RuntimeLibcalls: Remove table of soft float compare cond codes (#146082)

Previously we had a table of entries for every Libcall for
the comparison to use against an integer 0 if it was a soft
float compare function. This was only relevant to a handful of
opcodes, so it was wasteful. Now that we can distinguish the
abstract libcall for the compare with the concrete implementation,
we can just directly hardcode the comparison against the libcall
impl without this configuration system.

Author: arsenm

llvm/include/llvm/CodeGen/RuntimeLibcallUtil.h

@@ -117,9 +117,6 @@ LLVM_ABI Libcall getMEMMOVE_ELEMENT_UNORDERED_ATOMIC(uint64_t ElementSize);
 /// UNKNOW_LIBCALL if there is none.
 LLVM_ABI Libcall getMEMSET_ELEMENT_UNORDERED_ATOMIC(uint64_t ElementSize);
 
-/// Initialize the default condition code on the libcalls.
-LLVM_ABI void initCmpLibcallCCs(ISD::CondCode *CmpLibcallCCs);
-
 } // namespace RTLIB
 } // namespace llvm
 

llvm/include/llvm/CodeGen/TargetLowering.h

@@ -3571,19 +3571,10 @@ class LLVM_ABI TargetLoweringBase {
 
   const char *getMemcpyName() const { return Libcalls.getMemcpyName(); }
 
-  /// Override the default CondCode to be used to test the result of the
-  /// comparison libcall against zero.
-  /// FIXME: This should be removed
-  void setCmpLibcallCC(RTLIB::Libcall Call, CmpInst::Predicate Pred) {
-    Libcalls.setSoftFloatCmpLibcallPredicate(Call, Pred);
-  }
-
-  /// Get the CondCode that's to be used to test the result of the comparison
-  /// libcall against zero.
-  CmpInst::Predicate
-  getSoftFloatCmpLibcallPredicate(RTLIB::Libcall Call) const {
-    return Libcalls.getSoftFloatCmpLibcallPredicate(Call);
-  }
+  /// Get the comparison predicate that's to be used to test the result of the
+  /// comparison libcall against zero. This should only be used with
+  /// floating-point compare libcalls.
+  ISD::CondCode getSoftFloatCmpLibcallPredicate(RTLIB::LibcallImpl Call) const;
 
   /// Set the CallingConv that should be used for the specified libcall.
   void setLibcallImplCallingConv(RTLIB::LibcallImpl Call, CallingConv::ID CC) {

llvm/include/llvm/IR/RuntimeLibcalls.h

@@ -59,8 +59,6 @@ struct RuntimeLibcallsInfo {
       ExceptionHandling ExceptionModel = ExceptionHandling::None,
       FloatABI::ABIType FloatABI = FloatABI::Default,
       EABI EABIVersion = EABI::Default, StringRef ABIName = "") {
-    initSoftFloatCmpLibcallPredicates();
-
     // FIXME: The ExceptionModel parameter is to handle the field in
     // TargetOptions. This interface fails to distinguish the forced disable
     // case for targets which support exceptions by default. This should
@@ -114,22 +112,6 @@ struct RuntimeLibcallsInfo {
     return ArrayRef(LibcallImpls).drop_back();
   }
 
-  /// Get the comparison predicate that's to be used to test the result of the
-  /// comparison libcall against zero. This should only be used with
-  /// floating-point compare libcalls.
-  // FIXME: This should be a function of RTLIB::LibcallImpl
-  CmpInst::Predicate
-  getSoftFloatCmpLibcallPredicate(RTLIB::Libcall Call) const {
-    return SoftFloatCompareLibcallPredicates[Call];
-  }
-
-  // FIXME: This should be removed. This should be private constant.
-  // FIXME: This should be a function of RTLIB::LibcallImpl
-  void setSoftFloatCmpLibcallPredicate(RTLIB::Libcall Call,
-                                       CmpInst::Predicate Pred) {
-    SoftFloatCompareLibcallPredicates[Call] = Pred;
-  }
-
   /// Return a function name compatible with RTLIB::MEMCPY, or nullptr if fully
   /// unsupported.
   const char *getMemcpyName() const {
@@ -140,6 +122,11 @@ struct RuntimeLibcallsInfo {
     return getLibcallName(RTLIB::MEMMOVE);
   }
 
+  /// Return the libcall provided by \p Impl
+  static RTLIB::Libcall getLibcallFromImpl(RTLIB::LibcallImpl Impl) {
+    return ImplToLibcall[Impl];
+  }
+
 private:
   static const RTLIB::LibcallImpl
       DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1];
@@ -155,14 +142,6 @@ struct RuntimeLibcallsInfo {
   /// implementation.;
   CallingConv::ID LibcallImplCallingConvs[RTLIB::NumLibcallImpls] = {};
 
-  /// The condition type that should be used to test the result of each of the
-  /// soft floating-point comparison libcall against integer zero.
-  ///
-  // FIXME: This is only relevant for the handful of floating-point comparison
-  // runtime calls; it's excessive to have a table entry for every single
-  // opcode.
-  CmpInst::Predicate SoftFloatCompareLibcallPredicates[RTLIB::UNKNOWN_LIBCALL];
-
   /// Names of concrete implementations of runtime calls. e.g. __ashlsi3 for
   /// SHL_I32
   LLVM_ABI static const char *const LibCallImplNames[RTLIB::NumLibcallImpls];
@@ -200,8 +179,6 @@ struct RuntimeLibcallsInfo {
   /// Generated by tablegen.
   void setTargetRuntimeLibcallSets(const Triple &TT);
 
-  LLVM_ABI void initSoftFloatCmpLibcallPredicates();
-
   /// Set default libcall names. If a target wants to opt-out of a libcall it
   /// should be placed here.
   LLVM_ABI void initLibcalls(const Triple &TT, ExceptionHandling ExceptionModel,

llvm/include/llvm/IR/RuntimeLibcalls.td

@@ -1176,8 +1176,8 @@ def __aeabi_dsub : RuntimeLibcallImpl<SUB_F64>; // CallingConv::ARM_AAPCS
 
 // Double-precision floating-point comparison helper functions
 // RTABI chapter 4.1.2, Table 3
-def __aeabi_dcmpeq__ne : RuntimeLibcallImpl<OEQ_F64, "__aeabi_dcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
-def __aeabi_dcmpeq__eq : RuntimeLibcallImpl<UNE_F64, "__aeabi_dcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_EQ
+def __aeabi_dcmpeq__oeq : RuntimeLibcallImpl<OEQ_F64, "__aeabi_dcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
+def __aeabi_dcmpeq__une : RuntimeLibcallImpl<UNE_F64, "__aeabi_dcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_EQ
 def __aeabi_dcmplt : RuntimeLibcallImpl<OLT_F64>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
 def __aeabi_dcmple : RuntimeLibcallImpl<OLE_F64>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
 def __aeabi_dcmpge : RuntimeLibcallImpl<OGE_F64>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
@@ -1193,8 +1193,8 @@ def __aeabi_fsub : RuntimeLibcallImpl<SUB_F32>; // CallingConv::ARM_AAPCS
 
 // Single-precision floating-point comparison helper functions
 // RTABI chapter 4.1.2, Table 5
-def __aeabi_fcmpeq__ne : RuntimeLibcallImpl<OEQ_F32, "__aeabi_fcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
-def __aeabi_fcmpeq__eq : RuntimeLibcallImpl<UNE_F32, "__aeabi_fcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_EQ
+def __aeabi_fcmpeq__oeq : RuntimeLibcallImpl<OEQ_F32, "__aeabi_fcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
+def __aeabi_fcmpeq__une : RuntimeLibcallImpl<UNE_F32, "__aeabi_fcmpeq">; // CallingConv::ARM_AAPCS, CmpInst::ICMP_EQ
 def __aeabi_fcmplt : RuntimeLibcallImpl<OLT_F32>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
 def __aeabi_fcmple : RuntimeLibcallImpl<OLE_F32>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE
 def __aeabi_fcmpge : RuntimeLibcallImpl<OGE_F32>; // CallingConv::ARM_AAPCS, CmpInst::ICMP_NE

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -424,7 +424,13 @@ void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
   NewLHS = Call.first;
   NewRHS = DAG.getConstant(0, dl, RetVT);
 
-  CCCode = getICmpCondCode(getSoftFloatCmpLibcallPredicate(LC1));
+  RTLIB::LibcallImpl LC1Impl = getLibcallImpl(LC1);
+  if (LC1Impl == RTLIB::Unsupported) {
+    reportFatalUsageError(
+        "no libcall available to soften floating-point compare");
+  }
+
+  CCCode = getSoftFloatCmpLibcallPredicate(LC1Impl);
   if (ShouldInvertCC) {
     assert(RetVT.isInteger());
     CCCode = getSetCCInverse(CCCode, RetVT);
@@ -434,6 +440,12 @@ void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
     // Update Chain.
     Chain = Call.second;
   } else {
+    RTLIB::LibcallImpl LC2Impl = getLibcallImpl(LC2);
+    if (LC2Impl == RTLIB::Unsupported) {
+      reportFatalUsageError(
+          "no libcall available to soften floating-point compare");
+    }
+
     assert(CCCode == (ShouldInvertCC ? ISD::SETEQ : ISD::SETNE) &&
            "unordered call should be simple boolean");
 
@@ -446,7 +458,7 @@ void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
 
     SDValue Tmp = DAG.getSetCC(dl, SetCCVT, NewLHS, NewRHS, CCCode);
     auto Call2 = makeLibCall(DAG, LC2, RetVT, Ops, CallOptions, dl, Chain);
-    CCCode = getICmpCondCode(getSoftFloatCmpLibcallPredicate(LC2));
+    CCCode = getSoftFloatCmpLibcallPredicate(LC2Impl);
     if (ShouldInvertCC)
       CCCode = getSetCCInverse(CCCode, RetVT);
     NewLHS = DAG.getSetCC(dl, SetCCVT, Call2.first, NewRHS, CCCode);

llvm/lib/CodeGen/TargetLoweringBase.cpp

@@ -609,37 +609,79 @@ RTLIB::Libcall RTLIB::getMEMSET_ELEMENT_UNORDERED_ATOMIC(uint64_t ElementSize) {
   }
 }
 
-void RTLIB::initCmpLibcallCCs(ISD::CondCode *CmpLibcallCCs) {
-  std::fill(CmpLibcallCCs, CmpLibcallCCs + RTLIB::UNKNOWN_LIBCALL,
-            ISD::SETCC_INVALID);
-  CmpLibcallCCs[RTLIB::OEQ_F32] = ISD::SETEQ;
-  CmpLibcallCCs[RTLIB::OEQ_F64] = ISD::SETEQ;
-  CmpLibcallCCs[RTLIB::OEQ_F128] = ISD::SETEQ;
-  CmpLibcallCCs[RTLIB::OEQ_PPCF128] = ISD::SETEQ;
-  CmpLibcallCCs[RTLIB::UNE_F32] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UNE_F64] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UNE_F128] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UNE_PPCF128] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::OGE_F32] = ISD::SETGE;
-  CmpLibcallCCs[RTLIB::OGE_F64] = ISD::SETGE;
-  CmpLibcallCCs[RTLIB::OGE_F128] = ISD::SETGE;
-  CmpLibcallCCs[RTLIB::OGE_PPCF128] = ISD::SETGE;
-  CmpLibcallCCs[RTLIB::OLT_F32] = ISD::SETLT;
-  CmpLibcallCCs[RTLIB::OLT_F64] = ISD::SETLT;
-  CmpLibcallCCs[RTLIB::OLT_F128] = ISD::SETLT;
-  CmpLibcallCCs[RTLIB::OLT_PPCF128] = ISD::SETLT;
-  CmpLibcallCCs[RTLIB::OLE_F32] = ISD::SETLE;
-  CmpLibcallCCs[RTLIB::OLE_F64] = ISD::SETLE;
-  CmpLibcallCCs[RTLIB::OLE_F128] = ISD::SETLE;
-  CmpLibcallCCs[RTLIB::OLE_PPCF128] = ISD::SETLE;
-  CmpLibcallCCs[RTLIB::OGT_F32] = ISD::SETGT;
-  CmpLibcallCCs[RTLIB::OGT_F64] = ISD::SETGT;
-  CmpLibcallCCs[RTLIB::OGT_F128] = ISD::SETGT;
-  CmpLibcallCCs[RTLIB::OGT_PPCF128] = ISD::SETGT;
-  CmpLibcallCCs[RTLIB::UO_F32] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UO_F64] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UO_F128] = ISD::SETNE;
-  CmpLibcallCCs[RTLIB::UO_PPCF128] = ISD::SETNE;
+ISD::CondCode TargetLoweringBase::getSoftFloatCmpLibcallPredicate(
+    RTLIB::LibcallImpl Impl) const {
+  switch (Impl) {
+  case RTLIB::__aeabi_dcmpeq__une:
+  case RTLIB::__aeabi_fcmpeq__une:
+    // Usage in the eq case, so we have to invert the comparison.
+    return ISD::SETEQ;
+  case RTLIB::__aeabi_dcmpeq__oeq:
+  case RTLIB::__aeabi_fcmpeq__oeq:
+    // Normal comparison to boolean value.
+    return ISD::SETNE;
+  case RTLIB::__aeabi_dcmplt:
+  case RTLIB::__aeabi_dcmple:
+  case RTLIB::__aeabi_dcmpge:
+  case RTLIB::__aeabi_dcmpgt:
+  case RTLIB::__aeabi_dcmpun:
+  case RTLIB::__aeabi_fcmplt:
+  case RTLIB::__aeabi_fcmple:
+  case RTLIB::__aeabi_fcmpge:
+  case RTLIB::__aeabi_fcmpgt:
+    /// The AEABI versions return a typical boolean value, so we can compare
+    /// against the integer result as simply != 0.
+    return ISD::SETNE;
+  default:
+    break;
+  }
+
+  // Assume libgcc/compiler-rt behavior. Most of the cases are really aliases of
+  // each other, and return a 3-way comparison style result of -1, 0, or 1
+  // depending on lt/eq/gt.
+  //
+  // FIXME: It would be cleaner to directly express this as a 3-way comparison
+  // soft FP libcall instead of individual compares.
+  RTLIB::Libcall LC = RTLIB::RuntimeLibcallsInfo::getLibcallFromImpl(Impl);
+  switch (LC) {
+  case RTLIB::OEQ_F32:
+  case RTLIB::OEQ_F64:
+  case RTLIB::OEQ_F128:
+  case RTLIB::OEQ_PPCF128:
+    return ISD::SETEQ;
+  case RTLIB::UNE_F32:
+  case RTLIB::UNE_F64:
+  case RTLIB::UNE_F128:
+  case RTLIB::UNE_PPCF128:
+    return ISD::SETNE;
+  case RTLIB::OGE_F32:
+  case RTLIB::OGE_F64:
+  case RTLIB::OGE_F128:
+  case RTLIB::OGE_PPCF128:
+    return ISD::SETGE;
+  case RTLIB::OLT_F32:
+  case RTLIB::OLT_F64:
+  case RTLIB::OLT_F128:
+  case RTLIB::OLT_PPCF128:
+    return ISD::SETLT;
+  case RTLIB::OLE_F32:
+  case RTLIB::OLE_F64:
+  case RTLIB::OLE_F128:
+  case RTLIB::OLE_PPCF128:
+    return ISD::SETLE;
+  case RTLIB::OGT_F32:
+  case RTLIB::OGT_F64:
+  case RTLIB::OGT_F128:
+  case RTLIB::OGT_PPCF128:
+    return ISD::SETGT;
+  case RTLIB::UO_F32:
+  case RTLIB::UO_F64:
+  case RTLIB::UO_F128:
+  case RTLIB::UO_PPCF128:
+    return ISD::SETNE;
+  default:
+    llvm_unreachable("not a compare libcall");
+  }
 }
 
 /// NOTE: The TargetMachine owns TLOF.
@@ -678,8 +720,6 @@ TargetLoweringBase::TargetLoweringBase(const TargetMachine &tm)
 
   MinCmpXchgSizeInBits = 0;
   SupportsUnalignedAtomics = false;
-
-  RTLIB::initCmpLibcallCCs(CmpLibcallCCs);
 }
 
 // Define the virtual destructor out-of-line to act as a key method to anchor

llvm/lib/IR/RuntimeLibcalls.cpp

@@ -100,37 +100,6 @@ static void setARMLibcallNames(RuntimeLibcallsInfo &Info, const Triple &TT,
   }
 }
 
-void RuntimeLibcallsInfo::initSoftFloatCmpLibcallPredicates() {
-  SoftFloatCompareLibcallPredicates[RTLIB::OEQ_F32] = CmpInst::ICMP_EQ;
-  SoftFloatCompareLibcallPredicates[RTLIB::OEQ_F64] = CmpInst::ICMP_EQ;
-  SoftFloatCompareLibcallPredicates[RTLIB::OEQ_F128] = CmpInst::ICMP_EQ;
-  SoftFloatCompareLibcallPredicates[RTLIB::OEQ_PPCF128] = CmpInst::ICMP_EQ;
-  SoftFloatCompareLibcallPredicates[RTLIB::UNE_F32] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UNE_F64] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UNE_F128] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UNE_PPCF128] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGE_F32] = CmpInst::ICMP_SGE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGE_F64] = CmpInst::ICMP_SGE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGE_F128] = CmpInst::ICMP_SGE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGE_PPCF128] = CmpInst::ICMP_SGE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLT_F32] = CmpInst::ICMP_SLT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLT_F64] = CmpInst::ICMP_SLT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLT_F128] = CmpInst::ICMP_SLT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLT_PPCF128] = CmpInst::ICMP_SLT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLE_F32] = CmpInst::ICMP_SLE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLE_F64] = CmpInst::ICMP_SLE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLE_F128] = CmpInst::ICMP_SLE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OLE_PPCF128] = CmpInst::ICMP_SLE;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGT_F32] = CmpInst::ICMP_SGT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGT_F64] = CmpInst::ICMP_SGT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGT_F128] = CmpInst::ICMP_SGT;
-  SoftFloatCompareLibcallPredicates[RTLIB::OGT_PPCF128] = CmpInst::ICMP_SGT;
-  SoftFloatCompareLibcallPredicates[RTLIB::UO_F32] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UO_F64] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UO_F128] = CmpInst::ICMP_NE;
-  SoftFloatCompareLibcallPredicates[RTLIB::UO_PPCF128] = CmpInst::ICMP_NE;
-}
-
 static void setLongDoubleIsF128Libm(RuntimeLibcallsInfo &Info,
                                     bool FiniteOnlyFuncs = false) {
   Info.setLibcallImpl(RTLIB::REM_F128, RTLIB::fmodf128);