diff options
Diffstat (limited to 'llvm/lib/Target/X86')
| -rw-r--r-- | llvm/lib/Target/X86/X86.td | 6 | ||||
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 68 | ||||
| -rw-r--r-- | llvm/lib/Target/X86/X86Subtarget.cpp | 2 | ||||
| -rw-r--r-- | llvm/lib/Target/X86/X86Subtarget.h | 12 | ||||
| -rw-r--r-- | llvm/lib/Target/X86/X86TargetMachine.cpp | 7 |
5 files changed, 41 insertions, 54 deletions
diff --git a/llvm/lib/Target/X86/X86.td b/llvm/lib/Target/X86/X86.td index c70e2e95463..7001910a61e 100644 --- a/llvm/lib/Target/X86/X86.td +++ b/llvm/lib/Target/X86/X86.td @@ -188,10 +188,6 @@ def FeatureSlowLEA : SubtargetFeature<"slow-lea", "SlowLEA", "true", "LEA instruction with certain arguments is slow">; def FeatureSlowIncDec : SubtargetFeature<"slow-incdec", "SlowIncDec", "true", "INC and DEC instructions are slower than ADD and SUB">; -def FeatureUseSqrtEst : SubtargetFeature<"use-sqrt-est", "UseSqrtEst", "true", - "Use RSQRT* to optimize square root calculations">; -def FeatureUseRecipEst : SubtargetFeature<"use-recip-est", "UseReciprocalEst", - "true", "Use RCP* to optimize division calculations">; def FeatureSoftFloat : SubtargetFeature<"soft-float", "UseSoftFloat", "true", "Use software floating point features.">; @@ -444,7 +440,7 @@ def : ProcessorModel<"btver2", BtVer2Model, FeaturePRFCHW, FeatureAES, FeaturePCLMUL, FeatureBMI, FeatureF16C, FeatureMOVBE, FeatureLZCNT, FeaturePOPCNT, FeatureFastUAMem, - FeatureSlowSHLD, FeatureUseSqrtEst, FeatureUseRecipEst]>; + FeatureSlowSHLD]>; // TODO: We should probably add 'FeatureFastUAMem' to all of the AMD chips. diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index e850e500db6..609973f8971 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -67,12 +67,6 @@ static cl::opt<bool> ExperimentalVectorWideningLegalization( "rather than promotion."), cl::Hidden); -static cl::opt<int> ReciprocalEstimateRefinementSteps( - "x86-recip-refinement-steps", cl::init(1), - cl::desc("Specify the number of Newton-Raphson iterations applied to the " - "result of the hardware reciprocal estimate instruction."), - cl::NotHidden); - // Forward declarations. static SDValue getMOVL(SelectionDAG &DAG, SDLoc dl, EVT VT, SDValue V1, SDValue V2); @@ -12901,29 +12895,31 @@ SDValue X86TargetLowering::getRsqrtEstimate(SDValue Op, DAGCombinerInfo &DCI, unsigned &RefinementSteps, bool &UseOneConstNR) const { - // FIXME: We should use instruction latency models to calculate the cost of - // each potential sequence, but this is very hard to do reliably because - // at least Intel's Core* chips have variable timing based on the number of - // significant digits in the divisor and/or sqrt operand. - if (!Subtarget->useSqrtEst()) - return SDValue(); - EVT VT = Op.getValueType(); + const char *RecipOp; - // SSE1 has rsqrtss and rsqrtps. + // SSE1 has rsqrtss and rsqrtps. AVX adds a 256-bit variant for rsqrtps. // TODO: Add support for AVX512 (v16f32). // It is likely not profitable to do this for f64 because a double-precision // rsqrt estimate with refinement on x86 prior to FMA requires at least 16 // instructions: convert to single, rsqrtss, convert back to double, refine // (3 steps = at least 13 insts). If an 'rsqrtsd' variant was added to the ISA // along with FMA, this could be a throughput win. - if ((Subtarget->hasSSE1() && (VT == MVT::f32 || VT == MVT::v4f32)) || - (Subtarget->hasAVX() && VT == MVT::v8f32)) { - RefinementSteps = 1; - UseOneConstNR = false; - return DCI.DAG.getNode(X86ISD::FRSQRT, SDLoc(Op), VT, Op); - } - return SDValue(); + if (VT == MVT::f32 && Subtarget->hasSSE1()) + RecipOp = "sqrtf"; + else if ((VT == MVT::v4f32 && Subtarget->hasSSE1()) || + (VT == MVT::v8f32 && Subtarget->hasAVX())) + RecipOp = "vec-sqrtf"; + else + return SDValue(); + + TargetRecip Recips = DCI.DAG.getTarget().Options.Reciprocals; + if (!Recips.isEnabled(RecipOp)) + return SDValue(); + + RefinementSteps = Recips.getRefinementSteps(RecipOp); + UseOneConstNR = false; + return DCI.DAG.getNode(X86ISD::FRSQRT, SDLoc(Op), VT, Op); } /// The minimum architected relative accuracy is 2^-12. We need one @@ -12931,15 +12927,9 @@ SDValue X86TargetLowering::getRsqrtEstimate(SDValue Op, SDValue X86TargetLowering::getRecipEstimate(SDValue Op, DAGCombinerInfo &DCI, unsigned &RefinementSteps) const { - // FIXME: We should use instruction latency models to calculate the cost of - // each potential sequence, but this is very hard to do reliably because - // at least Intel's Core* chips have variable timing based on the number of - // significant digits in the divisor. - if (!Subtarget->useReciprocalEst()) - return SDValue(); - EVT VT = Op.getValueType(); - + const char *RecipOp; + // SSE1 has rcpss and rcpps. AVX adds a 256-bit variant for rcpps. // TODO: Add support for AVX512 (v16f32). // It is likely not profitable to do this for f64 because a double-precision @@ -12947,12 +12937,20 @@ SDValue X86TargetLowering::getRecipEstimate(SDValue Op, // 15 instructions: convert to single, rcpss, convert back to double, refine // (3 steps = 12 insts). If an 'rcpsd' variant was added to the ISA // along with FMA, this could be a throughput win. - if ((Subtarget->hasSSE1() && (VT == MVT::f32 || VT == MVT::v4f32)) || - (Subtarget->hasAVX() && VT == MVT::v8f32)) { - RefinementSteps = ReciprocalEstimateRefinementSteps; - return DCI.DAG.getNode(X86ISD::FRCP, SDLoc(Op), VT, Op); - } - return SDValue(); + if (VT == MVT::f32 && Subtarget->hasSSE1()) + RecipOp = "divf"; + else if ((VT == MVT::v4f32 && Subtarget->hasSSE1()) || + (VT == MVT::v8f32 && Subtarget->hasAVX())) + RecipOp = "vec-divf"; + else + return SDValue(); + + TargetRecip Recips = DCI.DAG.getTarget().Options.Reciprocals; + if (!Recips.isEnabled(RecipOp)) + return SDValue(); + + RefinementSteps = Recips.getRefinementSteps(RecipOp); + return DCI.DAG.getNode(X86ISD::FRCP, SDLoc(Op), VT, Op); } /// If we have at least two divisions that use the same divisor, convert to diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp index 1cdab14e034..65e702e7f35 100644 --- a/llvm/lib/Target/X86/X86Subtarget.cpp +++ b/llvm/lib/Target/X86/X86Subtarget.cpp @@ -273,8 +273,6 @@ void X86Subtarget::initializeEnvironment() { LEAUsesAG = false; SlowLEA = false; SlowIncDec = false; - UseSqrtEst = false; - UseReciprocalEst = false; stackAlignment = 4; // FIXME: this is a known good value for Yonah. How about others? MaxInlineSizeThreshold = 128; diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h index 455dd7744d7..27429d050bd 100644 --- a/llvm/lib/Target/X86/X86Subtarget.h +++ b/llvm/lib/Target/X86/X86Subtarget.h @@ -190,16 +190,6 @@ protected: /// True if INC and DEC instructions are slow when writing to flags bool SlowIncDec; - /// Use the RSQRT* instructions to optimize square root calculations. - /// For this to be profitable, the cost of FSQRT and FDIV must be - /// substantially higher than normal FP ops like FADD and FMUL. - bool UseSqrtEst; - - /// Use the RCP* instructions to optimize FP division calculations. - /// For this to be profitable, the cost of FDIV must be - /// substantially higher than normal FP ops like FADD and FMUL. - bool UseReciprocalEst; - /// Processor has AVX-512 PreFetch Instructions bool HasPFI; @@ -377,8 +367,6 @@ public: bool LEAusesAG() const { return LEAUsesAG; } bool slowLEA() const { return SlowLEA; } bool slowIncDec() const { return SlowIncDec; } - bool useSqrtEst() const { return UseSqrtEst; } - bool useReciprocalEst() const { return UseReciprocalEst; } bool hasCDI() const { return HasCDI; } bool hasPFI() const { return HasPFI; } bool hasERI() const { return HasERI; } diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp index 3e5f1d82202..33576f1771f 100644 --- a/llvm/lib/Target/X86/X86TargetMachine.cpp +++ b/llvm/lib/Target/X86/X86TargetMachine.cpp @@ -105,6 +105,13 @@ X86TargetMachine::X86TargetMachine(const Target &T, StringRef TT, StringRef CPU, if (Subtarget.isTargetWin64()) this->Options.TrapUnreachable = true; + // TODO: By default, all reciprocal estimate operations are off because + // that matches the behavior before TargetRecip was added (except for btver2 + // which used subtarget features to enable this type of codegen). + // We should change this to match GCC behavior where everything but + // scalar division estimates are turned on by default with -ffast-math. + this->Options.Reciprocals.setDefaults("all", false, 1); + initAsmInfo(); } |
