006,46 @@ bool MachineInstr::hasVolatileMemoryRef() const { return false; } +/// isInvariantLoad - Return true if this instruction is loading from a +/// location whose value is invariant across the function. For example, +/// loading a value from the constant pool or from from the argument area +/// of a function if it does not change. This should only return true of +/// *all* loads the instruction does are invariant (if it does multiple loads). +bool MachineInstr::isInvariantLoad(AliasAnalysis *AA) const { + // If the instruction doesn't load at all, it isn't an invariant load. + if (!TID->mayLoad()) + return false; + + // If the instruction has lost its memoperands, conservatively assume that + // it may not be an invariant load. + if (memoperands_empty()) + return false; + + const MachineFrameInfo *MFI = getParent()->getParent()->getFrameInfo(); + + for (mmo_iterator I = memoperands_begin(), + E = memoperands_end(); I != E; ++I) { + if ((*I)->isVolatile()) return false; + if ((*I)->isStore()) return false; + + if (const Value *V = (*I)->getValue()) { + // A load from a constant PseudoSourceValue is invariant. + if (const PseudoSourceValue *PSV = dyn_cast<PseudoSourceValue>(V)) + if (PSV->isConstant(MFI)) + continue; + // If we have an AliasAnalysis, ask it whether the memory is constant. + if (AA && AA->pointsToConstantMemory(V)) + continue; + } + + // Otherwise assume conservatively. + return false; + } + + // Everything checks out. + return true; +} + void MachineInstr::dump() const { errs() << " " << *this; } diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp index 61678f1..b5827aa 100644 --- a/lib/CodeGen/MachineLICM.cpp +++ b/lib/CodeGen/MachineLICM.cpp @@ -28,6 +28,7 @@ #include "llvm/Target/TargetRegisterInfo.h" #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetMachine.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/Statistic.h" #include "llvm/Support/Compiler.h" @@ -47,6 +48,7 @@ namespace { BitVector AllocatableSet; // Various analyses that we use... + AliasAnalysis *AA; // Alias analysis info. MachineLoopInfo *LI; // Current MachineLoopInfo MachineDominatorTree *DT; // Machine dominator tree for the cur loop MachineRegisterInfo *RegInfo; // Machine register information @@ -72,6 +74,7 @@ namespace { AU.setPreservesCFG(); AU.addRequired<MachineLoopInfo>(); AU.addRequired<MachineDominatorTree>(); + AU.addRequired<AliasAnalysis>(); AU.addPreserved<MachineLoopInfo>(); AU.addPreserved<MachineDominatorTree>(); MachineFunctionPass::getAnalysisUsage(AU); @@ -144,6 +147,7 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) { // Get our Loop information... LI = &getAnalysis<MachineLoopInfo>(); DT = &getAnalysis<MachineDominatorTree>(); + AA = &getAnalysis<AliasAnalysis>(); for (MachineLoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) { @@ -214,7 +218,7 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) { // Okay, this instruction does a load. As a refinement, we allow the target // to decide whether the loaded value is actually a constant. If so, we can // actually use it as a load. - if (!TII->isInvariantLoad(&I)) + if (!I.isInvariantLoad(AA)) // FIXME: we should be able to sink loads with no other side effects if // there is nothing that can change memory from here until the end of // block. This is a trivial form of alias analysis. @@ -259,8 +263,6 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) { // Don't hoist an instruction that uses or defines a physical register. if (TargetRegisterInfo::isPhysicalRegister(Reg)) { - // If this is a physical register use, we can't move it. If it is a def, - // we can move it, but only if the def is dead. if (MO.isUse()) { // If the physreg has no defs anywhere, it's just an ambient register // and we can freely move its uses. Alternatively, if it's allocatable, diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp index 636dad8..e5c3420 100644 --- a/lib/CodeGen/MachineSink.cpp +++ b/lib/CodeGen/MachineSink.cpp @@ -178,8 +178,6 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) { if (Reg == 0) continue; if (TargetRegisterInfo::isPhysicalRegister(Reg)) { - // If this is a physical register use, we can't move it. If it is a def, - // we can move it, but only if the def is dead. if (MO.isUse()) { // If the physreg has no defs anywhere, it's just an ambient register // and we can freely move its uses. Alternatively, if it's allocatable, diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp index b55e606..f50844f 100644 --- a/lib/CodeGen/ScheduleDAGInstrs.cpp +++ b/lib/CodeGen/ScheduleDAGInstrs.cpp @@ -375,7 +375,7 @@ void ScheduleDAGInstrs::BuildSchedGraph() { // Treat all other stores conservatively. goto new_chain; } else if (TID.mayLoad()) { - if (TII->isInvariantLoad(MI)) { + if (MI->isInvariantLoad()) { // Invariant load, no chain dependencies needed! } else if (const Value *V = getUnderlyingObjectForInstr(MI)) { // A load from a specific PseudoSourceValue. Add precise dependencies. |