diff options
| -rw-r--r-- | lib/Target/X86/X86FastISel.cpp | 16 | ||||
| -rw-r--r-- | lib/Target/X86/X86FloatingPoint.cpp | 485 | ||||
| -rw-r--r-- | lib/Target/X86/X86ISelLowering.cpp | 11 | ||||
| -rw-r--r-- | lib/Target/X86/X86InstrFPStack.td | 40 | ||||
| -rw-r--r-- | lib/Target/X86/X86RegisterInfo.cpp | 12 | ||||
| -rw-r--r-- | lib/Target/X86/X86RegisterInfo.td | 25 | ||||
| -rw-r--r-- | test/CodeGen/X86/inline-asm-fpstack.ll | 169 |
7 files changed, 531 insertions, 227 deletions
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp index 82f5d3a..a4d1c67 100644 --- a/lib/Target/X86/X86FastISel.cpp +++ b/lib/Target/X86/X86FastISel.cpp @@ -1848,16 +1848,18 @@ bool X86FastISel::DoSelectCall(const Instruction *I, const char *MemIntName) { // stack, but where we prefer to use the value in xmm registers, copy it // out as F80 and use a truncate to move it from fp stack reg to xmm reg. if ((RVLocs[i].getLocReg() == X86::ST0 || - RVLocs[i].getLocReg() == X86::ST1) && - isScalarFPTypeInSSEReg(RVLocs[0].getValVT())) { - CopyVT = MVT::f80; + RVLocs[i].getLocReg() == X86::ST1)) { + if (isScalarFPTypeInSSEReg(RVLocs[i].getValVT())) + CopyVT = MVT::f80; CopyReg = createResultReg(X86::RFP80RegisterClass); + BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(X86::FpPOP_RETVAL), + CopyReg); + } else { + BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), + CopyReg).addReg(RVLocs[i].getLocReg()); + UsedRegs.push_back(RVLocs[i].getLocReg()); } - BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), - CopyReg).addReg(RVLocs[i].getLocReg()); - UsedRegs.push_back(RVLocs[i].getLocReg()); - if (CopyVT != RVLocs[i].getValVT()) { // Round the F80 the right size, which also moves to the appropriate xmm // register. This is accomplished by storing the F80 value in memory and diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp index e16f217..3fb5493 100644 --- a/lib/Target/X86/X86FloatingPoint.cpp +++ b/lib/Target/X86/X86FloatingPoint.cpp @@ -37,6 +37,7 @@ #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/Passes.h" +#include "llvm/InlineAsm.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" @@ -134,11 +135,36 @@ namespace { unsigned Stack[8]; // FP<n> Registers in each stack slot... unsigned StackTop; // The current top of the FP stack. + enum { + NumFPRegs = 16 // Including scratch pseudo-registers. + }; + // For each live FP<n> register, point to its Stack[] entry. // The first entries correspond to FP0-FP6, the rest are scratch registers // used when we need slightly different live registers than what the // register allocator thinks. - unsigned RegMap[16]; + unsigned RegMap[NumFPRegs]; + + // Pending fixed registers - Inline assembly needs FP registers to appear + // in fixed stack slot positions. This is handled by copying FP registers + // to ST registers before the instruction, and copying back after the + // instruction. + // + // This is modeled with pending ST registers. NumPendingSTs is the number + // of ST registers (ST0-STn) we are tracking. PendingST[n] points to an FP + // register that holds the ST value. The ST registers are not moved into + // place until immediately before the instruction that needs them. + // + // It can happen that we need an ST register to be live when no FP register + // holds the value: + // + // %ST0 = COPY %FP4<kill> + // + // When that happens, we allocate a scratch FP register to hold the ST + // value. That means every register in PendingST must be live. + + unsigned NumPendingSTs; + unsigned char PendingST[8]; // Set up our stack model to match the incoming registers to MBB. void setupBlockStack(); @@ -152,13 +178,15 @@ namespace { dbgs() << " FP" << Stack[i]; assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!"); } + for (unsigned i = 0; i != NumPendingSTs; ++i) + dbgs() << ", ST" << i << " in FP" << unsigned(PendingST[i]); dbgs() << "\n"; } /// getSlot - Return the stack slot number a particular register number is /// in. unsigned getSlot(unsigned RegNo) const { - assert(RegNo < array_lengthof(RegMap) && "Regno out of range!"); + assert(RegNo < NumFPRegs && "Regno out of range!"); return RegMap[RegNo]; } @@ -170,12 +198,17 @@ namespace { /// getScratchReg - Return an FP register that is not currently in use. unsigned getScratchReg() { - for (int i = array_lengthof(RegMap) - 1; i >= 8; --i) + for (int i = NumFPRegs - 1; i >= 8; --i) if (!isLive(i)) return i; llvm_unreachable("Ran out of scratch FP registers"); } + /// isScratchReg - Returns trus if RegNo is a scratch FP register. + bool isScratchReg(unsigned RegNo) { + return RegNo > 8 && RegNo < NumFPRegs; + } + /// getStackEntry - Return the X86::FP<n> register in register ST(i). unsigned getStackEntry(unsigned STi) const { if (STi >= StackTop) @@ -191,7 +224,7 @@ namespace { // pushReg - Push the specified FP<n> register onto the stack. void pushReg(unsigned Reg) { - assert(Reg < array_lengthof(RegMap) && "Register number out of range!"); + assert(Reg < NumFPRegs && "Register number out of range!"); if (StackTop >= 8) report_fatal_error("Stack overflow!"); Stack[StackTop] = Reg; @@ -261,7 +294,14 @@ namespace { void handleCondMovFP(MachineBasicBlock::iterator &I); void handleSpecialFP(MachineBasicBlock::iterator &I); - bool translateCopy(MachineInstr*); + // Check if a COPY instruction is using FP registers. + bool isFPCopy(MachineInstr *MI) { + unsigned DstReg = MI->getOperand(0).getReg(); + unsigned SrcReg = MI->getOperand(1).getReg(); + + return X86::RFP80RegClass.contains(DstReg) || + X86::RFP80RegClass.contains(SrcReg); + } }; char FPS::ID = 0; } @@ -351,6 +391,7 @@ void FPS::bundleCFG(MachineFunction &MF) { bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) { bool Changed = false; MBB = &BB; + NumPendingSTs = 0; setupBlockStack(); @@ -362,7 +403,7 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) { if (MI->isInlineAsm()) FPInstClass = X86II::SpecialFP; - if (MI->isCopy() && translateCopy(MI)) + if (MI->isCopy() && isFPCopy(MI)) FPInstClass = X86II::SpecialFP; if (FPInstClass == X86II::NotFP) @@ -891,7 +932,8 @@ void FPS::shuffleStackTop(const unsigned char *FixStack, continue; // (Reg st0) (OldReg st0) = (Reg OldReg st0) moveToTop(Reg, I); - moveToTop(OldReg, I); + if (FixCount > 0) + moveToTop(OldReg, I); } DEBUG(dumpStack()); } @@ -1249,142 +1291,309 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) { MachineInstr *MI = I; switch (MI->getOpcode()) { default: llvm_unreachable("Unknown SpecialFP instruction!"); - case X86::FpGET_ST0_32:// Appears immediately after a call returning FP type! - case X86::FpGET_ST0_64:// Appears immediately after a call returning FP type! - case X86::FpGET_ST0_80:// Appears immediately after a call returning FP type! - assert(StackTop == 0 && "Stack should be empty after a call!"); - pushReg(getFPReg(MI->getOperand(0))); - break; - case X86::FpGET_ST1_32:// Appears immediately after a call returning FP type! - case X86::FpGET_ST1_64:// Appears immediately after a call returning FP type! - case X86::FpGET_ST1_80:{// Appears immediately after a call returning FP type! - // FpGET_ST1 should occur right after a FpGET_ST0 for a call or inline asm. - // The pattern we expect is: - // CALL - // FP1 = FpGET_ST0 - // FP4 = FpGET_ST1 - // - // At this point, we've pushed FP1 on the top of stack, so it should be - // present if it isn't dead. If it was dead, we already emitted a pop to - // remove it from the stack and StackTop = 0. - - // Push FP4 as top of stack next. - pushReg(getFPReg(MI->getOperand(0))); + case TargetOpcode::COPY: { + // We handle three kinds of copies: FP <- FP, FP <- ST, and ST <- FP. + const MachineOperand &MO1 = MI->getOperand(1); + const MachineOperand &MO0 = MI->getOperand(0); + unsigned DstST = MO0.getReg() - X86::ST0; + unsigned SrcST = MO1.getReg() - X86::ST0; + bool KillsSrc = MI->killsRegister(MO1.getReg()); + + // ST = COPY FP. Set up a pending ST register. + if (DstST < 8) { + unsigned SrcFP = getFPReg(MO1); + assert(isLive(SrcFP) && "Cannot copy dead register"); + assert(!MO0.isDead() && "Cannot copy to dead ST register"); + + // Unallocated STs are marked as the nonexistent FP255. + while (NumPendingSTs <= DstST) + PendingST[NumPendingSTs++] = NumFPRegs; + + // STi could still be live from a previous inline asm. + if (isScratchReg(PendingST[DstST])) { + DEBUG(dbgs() << "Clobbering old ST in FP" << unsigned(PendingST[DstST]) + << '\n'); + freeStackSlotBefore(MI, PendingST[DstST]); + } - // If StackTop was 0 before we pushed our operand, then ST(0) must have been - // dead. In this case, the ST(1) value is the only thing that is live, so - // it should be on the TOS (after the pop that was emitted) and is. Just - // continue in this case. - if (StackTop == 1) + // When the source is killed, allocate a scratch FP register. + if (KillsSrc) { + unsigned Slot = getSlot(SrcFP); + unsigned SR = getScratchReg(); + PendingST[DstST] = SR; + Stack[Slot] = SR; + RegMap[SR] = Slot; + } else + PendingST[DstST] = SrcFP; break; - - // Because pushReg just pushed ST(1) as TOS, we now have to swap the two top - // elements so that our accounting is correct. - unsigned RegOnTop = getStackEntry(0); - unsigned RegNo = getStackEntry(1); - - // Swap the slots the regs are in. - std::swap(RegMap[RegNo], RegMap[RegOnTop]); - - // Swap stack slot contents. - if (RegMap[RegOnTop] >= StackTop) - report_fatal_error("Access past stack top!"); - std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]); - break; - } - case X86::FpSET_ST0_32: - case X86::FpSET_ST0_64: - case X86::FpSET_ST0_80: { - // FpSET_ST0_80 is generated by copyRegToReg for setting up inline asm - // arguments that use an st constraint. We expect a sequence of - // instructions: Fp_SET_ST0 Fp_SET_ST1? INLINEASM - unsigned Op0 = getFPReg(MI->getOperand(0)); - - if (!MI->killsRegister(X86::FP0 + Op0)) { - // Duplicate Op0 into a temporary on the stack top. - duplicateToTop(Op0, getScratchReg(), I); - } else { - // Op0 is killed, so just swap it into position. - moveToTop(Op0, I); } - --StackTop; // "Forget" we have something on the top of stack! - break; - } - case X86::FpSET_ST1_32: - case X86::FpSET_ST1_64: - case X86::FpSET_ST1_80: { - // Set up st(1) for inline asm. We are assuming that st(0) has already been - // set up by FpSET_ST0, and our StackTop is off by one because of it. - unsigned Op0 = getFPReg(MI->getOperand(0)); - // Restore the actual StackTop from before Fp_SET_ST0. - // Note we can't handle Fp_SET_ST1 without a preceding Fp_SET_ST0, and we - // are not enforcing the constraint. - ++StackTop; - unsigned RegOnTop = getStackEntry(0); // This reg must remain in st(0). - if (!MI->killsRegister(X86::FP0 + Op0)) { - duplicateToTop(Op0, getScratchReg(), I); - moveToTop(RegOnTop, I); - } else if (getSTReg(Op0) != X86::ST1) { - // We have the wrong value at st(1). Shuffle! Untested! - moveToTop(getStackEntry(1), I); - moveToTop(Op0, I); - moveToTop(RegOnTop, I); + + // FP = COPY ST. Extract fixed stack value. + // Any instruction defining ST registers must have assigned them to a + // scratch register. + if (SrcST < 8) { + unsigned DstFP = getFPReg(MO0); + assert(!isLive(DstFP) && "Cannot copy ST to live FP register"); + assert(NumPendingSTs > SrcST && "Cannot copy from dead ST register"); + unsigned SrcFP = PendingST[SrcST]; + assert(isScratchReg(SrcFP) && "Expected ST in a scratch register"); + assert(isLive(SrcFP) && "Scratch holding ST is dead"); + + // DstFP steals the stack slot from SrcFP. + unsigned Slot = getSlot(SrcFP); + Stack[Slot] = DstFP; + RegMap[DstFP] = Slot; + + // Always treat the ST as killed. + PendingST[SrcST] = NumFPRegs; + while (NumPendingSTs && PendingST[NumPendingSTs - 1] == NumFPRegs) + --NumPendingSTs; + break; } - assert(StackTop >= 2 && "Too few live registers"); - StackTop -= 2; // "Forget" both st(0) and st(1). - break; - } - case X86::MOV_Fp3232: - case X86::MOV_Fp3264: - case X86::MOV_Fp6432: - case X86::MOV_Fp6464: - case X86::MOV_Fp3280: - case X86::MOV_Fp6480: - case X86::MOV_Fp8032: - case X86::MOV_Fp8064: - case X86::MOV_Fp8080: { - const MachineOperand &MO1 = MI->getOperand(1); - unsigned SrcReg = getFPReg(MO1); - const MachineOperand &MO0 = MI->getOperand(0); - unsigned DestReg = getFPReg(MO0); - if (MI->killsRegister(X86::FP0+SrcReg)) { + // FP <- FP copy. + unsigned DstFP = getFPReg(MO0); + unsigned SrcFP = getFPReg(MO1); + assert(isLive(SrcFP) && "Cannot copy dead register"); + if (KillsSrc) { // If the input operand is killed, we can just change the owner of the // incoming stack slot into the result. - unsigned Slot = getSlot(SrcReg); - assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!"); - Stack[Slot] = DestReg; - RegMap[DestReg] = Slot; - + unsigned Slot = getSlot(SrcFP); + Stack[Slot] = DstFP; + RegMap[DstFP] = Slot; } else { - // For FMOV we just duplicate the specified value to a new stack slot. + // For COPY we just duplicate the specified value to a new stack slot. // This could be made better, but would require substantial changes. - duplicateToTop(SrcReg, DestReg, I); + duplicateToTop(SrcFP, DstFP, I); } + break; + } + + case X86::FpPOP_RETVAL: { + // The FpPOP_RETVAL instruction is used after calls that return a value on + // the floating point stack. We cannot model this with ST defs since CALL + // instructions have fixed clobber lists. This instruction is interpreted + // to mean that there is one more live register on the stack than we + // thought. + // + // This means that StackTop does not match the hardware stack between a + // call and the FpPOP_RETVAL instructions. We do tolerate FP instructions + // between CALL and FpPOP_RETVAL as long as they don't overflow the + // hardware stack. + unsigned DstFP = getFPReg(MI->getOperand(0)); + + // Move existing stack elements up to reflect reality. + assert(StackTop < 8 && "Stack overflowed before FpPOP_RETVAL"); + if (StackTop) { + std::copy_backward(Stack, Stack + StackTop, Stack + StackTop + 1); + for (unsigned i = 0; i != NumFPRegs; ++i) + ++RegMap[i]; } + ++StackTop; + + // DstFP is the new bottom of the stack. + Stack[0] = DstFP; + RegMap[DstFP] = 0; + + // DstFP will be killed by processBasicBlock if this was a dead def. break; + } + case TargetOpcode::INLINEASM: { // The inline asm MachineInstr currently only *uses* FP registers for the // 'f' constraint. These should be turned into the current ST(x) register - // in the machine instr. Also, any kills should be explicitly popped after - // the inline asm. - unsigned Kills = 0; + // in the machine instr. + // + // There are special rules for x87 inline assembly. The compiler must know + // exactly how many registers are popped and pushed implicitly by the asm. + // Otherwise it is not possible to restore the stack state after the inline + // asm. + // + // There are 3 kinds of input operands: + // + // 1. Popped inputs. These must appear at the stack top in ST0-STn. A + // popped input operand must be in a fixed stack slot, and it is either + // tied to an output operand, or in the clobber list. The MI has ST use + // and def operands for these inputs. + // + // 2. Fixed inputs. These inputs appear in fixed stack slots, but are + // preserved by the inline asm. The fixed stack slots must be STn-STm + // following the popped inputs. A fixed input operand cannot be tied to + // an output or appear in the clobber list. The MI has ST use operands + // and no defs for these inputs. + // + // 3. Preserved inputs. These inputs use the "f" constraint which is + // represented as an FP register. The inline asm won't change these + // stack slots. + // + // Outputs must be in ST registers, FP outputs are not allowed. Clobbered + // registers do not count as output operands. The inline asm changes the + // stack as if it popped all the popped inputs and then pushed all the + // output operands. + + // Scan the assembly for ST registers used, defined and clobbered. We can + // only tell clobbers from defs by looking at the asm descriptor. + unsigned STUses = 0, STDefs = 0, STClobbers = 0, STDeadDefs = 0; + unsigned NumOps = 0; + for (unsigned i = InlineAsm::MIOp_FirstOperand, e = MI->getNumOperands(); + i != e && MI->getOperand(i).isImm(); i += 1 + NumOps) { + unsigned Flags = MI->getOperand(i).getImm(); + NumOps = InlineAsm::getNumOperandRegisters(Flags); + if (NumOps != 1) + continue; + const MachineOperand &MO = MI->getOperand(i + 1); + if (!MO.isReg()) + continue; + unsigned STReg = MO.getReg() - X86::ST0; + if (STReg >= 8) + continue; + + switch (InlineAsm::getKind(Flags)) { + case InlineAsm::Kind_RegUse: + STUses |= (1u << STReg); + break; + case InlineAsm::Kind_RegDef: + case InlineAsm::Kind_RegDefEarlyClobber: + STDefs |= (1u << STReg); + if (MO.isDead()) + STDeadDefs |= (1u << STReg); + break; + case InlineAsm::Kind_Clobber: + STClobbers |= (1u << STReg); + break; + default: + break; + } + } + + if (STUses && !isMask_32(STUses)) + report_fatal_error("Inline asm fixed inputs" + " must be last on the x87 stack"); + unsigned NumSTUses = CountTrailingOnes_32(STUses); + + // Defs must be contiguous from the stack top. ST0-STn. + if (STDefs && !isMask_32(STDefs)) + report_fatal_error("Inline asm fixed outputs" + " must be last on the x87 stack"); + unsigned NumSTDefs = CountTrailingOnes_32(STDefs); + + // So must the clobbered stack slots. ST0-STm, m >= n. + if (STClobbers && !isMask_32(STDefs | STClobbers)) + report_fatal_error("Inline asm clobbers must be last on the x87 stack"); + + // Popped inputs are the ones that are also clobbered or defined. + unsigned STPopped = STUses & (STDefs | STClobbers); + if (STPopped && !isMask_32(STPopped)) + report_fatal_error("Inline asm popped inputs" + " must be last on the x87 stack"); + unsigned NumSTPopped = CountTrailingOnes_32(STPopped); + + DEBUG(dbgs() << "Asm uses " << NumSTUses << " fixed regs, pops " + << NumSTPopped << ", and defines " << NumSTDefs << " regs.\n"); + + // Scan the instruction for FP uses corresponding to "f" constraints. + // Collect FP registers to kill afer the instruction. + // Always kill all the scratch regs. + unsigned FPKills = ((1u << NumFPRegs) - 1) & ~0xff; + unsigned FPUsed = 0; for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { MachineOperand &Op = MI->getOperand(i); if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6) continue; - assert(Op.isUse() && "Only handle inline asm uses right now"); - + if (!Op.isUse()) + report_fatal_error("Illegal \"f\" output constraint in inline asm"); unsigned FPReg = getFPReg(Op); - Op.setReg(getSTReg(FPReg)); - + FPUsed |= 1U << FPReg; + // If we kill this operand, make sure to pop it from the stack after the // asm. We just remember it for now, and pop them all off at the end in // a batch. if (Op.isKill()) - Kills |= 1U << FPReg; + FPKills |= 1U << FPReg; + } + + // The popped inputs will be killed by the instruction, so duplicate them + // if the FP register needs to be live after the instruction, or if it is + // used in the instruction itself. We effectively treat the popped inputs + // as early clobbers. + for (unsigned i = 0; i < NumSTPopped; ++i) { + if ((FPKills & ~FPUsed) & (1u << PendingST[i])) + continue; + unsigned SR = getScratchReg(); + duplicateToTop(PendingST[i], SR, I); + DEBUG(dbgs() << "Duplicating ST" << i << " in FP" + << unsigned(PendingST[i]) << " to avoid clobbering it.\n"); + PendingST[i] = SR; + } + + // Make sure we have a unique live register for every fixed use. Some of + // them could be undef uses, and we need to emit LD_F0 instructions. + for (unsigned i = 0; i < NumSTUses; ++i) { + if (i < NumPendingSTs && PendingST[i] < NumFPRegs) { + // Check for shared assignments. + for (unsigned j = 0; j < i; ++j) { + if (PendingST[j] != PendingST[i]) + continue; + // STi and STj are inn the same register, create a copy. + unsigned SR = getScratchReg(); + duplicateToTop(PendingST[i], SR, I); + DEBUG(dbgs() << "Duplicating ST" << i << " in FP" + << unsigned(PendingST[i]) + << " to avoid collision with ST" << j << '\n'); + PendingST[i] = SR; + } + continue; + } + unsigned SR = getScratchReg(); + DEBUG(dbgs() << "Emitting LD_F0 for ST" << i << " in FP" << SR << '\n'); + BuildMI(*MBB, I, MI->getDebugLoc(), TII->get(X86::LD_F0)); + pushReg(SR); + PendingST[i] = SR; + if (NumPendingSTs == i) + ++NumPendingSTs; + } + assert(NumPendingSTs >= NumSTUses && "Fixed registers should be assigned"); + + // Now we can rearrange the live registers to match what was requested. + shuffleStackTop(PendingST, NumPendingSTs, I); + DEBUG({dbgs() << "Before asm: "; dumpStack();}); + + // With the stack layout fixed, rewrite the FP registers. + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { + MachineOperand &Op = MI->getOperand(i); + if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6) + continue; + unsigned FPReg = getFPReg(Op); + Op.setReg(getSTReg(FPReg)); } + // Simulate the inline asm popping its inputs and pushing its outputs. + StackTop -= NumSTPopped; + + // Hold the fixed output registers in scratch FP registers. They will be + // transferred to real FP registers by copies. + NumPendingSTs = 0; + for (unsigned i = 0; i < NumSTDefs; ++i) { + unsigned SR = getScratchReg(); + pushReg(SR); + FPKills &= ~(1u << SR); + } + for (unsigned i = 0; i < NumSTDefs; ++i) + PendingST[NumPendingSTs++] = getStackEntry(i); + DEBUG({dbgs() << "After asm: "; dumpStack();}); + + // If any of the ST defs were dead, pop them immediately. Our caller only + // handles dead FP defs. + MachineBasicBlock::iterator InsertPt = MI; + for (unsigned i = 0; STDefs & (1u << i); ++i) { + if (!(STDeadDefs & (1u << i))) + continue; + freeStackSlotAfter(InsertPt, PendingST[i]); + PendingST[i] = NumFPRegs; + } + while (NumPendingSTs && PendingST[NumPendingSTs - 1] == NumFPRegs) + --NumPendingSTs; + // If this asm kills any FP registers (is the last use of them) we must // explicitly emit pop instructions for them. Do this now after the asm has // executed so that the ST(x) numbers are not off (which would happen if we @@ -1392,16 +1601,16 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) { // // Note: this might be a non-optimal pop sequence. We might be able to do // better by trying to pop in stack order or something. - MachineBasicBlock::iterator InsertPt = MI; - while (Kills) { - unsigned FPReg = CountTrailingZeros_32(Kills); - freeStackSlotAfter(InsertPt, FPReg); - Kills &= ~(1U << FPReg); + while (FPKills) { + unsigned FPReg = CountTrailingZeros_32(FPKills); + if (isLive(FPReg)) + freeStackSlotAfter(InsertPt, FPReg); + FPKills &= ~(1U << FPReg); } // Don't delete the inline asm! return; } - + case X86::RET: case X86::RETI: // If RET has an FP register use operand, pass the first one in ST(0) and @@ -1499,33 +1708,3 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) { } else --I; } - -// Translate a COPY instruction to a pseudo-op that handleSpecialFP understands. -bool FPS::translateCopy(MachineInstr *MI) { - unsigned DstReg = MI->getOperand(0).getReg(); - unsigned SrcReg = MI->getOperand(1).getReg(); - - if (DstReg == X86::ST0) { - MI->setDesc(TII->get(X86::FpSET_ST0_80)); - MI->RemoveOperand(0); - return true; - } - if (DstReg == X86::ST1) { - MI->setDesc(TII->get(X86::FpSET_ST1_80)); - MI->RemoveOperand(0); - return true; - } - if (SrcReg == X86::ST0) { - MI->setDesc(TII->get(X86::FpGET_ST0_80)); - return true; - } - if (SrcReg == X86::ST1) { - MI->setDesc(TII->get(X86::FpGET_ST1_80)); - return true; - } - if (X86::RFP80RegClass.contains(DstReg, SrcReg)) { - MI->setDesc(TII->get(X86::MOV_Fp8080)); - return true; - } - return false; -} diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 0810267..b327f1b 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -1511,20 +1511,15 @@ X86TargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag, // If this is a call to a function that returns an fp value on the floating // point stack, we must guarantee the the value is popped from the stack, so // a CopyFromReg is not good enough - the copy instruction may be eliminated - // if the return value is not used. We use the FpGET_ST0 instructions + // if the return value is not used. We use the FpPOP_RETVAL instruction // instead. if (VA.getLocReg() == X86::ST0 || VA.getLocReg() == X86::ST1) { // If we prefer to use the value in xmm registers, copy it out as f80 and // use a truncate to move it from fp stack reg to xmm reg. if (isScalarFPTypeInSSEReg(VA.getValVT())) CopyVT = MVT::f80; - bool isST0 = VA.getLocReg() == X86::ST0; - unsigned Opc = 0; - if (CopyVT == MVT::f32) Opc = isST0 ? X86::FpGET_ST0_32:X86::FpGET_ST1_32; - if (CopyVT == MVT::f64) Opc = isST0 ? X86::FpGET_ST0_64:X86::FpGET_ST1_64; - if (CopyVT == MVT::f80) Opc = isST0 ? X86::FpGET_ST0_80:X86::FpGET_ST1_80; SDValue Ops[] = { Chain, InFlag }; - Chain = SDValue(DAG.getMachineNode(Opc, dl, CopyVT, MVT::Other, MVT::Glue, - Ops, 2), 1); + Chain = SDValue(DAG.getMachineNode(X86::FpPOP_RETVAL, dl, CopyVT, + MVT::Other, MVT::Glue, Ops, 2), 1); Val = Chain.getValue(0); // Round the f80 to the right size, which also moves it to the appropriate diff --git a/lib/Target/X86/X86InstrFPStack.td b/lib/Target/X86/X86InstrFPStack.td index b506f5e..7cb870f 100644 --- a/lib/Target/X86/X86InstrFPStack.td +++ b/lib/Target/X86/X86InstrFPStack.td @@ -112,31 +112,8 @@ let usesCustomInserter = 1 in { // Expanded after instruction selection. // a pattern) and the FPI instruction should have emission info (e.g. opcode // encoding and asm printing info). -// Pseudo Instructions for FP stack return values. -def FpGET_ST0_32 : FpI_<(outs RFP32:$dst), (ins), SpecialFP, []>; // FPR = ST(0) -def FpGET_ST0_64 : FpI_<(outs RFP64:$dst), (ins), SpecialFP, []>; // FPR = ST(0) -def FpGET_ST0_80 : FpI_<(outs RFP80:$dst), (ins), SpecialFP, []>; // FPR = ST(0) - -// FpGET_ST1* should only be issued *after* an FpGET_ST0* has been issued when -// there are two values live out on the stack from a call or inlineasm. This -// magic is handled by the stackifier. It is not valid to emit FpGET_ST1* and -// then FpGET_ST0*. In addition, it is invalid for any FP-using operations to -// occur between them. -def FpGET_ST1_32 : FpI_<(outs RFP32:$dst), (ins), SpecialFP, []>; // FPR = ST(1) -def FpGET_ST1_64 : FpI_<(outs RFP64:$dst), (ins), SpecialFP, []>; // FPR = ST(1) -def FpGET_ST1_80 : FpI_<(outs RFP80:$dst), (ins), SpecialFP, []>; // FPR = ST(1) - -let Defs = [ST0] in { -def FpSET_ST0_32 : FpI_<(outs), (ins RFP32:$src), SpecialFP, []>; // ST(0) = FPR -def FpSET_ST0_64 : FpI_<(outs), (ins RFP64:$src), SpecialFP, []>; // ST(0) = FPR -def FpSET_ST0_80 : FpI_<(outs), (ins RFP80:$src), SpecialFP, []>; // ST(0) = FPR -} - -let Defs = [ST1] in { -def FpSET_ST1_32 : FpI_<(outs), (ins RFP32:$src), SpecialFP, []>; // ST(1) = FPR -def FpSET_ST1_64 : FpI_<(outs), (ins RFP64:$src), SpecialFP, []>; // ST(1) = FPR -def FpSET_ST1_80 : FpI_<(outs), (ins RFP80:$src), SpecialFP, []>; // ST(1) = FPR -} +// Pseudo Instruction for FP stack return values. +def FpPOP_RETVAL : FpI_<(outs RFP80:$dst), (ins), SpecialFP, []>; // FpIf32, FpIf64 - Floating Point Pseudo Instruction template. // f32 instructions can use SSE1 and are predicated on FPStackf32 == !SSE1. @@ -147,19 +124,6 @@ class FpIf32<dag outs, dag ins, FPFormat fp, list<dag> pattern> : class FpIf64<dag outs, dag ins, FPFormat fp, list<dag> pattern> : FpI_<outs, ins, fp, pattern>, Requires<[FPStackf64]>; -// Register copies. Just copies, the shortening ones do not truncate. -let neverHasSideEffects = 1 in { - def MOV_Fp3232 : FpIf32<(outs RFP32:$dst), (ins RFP32:$src), SpecialFP, []>; - def MOV_Fp3264 : FpIf32<(outs RFP64:$dst), (ins RFP32:$src), SpecialFP, []>; - def MOV_Fp6432 : FpIf32<(outs RFP32:$dst), (ins RFP64:$src), SpecialFP, []>; - def MOV_Fp6464 : FpIf64<(outs RFP64:$dst), (ins RFP64:$src), SpecialFP, []>; - def MOV_Fp8032 : FpIf32<(outs RFP32:$dst), (ins RFP80:$src), SpecialFP, []>; - def MOV_Fp3280 : FpIf32<(outs RFP80:$dst), (ins RFP32:$src), SpecialFP, []>; - def MOV_Fp8064 : FpIf64<(outs RFP64:$dst), (ins RFP80:$src), SpecialFP, []>; - def MOV_Fp6480 : FpIf64<(outs RFP80:$dst), (ins RFP64:$src), SpecialFP, []>; - def MOV_Fp8080 : FpI_ <(outs RFP80:$dst), (ins RFP80:$src), SpecialFP, []>; -} - // Factoring for arithmetic. multiclass FPBinary_rr<SDNode OpNode> { // Register op register -> register diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index 48f60f8..9e4fdad 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -500,18 +500,6 @@ BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const { Reserved.set(X86::BPL); } - // Mark the x87 stack registers as reserved, since they don't behave normally - // with respect to liveness. We don't fully model the effects of x87 stack - // pushes and pops after stackification. - Reserved.set(X86::ST0); - Reserved.set(X86::ST1); - Reserved.set(X86::ST2); - Reserved.set(X86::ST3); - Reserved.set(X86::ST4); - Reserved.set(X86::ST5); - Reserved.set(X86::ST6); - Reserved.set(X86::ST7); - // Mark the segment registers as reserved. Reserved.set(X86::CS); Reserved.set(X86::SS); diff --git a/lib/Target/X86/X86RegisterInfo.td b/lib/Target/X86/X86RegisterInfo.td index 14d6d64..203722a 100644 --- a/lib/Target/X86/X86RegisterInfo.td +++ b/lib/Target/X86/X86RegisterInfo.td @@ -206,15 +206,22 @@ let Namespace = "X86" in { def YMM15: RegisterWithSubRegs<"ymm15", [XMM15]>, DwarfRegAlias<XMM15>; } - // Floating point stack registers - def ST0 : Register<"st(0)">, DwarfRegNum<[33, 12, 11]>; - def ST1 : Register<"st(1)">, DwarfRegNum<[34, 13, 12]>; - def ST2 : Register<"st(2)">, DwarfRegNum<[35, 14, 13]>; - def ST3 : Register<"st(3)">, DwarfRegNum<[36, 15, 14]>; - def ST4 : Register<"st(4)">, DwarfRegNum<[37, 16, 15]>; - def ST5 : Register<"st(5)">, DwarfRegNum<[38, 17, 16]>; - def ST6 : Register<"st(6)">, DwarfRegNum<[39, 18, 17]>; - def ST7 : Register<"st(7)">, DwarfRegNum<[40, 19, 18]>; + class STRegister<string Name, list<Register> A> : Register<Name> { + let Aliases = A; + } + + // Floating point stack registers. These don't map one-to-one to the FP + // pseudo registers, but we still mark them as aliasing FP registers. That + // way both kinds can be live without exceeding the stack depth. ST registers + // are only live around inline assembly. + def ST0 : STRegister<"st(0)", []>, DwarfRegNum<[33, 12, 11]>; + def ST1 : STRegister<"st(1)", [FP6]>, DwarfRegNum<[34, 13, 12]>; + def ST2 : STRegister<"st(2)", [FP5]>, DwarfRegNum<[35, 14, 13]>; + def ST3 : STRegister<"st(3)", [FP4]>, DwarfRegNum<[36, 15, 14]>; + def ST4 : STRegister<"st(4)", [FP3]>, DwarfRegNum<[37, 16, 15]>; + def ST5 : STRegister<"st(5)", [FP2]>, DwarfRegNum<[38, 17, 16]>; + def ST6 : STRegister<"st(6)", [FP1]>, DwarfRegNum<[39, 18, 17]>; + def ST7 : STRegister<"st(7)", [FP0]>, DwarfRegNum<[40, 19, 18]>; // Status flags register def EFLAGS : Register<"flags">; diff --git a/test/CodeGen/X86/inline-asm-fpstack.ll b/test/CodeGen/X86/inline-asm-fpstack.ll index d15f7ff..8e48bbe 100644 --- a/test/CodeGen/X86/inline-asm-fpstack.ll +++ b/test/CodeGen/X86/inline-asm-fpstack.ll @@ -106,6 +106,25 @@ return: ret void } +; Passing a non-killed value through asm in {st}. +; Make sure it is not duped before. +; Second asm kills st(0), so we shouldn't pop anything +; CHECK: testPR4185b +; CHECK-NOT: fld %st(0) +; CHECK: fistl +; CHECK-NOT: fstp +; CHECK: fistpl +; CHECK-NOT: fstp +; CHECK: ret +; A valid alternative would be to remat the constant pool load before each +; inline asm. +define void @testPR4185b() { +return: + call void asm sideeffect "fistl $0", "{st}"(double 1.000000e+06) + call void asm sideeffect "fistpl $0", "{st},~{st}"(double 1.000000e+06) + ret void +} + ; PR4459 ; The return value from ceil must be duped before being consumed by asm. ; CHECK: testPR4459 @@ -160,3 +179,153 @@ entry: tail call void asm sideeffect "fistpl $0", "{st},~{st}"(x86_fp80 %5) ret void } + +; An input argument in a fixed position is implicitly popped by the asm only if +; the input argument is tied to an output register, or it is in the clobber list. +; The clobber list case is tested above. +; +; This doesn't implicitly pop the stack: +; +; void fist1(long double x, int *p) { +; asm volatile ("fistl %1" : : "t"(x), "m"(*p)); +; } +; +; CHECK: fist1 +; CHECK: fldt +; CHECK: fistl (%e +; CHECK: fstp +; CHECK: ret +define void @fist1(x86_fp80 %x, i32* %p) nounwind ssp { +entry: + tail call void asm sideeffect "fistl $1", "{st},*m,~{memory},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, i32* %p) nounwind + ret void +} + +; Here, the input operand is tied to an output which means that is is +; implicitly popped (and then the output is implicitly pushed). +; +; long double fist2(long double x, int *p) { +; long double y; +; asm ("fistl %1" : "=&t"(y) : "0"(x), "m"(*p) : "memory"); +; return y; +; } +; +; CHECK: fist2 +; CHECK: fldt +; CHECK: fistl (%e +; CHECK-NOT: fstp +; CHECK: ret +define x86_fp80 @fist2(x86_fp80 %x, i32* %p) nounwind ssp { +entry: + %0 = tail call x86_fp80 asm "fistl $2", "=&{st},0,*m,~{memory},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, i32* %p) nounwind + ret x86_fp80 %0 +} + +; An 'f' constraint is never implicitly popped: +; +; void fucomp1(long double x, long double y) { +; asm volatile ("fucomp %1" : : "t"(x), "f"(y) : "st"); +; } +; CHECK: fucomp1 +; CHECK: fldt +; CHECK: fldt +; CHECK: fucomp %st +; CHECK: fstp +; CHECK-NOT: fstp +; CHECK: ret +define void @fucomp1(x86_fp80 %x, x86_fp80 %y) nounwind ssp { +entry: + tail call void asm sideeffect "fucomp $1", "{st},f,~{st},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind + ret void +} + +; The 'u' constraint is only popped implicitly when clobbered: +; +; void fucomp2(long double x, long double y) { +; asm volatile ("fucomp %1" : : "t"(x), "u"(y) : "st"); +; } +; +; void fucomp3(long double x, long double y) { +; asm volatile ("fucompp %1" : : "t"(x), "u"(y) : "st", "st(1)"); +; } +; +; CHECK: fucomp2 +; CHECK: fldt +; CHECK: fldt +; CHECK: fucomp %st(1) +; CHECK: fstp +; CHECK-NOT: fstp +; CHECK: ret +; +; CHECK: fucomp3 +; CHECK: fldt +; CHECK: fldt +; CHECK: fucompp %st(1) +; CHECK-NOT: fstp +; CHECK: ret +define void @fucomp2(x86_fp80 %x, x86_fp80 %y) nounwind ssp { +entry: + tail call void asm sideeffect "fucomp $1", "{st},{st(1)},~{st},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind + ret void +} +define void @fucomp3(x86_fp80 %x, x86_fp80 %y) nounwind ssp { +entry: + tail call void asm sideeffect "fucompp $1", "{st},{st(1)},~{st},~{st(1)},~{dirflag},~{fpsr},~{flags}"(x86_fp80 %x, x86_fp80 %y) nounwind + ret void +} + +; One input, two outputs, one dead output. +%complex = type { float, float } +; CHECK: sincos1 +; CHECK: flds +; CHECK-NOT: fxch +; CHECK: sincos +; CHECK-NOT: fstp +; CHECK: fstp %st(1) +; CHECK-NOT: fstp +; CHECK: ret +define float @sincos1(float %x) nounwind ssp { +entry: + %0 = tail call %complex asm "sincos", "={st},={st(1)},0,~{dirflag},~{fpsr},~{flags}"(float %x) nounwind + %asmresult = extractvalue %complex %0, 0 + ret float %asmresult +} + +; Same thing, swapped output operands. +; CHECK: sincos2 +; CHECK: flds +; CHECK-NOT: fxch +; CHECK: sincos +; CHECK-NOT: fstp +; CHECK: fstp %st(1) +; CHECK-NOT: fstp +; CHECK: ret +define float @sincos2(float %x) nounwind ssp { +entry: + %0 = tail call %complex asm "sincos", "={st(1)},={st},1,~{dirflag},~{fpsr},~{flags}"(float %x) nounwind + %asmresult = extractvalue %complex %0, 1 + ret float %asmresult +} + +; Clobber st(0) after it was live-out/dead from the previous asm. +; CHECK: sincos3 +; Load x, make a copy for the second asm. +; CHECK: flds +; CHECK: fld %st(0) +; CHECK: sincos +; Discard dead result in st(0), bring x to the top. +; CHECK: fstp %st(0) +; CHECK: fxch +; x is now in st(0) for the second asm +; CHECK: sincos +; Discard both results. +; CHECK: fstp +; CHECK: fstp +; CHECK: ret +define float @sincos3(float %x) nounwind ssp { +entry: + %0 = tail call %complex asm sideeffect "sincos", "={st(1)},={st},1,~{dirflag},~{fpsr},~{flags}"(float %x) nounwind + %1 = tail call %complex asm sideeffect "sincos", "={st(1)},={st},1,~{dirflag},~{fpsr},~{flags}"(float %x) nounwind + %asmresult = extractvalue %complex %0, 0 + ret float %asmresult +} |