Add support for rematerializing FsFLD0SS and FsFLD0SD as constant-pool
loads in order to reduce register pressure. llvm-svn: 82470
This commit is contained in:
Dan Gohman
parent
d328d57c39
commit
69499b13fd
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@ -2297,9 +2297,21 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
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unsigned Alignment = 0;
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if (LoadMI->hasOneMemOperand())
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Alignment = LoadMI->memoperands_begin()->getAlignment();
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else if (LoadMI->getOpcode() == X86::V_SET0 ||
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LoadMI->getOpcode() == X86::V_SETALLONES)
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Alignment = 16;
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else
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switch (LoadMI->getOpcode()) {
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case X86::V_SET0:
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case X86::V_SETALLONES:
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Alignment = 16;
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break;
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case X86::FsFLD0SD:
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Alignment = 8;
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break;
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case X86::FsFLD0SS:
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Alignment = 4;
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break;
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default:
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llvm_unreachable("Don't know how to fold this instruction!");
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}
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if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
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unsigned NewOpc = 0;
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switch (MI->getOpcode()) {
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@ -2316,8 +2328,11 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
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return NULL;
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SmallVector<MachineOperand,X86AddrNumOperands> MOs;
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if (LoadMI->getOpcode() == X86::V_SET0 ||
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LoadMI->getOpcode() == X86::V_SETALLONES) {
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switch (LoadMI->getOpcode()) {
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case X86::V_SET0:
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case X86::V_SETALLONES:
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case X86::FsFLD0SD:
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case X86::FsFLD0SS: {
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// Folding a V_SET0 or V_SETALLONES as a load, to ease register pressure.
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// Create a constant-pool entry and operands to load from it.
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@ -2331,17 +2346,22 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
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// This doesn't work for several reasons.
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// 1. GlobalBaseReg may have been spilled.
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// 2. It may not be live at MI.
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return false;
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return NULL;
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}
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// Create a v4i32 constant-pool entry.
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// Create a constant-pool entry.
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MachineConstantPool &MCP = *MF.getConstantPool();
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const VectorType *Ty =
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VectorType::get(Type::getInt32Ty(MF.getFunction()->getContext()), 4);
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Constant *C = LoadMI->getOpcode() == X86::V_SET0 ?
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Constant::getNullValue(Ty) :
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Constant::getAllOnesValue(Ty);
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unsigned CPI = MCP.getConstantPoolIndex(C, 16);
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const Type *Ty;
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if (LoadMI->getOpcode() == X86::FsFLD0SS)
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Ty = Type::getFloatTy(MF.getFunction()->getContext());
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else if (LoadMI->getOpcode() == X86::FsFLD0SD)
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Ty = Type::getDoubleTy(MF.getFunction()->getContext());
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else
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Ty = VectorType::get(Type::getInt32Ty(MF.getFunction()->getContext()), 4);
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Constant *C = LoadMI->getOpcode() == X86::V_SETALLONES ?
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Constant::getAllOnesValue(Ty) :
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Constant::getNullValue(Ty);
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unsigned CPI = MCP.getConstantPoolIndex(C, Alignment);
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// Create operands to load from the constant pool entry.
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MOs.push_back(MachineOperand::CreateReg(PICBase, false));
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@ -2349,11 +2369,15 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
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MOs.push_back(MachineOperand::CreateReg(0, false));
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MOs.push_back(MachineOperand::CreateCPI(CPI, 0));
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MOs.push_back(MachineOperand::CreateReg(0, false));
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} else {
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break;
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}
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default: {
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// Folding a normal load. Just copy the load's address operands.
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unsigned NumOps = LoadMI->getDesc().getNumOperands();
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for (unsigned i = NumOps - X86AddrNumOperands; i != NumOps; ++i)
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MOs.push_back(LoadMI->getOperand(i));
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break;
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}
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}
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return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, 0, Alignment);
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}
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@ -472,7 +472,8 @@ def Int_COMISSrm: PSI<0x2F, MRMSrcMem, (outs), (ins VR128:$src1, f128mem:$src2),
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// that start with 'Fs'.
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// Alias instructions that map fld0 to pxor for sse.
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let isReMaterializable = 1, isAsCheapAsAMove = 1, isCodeGenOnly = 1 in
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let isReMaterializable = 1, isAsCheapAsAMove = 1, isCodeGenOnly = 1,
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canFoldAsLoad = 1 in
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def FsFLD0SS : I<0xEF, MRMInitReg, (outs FR32:$dst), (ins),
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"pxor\t$dst, $dst", [(set FR32:$dst, fp32imm0)]>,
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Requires<[HasSSE1]>, TB, OpSize;
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@ -1230,7 +1231,8 @@ def Int_COMISDrm: PDI<0x2F, MRMSrcMem, (outs), (ins VR128:$src1, f128mem:$src2),
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// that start with 'Fs'.
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// Alias instructions that map fld0 to pxor for sse.
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let isReMaterializable = 1, isAsCheapAsAMove = 1, isCodeGenOnly = 1 in
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let isReMaterializable = 1, isAsCheapAsAMove = 1, isCodeGenOnly = 1,
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canFoldAsLoad = 1 in
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def FsFLD0SD : I<0xEF, MRMInitReg, (outs FR64:$dst), (ins),
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"pxor\t$dst, $dst", [(set FR64:$dst, fpimm0)]>,
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Requires<[HasSSE2]>, TB, OpSize;
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@ -0,0 +1,95 @@
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; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu > %t
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; RUN: not grep xor %t
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; RUN: not grep movap %t
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; RUN: grep {\\.zero} %t
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; Remat should be able to fold the zero constant into the div instructions
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; as a constant-pool load.
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define void @foo(double* nocapture %x, double* nocapture %y) nounwind {
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entry:
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%tmp1 = load double* %x ; <double> [#uses=1]
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%arrayidx4 = getelementptr inbounds double* %x, i64 1 ; <double*> [#uses=1]
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%tmp5 = load double* %arrayidx4 ; <double> [#uses=1]
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%arrayidx8 = getelementptr inbounds double* %x, i64 2 ; <double*> [#uses=1]
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%tmp9 = load double* %arrayidx8 ; <double> [#uses=1]
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%arrayidx12 = getelementptr inbounds double* %x, i64 3 ; <double*> [#uses=1]
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%tmp13 = load double* %arrayidx12 ; <double> [#uses=1]
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%arrayidx16 = getelementptr inbounds double* %x, i64 4 ; <double*> [#uses=1]
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%tmp17 = load double* %arrayidx16 ; <double> [#uses=1]
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%arrayidx20 = getelementptr inbounds double* %x, i64 5 ; <double*> [#uses=1]
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%tmp21 = load double* %arrayidx20 ; <double> [#uses=1]
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%arrayidx24 = getelementptr inbounds double* %x, i64 6 ; <double*> [#uses=1]
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%tmp25 = load double* %arrayidx24 ; <double> [#uses=1]
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%arrayidx28 = getelementptr inbounds double* %x, i64 7 ; <double*> [#uses=1]
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%tmp29 = load double* %arrayidx28 ; <double> [#uses=1]
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%arrayidx32 = getelementptr inbounds double* %x, i64 8 ; <double*> [#uses=1]
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%tmp33 = load double* %arrayidx32 ; <double> [#uses=1]
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%arrayidx36 = getelementptr inbounds double* %x, i64 9 ; <double*> [#uses=1]
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%tmp37 = load double* %arrayidx36 ; <double> [#uses=1]
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%arrayidx40 = getelementptr inbounds double* %x, i64 10 ; <double*> [#uses=1]
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%tmp41 = load double* %arrayidx40 ; <double> [#uses=1]
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%arrayidx44 = getelementptr inbounds double* %x, i64 11 ; <double*> [#uses=1]
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%tmp45 = load double* %arrayidx44 ; <double> [#uses=1]
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%arrayidx48 = getelementptr inbounds double* %x, i64 12 ; <double*> [#uses=1]
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%tmp49 = load double* %arrayidx48 ; <double> [#uses=1]
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%arrayidx52 = getelementptr inbounds double* %x, i64 13 ; <double*> [#uses=1]
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%tmp53 = load double* %arrayidx52 ; <double> [#uses=1]
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%arrayidx56 = getelementptr inbounds double* %x, i64 14 ; <double*> [#uses=1]
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%tmp57 = load double* %arrayidx56 ; <double> [#uses=1]
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%arrayidx60 = getelementptr inbounds double* %x, i64 15 ; <double*> [#uses=1]
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%tmp61 = load double* %arrayidx60 ; <double> [#uses=1]
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%arrayidx64 = getelementptr inbounds double* %x, i64 16 ; <double*> [#uses=1]
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%tmp65 = load double* %arrayidx64 ; <double> [#uses=1]
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%div = fdiv double %tmp1, 0.000000e+00 ; <double> [#uses=1]
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store double %div, double* %y
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%div70 = fdiv double %tmp5, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx72 = getelementptr inbounds double* %y, i64 1 ; <double*> [#uses=1]
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store double %div70, double* %arrayidx72
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%div74 = fdiv double %tmp9, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx76 = getelementptr inbounds double* %y, i64 2 ; <double*> [#uses=1]
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store double %div74, double* %arrayidx76
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%div78 = fdiv double %tmp13, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx80 = getelementptr inbounds double* %y, i64 3 ; <double*> [#uses=1]
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store double %div78, double* %arrayidx80
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%div82 = fdiv double %tmp17, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx84 = getelementptr inbounds double* %y, i64 4 ; <double*> [#uses=1]
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store double %div82, double* %arrayidx84
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%div86 = fdiv double %tmp21, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx88 = getelementptr inbounds double* %y, i64 5 ; <double*> [#uses=1]
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store double %div86, double* %arrayidx88
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%div90 = fdiv double %tmp25, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx92 = getelementptr inbounds double* %y, i64 6 ; <double*> [#uses=1]
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store double %div90, double* %arrayidx92
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%div94 = fdiv double %tmp29, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx96 = getelementptr inbounds double* %y, i64 7 ; <double*> [#uses=1]
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store double %div94, double* %arrayidx96
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%div98 = fdiv double %tmp33, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx100 = getelementptr inbounds double* %y, i64 8 ; <double*> [#uses=1]
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store double %div98, double* %arrayidx100
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%div102 = fdiv double %tmp37, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx104 = getelementptr inbounds double* %y, i64 9 ; <double*> [#uses=1]
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store double %div102, double* %arrayidx104
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%div106 = fdiv double %tmp41, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx108 = getelementptr inbounds double* %y, i64 10 ; <double*> [#uses=1]
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store double %div106, double* %arrayidx108
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%div110 = fdiv double %tmp45, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx112 = getelementptr inbounds double* %y, i64 11 ; <double*> [#uses=1]
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store double %div110, double* %arrayidx112
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%div114 = fdiv double %tmp49, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx116 = getelementptr inbounds double* %y, i64 12 ; <double*> [#uses=1]
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store double %div114, double* %arrayidx116
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%div118 = fdiv double %tmp53, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx120 = getelementptr inbounds double* %y, i64 13 ; <double*> [#uses=1]
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store double %div118, double* %arrayidx120
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%div122 = fdiv double %tmp57, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx124 = getelementptr inbounds double* %y, i64 14 ; <double*> [#uses=1]
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store double %div122, double* %arrayidx124
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%div126 = fdiv double %tmp61, 2.000000e-01 ; <double> [#uses=1]
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%arrayidx128 = getelementptr inbounds double* %y, i64 15 ; <double*> [#uses=1]
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store double %div126, double* %arrayidx128
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%div130 = fdiv double %tmp65, 0.000000e+00 ; <double> [#uses=1]
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%arrayidx132 = getelementptr inbounds double* %y, i64 16 ; <double*> [#uses=1]
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store double %div130, double* %arrayidx132
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ret void
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}
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