class TargetMachine;
class TargetRegisterClass;
class TargetRegisterInfo;
+class LoadInst;
/// FastISel - This is a fast-path instruction selection class that
/// generates poor code and doesn't support illegal types or non-trivial
/// index value.
std::pair<unsigned, bool> getRegForGEPIndex(const Value *V);
- /// recomputeInsertPt - Reset InsertPt to prepare for insterting instructions
+ /// TryToFoldLoad - The specified machine instr operand is a vreg, and that
+ /// vreg is being provided by the specified load instruction. If possible,
+ /// try to fold the load as an operand to the instruction, returning true if
+ /// possible.
+ virtual bool TryToFoldLoad(MachineInstr * /*MI*/, unsigned /*OpNo*/,
+ const LoadInst * /*LI*/) {
+ return false;
+ }
+
+ /// recomputeInsertPt - Reset InsertPt to prepare for inserting instructions
/// into the current block.
void recomputeInsertPt();
class ScheduleHazardRecognizer;
class GCFunctionInfo;
class ScheduleDAGSDNodes;
+ class LoadInst;
/// SelectionDAGISel - This is the common base class used for SelectionDAG-based
/// pattern-matching instruction selectors.
void PrepareEHLandingPad();
void SelectAllBasicBlocks(const Function &Fn);
+ bool TryToFoldFastISelLoad(const LoadInst *LI, FastISel *FastIS);
void FinishBasicBlock();
void SelectBasicBlock(BasicBlock::const_iterator Begin,
}
}
+
+
+
+bool SelectionDAGISel::TryToFoldFastISelLoad(const LoadInst *LI,
+ FastISel *FastIS) {
+ // Don't try to fold volatile loads. Target has to deal with alignment
+ // constraints.
+ if (LI->isVolatile()) return false;
+
+ // Figure out which vreg this is going into.
+ unsigned LoadReg = FastIS->getRegForValue(LI);
+ assert(LoadReg && "Load isn't already assigned a vreg? ");
+
+ // Check to see what the uses of this vreg are. If it has no uses, or more
+ // than one use (at the machine instr level) then we can't fold it.
+ MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(LoadReg);
+ if (RI == RegInfo->reg_end())
+ return false;
+
+ // See if there is exactly one use of the vreg. If there are multiple uses,
+ // then the instruction got lowered to multiple machine instructions or the
+ // use of the loaded value ended up being multiple operands of the result, in
+ // either case, we can't fold this.
+ MachineRegisterInfo::reg_iterator PostRI = RI; ++PostRI;
+ if (PostRI != RegInfo->reg_end())
+ return false;
+
+ assert(RI.getOperand().isUse() &&
+ "The only use of the vreg must be a use, we haven't emitted the def!");
+
+ // Ask the target to try folding the load.
+ return FastIS->TryToFoldLoad(&*RI, RI.getOperandNo(), LI);
+}
+
+
+
+
void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
// Initialize the Fast-ISel state, if needed.
FastISel *FastIS = 0;
FastIS->recomputeInsertPt();
// Try to select the instruction with FastISel.
- if (FastIS->SelectInstruction(Inst))
+ if (FastIS->SelectInstruction(Inst)) {
+ // If fast isel succeeded, check to see if there is a single-use
+ // non-volatile load right before the selected instruction, and see if
+ // the load is used by the instruction. If so, try to fold it.
+ const Instruction *BeforeInst = 0;
+ if (Inst != Begin)
+ BeforeInst = llvm::prior(llvm::prior(BI));
+ if (BeforeInst && isa<LoadInst>(BeforeInst) &&
+ BeforeInst->hasOneUse() && *BeforeInst->use_begin() == Inst &&
+ TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), FastIS)) {
+ // If we succeeded, don't re-select the load.
+ --BI;
+ }
continue;
+ }
// Then handle certain instructions as single-LLVM-Instruction blocks.
if (isa<CallInst>(Inst)) {
virtual bool TargetSelectInstruction(const Instruction *I);
+ /// TryToFoldLoad - The specified machine instr operand is a vreg, and that
+ /// vreg is being provided by the specified load instruction. If possible,
+ /// try to fold the load as an operand to the instruction, returning true if
+ /// possible.
+ virtual bool TryToFoldLoad(MachineInstr *MI, unsigned OpNo,
+ const LoadInst *LI);
+
#include "X86GenFastISel.inc"
private:
return ResultReg;
}
+/// TryToFoldLoad - The specified machine instr operand is a vreg, and that
+/// vreg is being provided by the specified load instruction. If possible,
+/// try to fold the load as an operand to the instruction, returning true if
+/// possible.
+bool X86FastISel::TryToFoldLoad(MachineInstr *MI, unsigned OpNo,
+ const LoadInst *LI) {
+ X86AddressMode AM;
+ if (!X86SelectAddress(LI->getOperand(0), AM))
+ return false;
+
+ X86InstrInfo &XII = (X86InstrInfo&)TII;
+
+ unsigned Size = TD.getTypeAllocSize(LI->getType());
+ unsigned Alignment = LI->getAlignment();
+
+ SmallVector<MachineOperand, 8> AddrOps;
+ AM.getFullAddress(AddrOps);
+
+ MachineInstr *Result =
+ XII.foldMemoryOperandImpl(*FuncInfo.MF, MI, OpNo, AddrOps, Size, Alignment);
+ if (Result == 0) return false;
+
+ MI->getParent()->insert(MI, Result);
+ MI->eraseFromParent();
+ return true;
+}
+
+
namespace llvm {
llvm::FastISel *X86::createFastISel(FunctionLoweringInfo &funcInfo) {
return new X86FastISel(funcInfo);
: BaseType(RegBase), Scale(1), IndexReg(0), Disp(0), GV(0), GVOpFlags(0) {
Base.Reg = 0;
}
+
+
+ void getFullAddress(SmallVectorImpl<MachineOperand> &MO) {
+ assert(Scale == 1 || Scale == 2 || Scale == 4 || Scale == 8);
+
+ if (BaseType == X86AddressMode::RegBase)
+ MO.push_back(MachineOperand::CreateReg(Base.Reg, false, false,
+ false, false, false, 0, false));
+ else {
+ assert(BaseType == X86AddressMode::FrameIndexBase);
+ MO.push_back(MachineOperand::CreateFI(Base.FrameIndex));
+ }
+
+ MO.push_back(MachineOperand::CreateImm(Scale));
+ MO.push_back(MachineOperand::CreateReg(IndexReg, false, false,
+ false, false, false, 0, false));
+
+ if (GV)
+ MO.push_back(MachineOperand::CreateGA(GV, Disp, GVOpFlags));
+ else
+ MO.push_back(MachineOperand::CreateImm(Disp));
+
+ MO.push_back(MachineOperand::CreateReg(0, false, false,
+ false, false, false, 0, false));
+ }
};
/// addDirectMem - This function is used to add a direct memory reference to the
if (AM.BaseType == X86AddressMode::RegBase)
MIB.addReg(AM.Base.Reg);
- else if (AM.BaseType == X86AddressMode::FrameIndexBase)
+ else {
+ assert(AM.BaseType == X86AddressMode::FrameIndexBase);
MIB.addFrameIndex(AM.Base.FrameIndex);
- else
- assert (0);
+ }
+
MIB.addImm(AM.Scale).addReg(AM.IndexReg);
if (AM.GV)
MIB.addGlobalAddress(AM.GV, AM.Disp, AM.GVOpFlags);
/// SetSSEDomain - Set the SSEDomain of MI.
void SetSSEDomain(MachineInstr *MI, unsigned Domain) const;
+ MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
+ MachineInstr* MI,
+ unsigned OpNum,
+ const SmallVectorImpl<MachineOperand> &MOs,
+ unsigned Size, unsigned Alignment) const;
+
private:
MachineInstr * convertToThreeAddressWithLEA(unsigned MIOpc,
MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI,
LiveVariables *LV) const;
- MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
- MachineInstr* MI,
- unsigned OpNum,
- const SmallVectorImpl<MachineOperand> &MOs,
- unsigned Size, unsigned Alignment) const;
-
/// isFrameOperand - Return true and the FrameIndex if the specified
/// operand and follow operands form a reference to the stack frame.
bool isFrameOperand(const MachineInstr *MI, unsigned int Op,
-; RUN: llc < %s -fast-isel -mtriple=i386-apple-darwin | \
-; RUN: grep lazy_ptr, | count 2
-; RUN: llc < %s -fast-isel -march=x86 -relocation-model=static | \
-; RUN: grep lea
+; RUN: llc < %s -fast-isel -mtriple=i386-apple-darwin | FileCheck %s
@src = external global i32
+; rdar://6653118
define i32 @loadgv() nounwind {
entry:
%0 = load i32* @src, align 4
%2 = add i32 %0, %1
store i32 %2, i32* @src
ret i32 %2
+; This should fold one of the loads into the add.
+; CHECK: loadgv:
+; CHECK: movl L_src$non_lazy_ptr, %ecx
+; CHECK: movl (%ecx), %eax
+; CHECK: addl (%ecx), %eax
+; CHECK: movl %eax, (%ecx)
+; CHECK: ret
+
}
%stuff = type { i32 (...)** }
entry:
store i32 (...)** getelementptr ([4 x i32 (...)*]* @LotsStuff, i32 0, i32 2), i32 (...)*** null, align 4
ret void
+; CHECK: _t:
+; CHECK: movl $0, %eax
+; CHECK: movl L_LotsStuff$non_lazy_ptr, %ecx
+
}
projects / oota-llvm.git / commitdiff