CodeGen: Move libcall lowering configuration to subtarget (#168621)

Previously libcall lowering decisions were made directly
in the TargetLowering constructor. Pull these into the subtarget
to facilitate turning LibcallLoweringInfo into a separate analysis
in the future.

Author: arsenm

llvm/include/llvm/CodeGen/LibcallLoweringInfo.h

@@ -13,6 +13,8 @@
 
 namespace llvm {
 
+class TargetSubtargetInfo;
+
 class LibcallLoweringInfo {
 private:
   const RTLIB::RuntimeLibcallsInfo &RTLCI;
@@ -21,7 +23,12 @@ class LibcallLoweringInfo {
       RTLIB::Unsupported};
 
 public:
-  LLVM_ABI LibcallLoweringInfo(const RTLIB::RuntimeLibcallsInfo &RTLCI);
+  LLVM_ABI LibcallLoweringInfo(const RTLIB::RuntimeLibcallsInfo &RTLCI,
+                               const TargetSubtargetInfo &Subtarget);
+
+  const RTLIB::RuntimeLibcallsInfo &getRuntimeLibcallsInfo() const {
+    return RTLCI;
+  }
 
   /// Get the libcall routine name for the specified libcall.
   // FIXME: This should be removed. Only LibcallImpl should have a name.

llvm/include/llvm/CodeGen/TargetSubtargetInfo.h

@@ -38,6 +38,7 @@ class InstrItineraryData;
 struct InstrStage;
 class InstructionSelector;
 class LegalizerInfo;
+class LibcallLoweringInfo;
 class MachineInstr;
 struct MachineSchedPolicy;
 struct MCReadAdvanceEntry;
@@ -139,6 +140,12 @@ class LLVM_ABI TargetSubtargetInfo : public MCSubtargetInfo {
     return nullptr;
   }
 
+  /// Configure the LibcallLoweringInfo for this subtarget. The libcalls will be
+  /// pre-configured with defaults based on RuntimeLibcallsInfo. This may be
+  /// used to override those decisions, such as disambiguating alternative
+  /// implementations.
+  virtual void initLibcallLoweringInfo(LibcallLoweringInfo &Info) const {}
+
   /// Resolve a SchedClass at runtime, where SchedClass identifies an
   /// MCSchedClassDesc with the isVariant property. This may return the ID of
   /// another variant SchedClass, but repeated invocation must quickly terminate

llvm/lib/CodeGen/LibcallLoweringInfo.cpp

@@ -7,11 +7,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/LibcallLoweringInfo.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
 
 using namespace llvm;
 
 LibcallLoweringInfo::LibcallLoweringInfo(
-    const RTLIB::RuntimeLibcallsInfo &RTLCI)
+    const RTLIB::RuntimeLibcallsInfo &RTLCI,
+    const TargetSubtargetInfo &Subtarget)
     : RTLCI(RTLCI) {
   // TODO: This should be generated with lowering predicates, and assert the
   // call is available.
@@ -23,4 +25,6 @@ LibcallLoweringInfo::LibcallLoweringInfo(
         LibcallImpls[LC] = Impl;
     }
   }
+
+  Subtarget.initLibcallLoweringInfo(*this);
 }

llvm/lib/CodeGen/TargetLoweringBase.cpp

@@ -755,7 +755,7 @@ TargetLoweringBase::TargetLoweringBase(const TargetMachine &tm,
       RuntimeLibcallInfo(TM.getTargetTriple(), TM.Options.ExceptionModel,
                          TM.Options.FloatABIType, TM.Options.EABIVersion,
                          TM.Options.MCOptions.getABIName(), TM.Options.VecLib),
-      Libcalls(RuntimeLibcallInfo) {
+      Libcalls(RuntimeLibcallInfo, STI) {
   initActions();
 
   // Perform these initializations only once.

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -518,74 +518,6 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM_,
 
   const Triple &TT = TM.getTargetTriple();
 
-  if (TT.isOSBinFormatMachO()) {
-    // Uses VFP for Thumb libfuncs if available.
-    if (Subtarget->isThumb() && Subtarget->hasVFP2Base() &&
-        Subtarget->hasARMOps() && !Subtarget->useSoftFloat()) {
-      // clang-format off
-      static const struct {
-        const RTLIB::Libcall Op;
-        const RTLIB::LibcallImpl Impl;
-      } LibraryCalls[] = {
-        // Single-precision floating-point arithmetic.
-        { RTLIB::ADD_F32, RTLIB::impl___addsf3vfp },
-        { RTLIB::SUB_F32, RTLIB::impl___subsf3vfp },
-        { RTLIB::MUL_F32, RTLIB::impl___mulsf3vfp },
-        { RTLIB::DIV_F32, RTLIB::impl___divsf3vfp },
-
-        // Double-precision floating-point arithmetic.
-        { RTLIB::ADD_F64, RTLIB::impl___adddf3vfp },
-        { RTLIB::SUB_F64, RTLIB::impl___subdf3vfp },
-        { RTLIB::MUL_F64, RTLIB::impl___muldf3vfp },
-        { RTLIB::DIV_F64, RTLIB::impl___divdf3vfp },
-
-        // Single-precision comparisons.
-        { RTLIB::OEQ_F32, RTLIB::impl___eqsf2vfp },
-        { RTLIB::UNE_F32, RTLIB::impl___nesf2vfp },
-        { RTLIB::OLT_F32, RTLIB::impl___ltsf2vfp },
-        { RTLIB::OLE_F32, RTLIB::impl___lesf2vfp },
-        { RTLIB::OGE_F32, RTLIB::impl___gesf2vfp },
-        { RTLIB::OGT_F32, RTLIB::impl___gtsf2vfp },
-        { RTLIB::UO_F32,  RTLIB::impl___unordsf2vfp },
-
-        // Double-precision comparisons.
-        { RTLIB::OEQ_F64, RTLIB::impl___eqdf2vfp },
-        { RTLIB::UNE_F64, RTLIB::impl___nedf2vfp },
-        { RTLIB::OLT_F64, RTLIB::impl___ltdf2vfp },
-        { RTLIB::OLE_F64, RTLIB::impl___ledf2vfp },
-        { RTLIB::OGE_F64, RTLIB::impl___gedf2vfp },
-        { RTLIB::OGT_F64, RTLIB::impl___gtdf2vfp },
-        { RTLIB::UO_F64,  RTLIB::impl___unorddf2vfp },
-
-        // Floating-point to integer conversions.
-        // i64 conversions are done via library routines even when generating VFP
-        // instructions, so use the same ones.
-        { RTLIB::FPTOSINT_F64_I32, RTLIB::impl___fixdfsivfp },
-        { RTLIB::FPTOUINT_F64_I32, RTLIB::impl___fixunsdfsivfp },
-        { RTLIB::FPTOSINT_F32_I32, RTLIB::impl___fixsfsivfp },
-        { RTLIB::FPTOUINT_F32_I32, RTLIB::impl___fixunssfsivfp },
-
-        // Conversions between floating types.
-        { RTLIB::FPROUND_F64_F32, RTLIB::impl___truncdfsf2vfp },
-        { RTLIB::FPEXT_F32_F64,   RTLIB::impl___extendsfdf2vfp },
-
-        // Integer to floating-point conversions.
-        // i64 conversions are done via library routines even when generating VFP
-        // instructions, so use the same ones.
-        // FIXME: There appears to be some naming inconsistency in ARM libgcc:
-        // e.g., __floatunsidf vs. __floatunssidfvfp.
-        { RTLIB::SINTTOFP_I32_F64, RTLIB::impl___floatsidfvfp },
-        { RTLIB::UINTTOFP_I32_F64, RTLIB::impl___floatunssidfvfp },
-        { RTLIB::SINTTOFP_I32_F32, RTLIB::impl___floatsisfvfp },
-        { RTLIB::UINTTOFP_I32_F32, RTLIB::impl___floatunssisfvfp },
-      };
-      // clang-format on
-
-      for (const auto &LC : LibraryCalls)
-        setLibcallImpl(LC.Op, LC.Impl);
-    }
-  }
-
   if (Subtarget->isThumb1Only())
     addRegisterClass(MVT::i32, &ARM::tGPRRegClass);
   else

llvm/lib/Target/ARM/ARMSubtarget.cpp

@@ -129,6 +129,76 @@ const RegisterBankInfo *ARMSubtarget::getRegBankInfo() const {
   return RegBankInfo.get();
 }
 
+void ARMSubtarget::initLibcallLoweringInfo(LibcallLoweringInfo &Info) const {
+  const Triple &TT = getTargetTriple();
+  if (TT.isOSBinFormatMachO()) {
+    // Uses VFP for Thumb libfuncs if available.
+    if (isThumb() && hasVFP2Base() && hasARMOps() && !useSoftFloat()) {
+      // clang-format off
+      static const struct {
+        const RTLIB::Libcall Op;
+        const RTLIB::LibcallImpl Impl;
+      } LibraryCalls[] = {
+        // Single-precision floating-point arithmetic.
+        { RTLIB::ADD_F32, RTLIB::impl___addsf3vfp },
+        { RTLIB::SUB_F32, RTLIB::impl___subsf3vfp },
+        { RTLIB::MUL_F32, RTLIB::impl___mulsf3vfp },
+        { RTLIB::DIV_F32, RTLIB::impl___divsf3vfp },
+
+        // Double-precision floating-point arithmetic.
+        { RTLIB::ADD_F64, RTLIB::impl___adddf3vfp },
+        { RTLIB::SUB_F64, RTLIB::impl___subdf3vfp },
+        { RTLIB::MUL_F64, RTLIB::impl___muldf3vfp },
+        { RTLIB::DIV_F64, RTLIB::impl___divdf3vfp },
+
+        // Single-precision comparisons.
+        { RTLIB::OEQ_F32, RTLIB::impl___eqsf2vfp },
+        { RTLIB::UNE_F32, RTLIB::impl___nesf2vfp },
+        { RTLIB::OLT_F32, RTLIB::impl___ltsf2vfp },
+        { RTLIB::OLE_F32, RTLIB::impl___lesf2vfp },
+        { RTLIB::OGE_F32, RTLIB::impl___gesf2vfp },
+        { RTLIB::OGT_F32, RTLIB::impl___gtsf2vfp },
+        { RTLIB::UO_F32,  RTLIB::impl___unordsf2vfp },
+
+        // Double-precision comparisons.
+        { RTLIB::OEQ_F64, RTLIB::impl___eqdf2vfp },
+        { RTLIB::UNE_F64, RTLIB::impl___nedf2vfp },
+        { RTLIB::OLT_F64, RTLIB::impl___ltdf2vfp },
+        { RTLIB::OLE_F64, RTLIB::impl___ledf2vfp },
+        { RTLIB::OGE_F64, RTLIB::impl___gedf2vfp },
+        { RTLIB::OGT_F64, RTLIB::impl___gtdf2vfp },
+        { RTLIB::UO_F64,  RTLIB::impl___unorddf2vfp },
+
+        // Floating-point to integer conversions.
+        // i64 conversions are done via library routines even when generating VFP
+        // instructions, so use the same ones.
+        { RTLIB::FPTOSINT_F64_I32, RTLIB::impl___fixdfsivfp },
+        { RTLIB::FPTOUINT_F64_I32, RTLIB::impl___fixunsdfsivfp },
+        { RTLIB::FPTOSINT_F32_I32, RTLIB::impl___fixsfsivfp },
+        { RTLIB::FPTOUINT_F32_I32, RTLIB::impl___fixunssfsivfp },
+
+        // Conversions between floating types.
+        { RTLIB::FPROUND_F64_F32, RTLIB::impl___truncdfsf2vfp },
+        { RTLIB::FPEXT_F32_F64,   RTLIB::impl___extendsfdf2vfp },
+
+        // Integer to floating-point conversions.
+        // i64 conversions are done via library routines even when generating VFP
+        // instructions, so use the same ones.
+        // FIXME: There appears to be some naming inconsistency in ARM libgcc:
+        // e.g., __floatunsidf vs. __floatunssidfvfp.
+        { RTLIB::SINTTOFP_I32_F64, RTLIB::impl___floatsidfvfp },
+        { RTLIB::UINTTOFP_I32_F64, RTLIB::impl___floatunssidfvfp },
+        { RTLIB::SINTTOFP_I32_F32, RTLIB::impl___floatsisfvfp },
+        { RTLIB::UINTTOFP_I32_F32, RTLIB::impl___floatunssisfvfp },
+      };
+      // clang-format on
+
+      for (const auto &LC : LibraryCalls)
+        Info.setLibcallImpl(LC.Op, LC.Impl);
+    }
+  }
+}
+
 bool ARMSubtarget::isXRaySupported() const {
   // We don't currently suppport Thumb, but Windows requires Thumb.
   return hasV6Ops() && hasARMOps() && !isTargetWindows();

llvm/lib/Target/ARM/ARMSubtarget.h

@@ -258,6 +258,7 @@ class ARMSubtarget : public ARMGenSubtargetInfo {
   InstructionSelector *getInstructionSelector() const override;
   const LegalizerInfo *getLegalizerInfo() const override;
   const RegisterBankInfo *getRegBankInfo() const override;
+  void initLibcallLoweringInfo(LibcallLoweringInfo &Info) const override;
 
 private:
   ARMSelectionDAGInfo TSInfo;

llvm/lib/Target/MSP430/MSP430ISelLowering.cpp

@@ -148,68 +148,6 @@ MSP430TargetLowering::MSP430TargetLowering(const TargetMachine &TM,
   setOperationAction(ISD::VACOPY,           MVT::Other, Expand);
   setOperationAction(ISD::JumpTable,        MVT::i16,   Custom);
 
-  if (STI.hasHWMult16()) {
-    const struct {
-      const RTLIB::Libcall Op;
-      const RTLIB::LibcallImpl Impl;
-    } LibraryCalls[] = {
-        // Integer Multiply - EABI Table 9
-        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_hw},
-        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_hw},
-        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_hw},
-        // TODO The __mspabi_mpysl*_hw functions ARE implemented in libgcc
-        // TODO The __mspabi_mpyul*_hw functions ARE implemented in libgcc
-    };
-    for (const auto &LC : LibraryCalls) {
-      setLibcallImpl(LC.Op, LC.Impl);
-    }
-  } else if (STI.hasHWMult32()) {
-    const struct {
-      const RTLIB::Libcall Op;
-      const RTLIB::LibcallImpl Impl;
-    } LibraryCalls[] = {
-        // Integer Multiply - EABI Table 9
-        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_hw},
-        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_hw32},
-        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_hw32},
-        // TODO The __mspabi_mpysl*_hw32 functions ARE implemented in libgcc
-        // TODO The __mspabi_mpyul*_hw32 functions ARE implemented in libgcc
-    };
-    for (const auto &LC : LibraryCalls) {
-      setLibcallImpl(LC.Op, LC.Impl);
-    }
-  } else if (STI.hasHWMultF5()) {
-    const struct {
-      const RTLIB::Libcall Op;
-      const RTLIB::LibcallImpl Impl;
-    } LibraryCalls[] = {
-        // Integer Multiply - EABI Table 9
-        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_f5hw},
-        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_f5hw},
-        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_f5hw},
-        // TODO The __mspabi_mpysl*_f5hw functions ARE implemented in libgcc
-        // TODO The __mspabi_mpyul*_f5hw functions ARE implemented in libgcc
-    };
-    for (const auto &LC : LibraryCalls) {
-      setLibcallImpl(LC.Op, LC.Impl);
-    }
-  } else { // NoHWMult
-    const struct {
-      const RTLIB::Libcall Op;
-      const RTLIB::LibcallImpl Impl;
-    } LibraryCalls[] = {
-        // Integer Multiply - EABI Table 9
-        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi},
-        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl},
-        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll},
-        // The __mspabi_mpysl* functions are NOT implemented in libgcc
-        // The __mspabi_mpyul* functions are NOT implemented in libgcc
-    };
-    for (const auto &LC : LibraryCalls) {
-      setLibcallImpl(LC.Op, LC.Impl);
-    }
-  }
-
   setMinFunctionAlignment(Align(2));
   setPrefFunctionAlignment(Align(2));
   setMaxAtomicSizeInBitsSupported(0);

llvm/lib/Target/MSP430/MSP430Subtarget.cpp

@@ -68,3 +68,67 @@ MSP430Subtarget::~MSP430Subtarget() = default;
 const SelectionDAGTargetInfo *MSP430Subtarget::getSelectionDAGInfo() const {
   return TSInfo.get();
 }
+
+void MSP430Subtarget::initLibcallLoweringInfo(LibcallLoweringInfo &Info) const {
+  if (hasHWMult16()) {
+    const struct {
+      const RTLIB::Libcall Op;
+      const RTLIB::LibcallImpl Impl;
+    } LibraryCalls[] = {
+        // Integer Multiply - EABI Table 9
+        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_hw},
+        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_hw},
+        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_hw},
+        // TODO The __mspabi_mpysl*_hw functions ARE implemented in libgcc
+        // TODO The __mspabi_mpyul*_hw functions ARE implemented in libgcc
+    };
+    for (const auto &LC : LibraryCalls) {
+      Info.setLibcallImpl(LC.Op, LC.Impl);
+    }
+  } else if (hasHWMult32()) {
+    const struct {
+      const RTLIB::Libcall Op;
+      const RTLIB::LibcallImpl Impl;
+    } LibraryCalls[] = {
+        // Integer Multiply - EABI Table 9
+        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_hw},
+        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_hw32},
+        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_hw32},
+        // TODO The __mspabi_mpysl*_hw32 functions ARE implemented in libgcc
+        // TODO The __mspabi_mpyul*_hw32 functions ARE implemented in libgcc
+    };
+    for (const auto &LC : LibraryCalls) {
+      Info.setLibcallImpl(LC.Op, LC.Impl);
+    }
+  } else if (hasHWMultF5()) {
+    const struct {
+      const RTLIB::Libcall Op;
+      const RTLIB::LibcallImpl Impl;
+    } LibraryCalls[] = {
+        // Integer Multiply - EABI Table 9
+        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi_f5hw},
+        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl_f5hw},
+        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll_f5hw},
+        // TODO The __mspabi_mpysl*_f5hw functions ARE implemented in libgcc
+        // TODO The __mspabi_mpyul*_f5hw functions ARE implemented in libgcc
+    };
+    for (const auto &LC : LibraryCalls) {
+      Info.setLibcallImpl(LC.Op, LC.Impl);
+    }
+  } else { // NoHWMult
+    const struct {
+      const RTLIB::Libcall Op;
+      const RTLIB::LibcallImpl Impl;
+    } LibraryCalls[] = {
+        // Integer Multiply - EABI Table 9
+        {RTLIB::MUL_I16, RTLIB::impl___mspabi_mpyi},
+        {RTLIB::MUL_I32, RTLIB::impl___mspabi_mpyl},
+        {RTLIB::MUL_I64, RTLIB::impl___mspabi_mpyll},
+        // The __mspabi_mpysl* functions are NOT implemented in libgcc
+        // The __mspabi_mpyul* functions are NOT implemented in libgcc
+    };
+    for (const auto &LC : LibraryCalls) {
+      Info.setLibcallImpl(LC.Op, LC.Impl);
+    }
+  }
+}

llvm/lib/Target/MSP430/MSP430Subtarget.h

@@ -74,6 +74,8 @@ class MSP430Subtarget : public MSP430GenSubtargetInfo {
   }
 
   const SelectionDAGTargetInfo *getSelectionDAGInfo() const override;
+
+  void initLibcallLoweringInfo(LibcallLoweringInfo &Info) const override;
 };
 } // End llvm namespace