RuntimeLibcalls: Really move default libcall handling to tablegen

Hack in the default setting so it's consistently generated like
the other cases. Maintain a list of targets where this applies.
The alternative would require new infrastructure to sort the system
library initialization in some way.

I wanted the unhandled target case to be treated as a fatal
error, but it turns out there's a hack in IRSymtab using
RuntimeLibcalls, which will fail out in many tests that
do not have a triple set. Many of the failures are simply
running llvm-as with no triple, which probably should not
depend on knowing an accurate set of calls.

Author: arsenm

llvm/include/llvm/IR/RuntimeLibcalls.h

@@ -137,9 +137,6 @@ struct RuntimeLibcallsInfo {
   RTLIB::LibcallImpl getSupportedLibcallImpl(StringRef FuncName) const;
 
 private:
-  static const RTLIB::LibcallImpl
-      DefaultLibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1];
-
   /// Stores the implementation choice for each each libcall.
   RTLIB::LibcallImpl LibcallImpls[RTLIB::UNKNOWN_LIBCALL + 1] = {
       RTLIB::Unsupported};
@@ -197,8 +194,6 @@ struct RuntimeLibcallsInfo {
     return hasSinCos(TT) || TT.isPS();
   }
 
-  LLVM_ABI void initDefaultLibCallImpls();
-
   /// Generated by tablegen.
   void setTargetRuntimeLibcallSets(const Triple &TT,
                                    FloatABI::ABIType FloatABI);

llvm/include/llvm/IR/RuntimeLibcalls.td

@@ -1606,7 +1606,9 @@ def HexagonSystemLibrary
     (add (sub DefaultLibcallImpls32,
     __adddf3, __divsf3, __udivsi3, __udivdi3,
     __umoddi3, __divdf3, __muldf3, __divsi3, __subdf3, sqrtf,
-    __divdi3, __umodsi3, __moddi3, __modsi3), HexagonLibcalls)>;
+    __divdi3, __umodsi3, __moddi3, __modsi3), HexagonLibcalls,
+    LibmHasSinCosF32, LibmHasSinCosF64, LibmHasSinCosF128,
+    exp10f, exp10, exp10l_f128)>;
 
 //===----------------------------------------------------------------------===//
 // Lanai Runtime Libcalls
@@ -1819,6 +1821,7 @@ defvar MSP430DefaultOptOut = [
 def MSP430SystemLibrary
     : SystemRuntimeLibrary<isMSP430,
     (add (sub DefaultRuntimeLibcallImpls, MSP430DefaultOptOut),
+      exp10f, exp10, exp10l_f128,
 
       // Floating point conversions - EABI Table 6
       __mspabi_cvtdf,
@@ -2164,8 +2167,12 @@ def __memcpy_4 : RuntimeLibcallImpl<MEMCPY_ALIGN_4>;
 
 def isXCore : RuntimeLibcallPredicate<"TT.getArch() == Triple::xcore">;
 def XCoreSystemLibrary
-    : SystemRuntimeLibrary<isXCore, (add DefaultRuntimeLibcallImpls,
-                                        __memcpy_4)>;
+    : SystemRuntimeLibrary<isXCore,
+    (add DefaultRuntimeLibcallImpls,
+         exp10f, exp10, exp10l_f128,
+         __memcpy_4,
+         LibcallImpls<(add LibmF128Libcalls, LibmF128FiniteLibcalls), isGNUEnvironment>
+)>;
 
 //===----------------------------------------------------------------------===//
 // ZOS Runtime Libcalls
@@ -2282,3 +2289,26 @@ def WasmSystemLibrary
            CompilerRTOnlyInt64Libcalls, CompilerRTOnlyInt128Libcalls,
            exp10f, exp10,
            emscripten_return_address)>;
+
+//===----------------------------------------------------------------------===//
+// Legacy Default Runtime Libcalls
+//===----------------------------------------------------------------------===//
+
+// TODO: Should make every target explicit.
+def isDefaultLibcallArch : RuntimeLibcallPredicate<[{
+  TT.isMIPS() || TT.isLoongArch() || TT.isVE() || TT.isBPF() ||
+  TT.getArch() == Triple::csky || TT.getArch() == Triple::arc ||
+  TT.getArch() == Triple::m68k ||  TT.getArch() == Triple::xtensa ||
+  (TT.isSystemZ() && !TT.isOSzOS())
+}]>;
+
+
+def isArch64Bit : RuntimeLibcallPredicate<[{TT.isArch64Bit()}]>;
+def LegacyDefaultSystemLibrary
+    : SystemRuntimeLibrary<isDefaultLibcallArch,
+      (add DefaultRuntimeLibcallImpls,
+         LibmHasSinCosF32, LibmHasSinCosF64, LibmHasSinCosF128,
+         exp10f, exp10, exp10l_f128,
+         __powisf2, __powidf2, __powitf2_f128,
+         LibcallImpls<(add Int128RTLibcalls), isArch64Bit>
+)>;

llvm/lib/IR/RuntimeLibcalls.cpp

@@ -8,6 +8,9 @@
 
 #include "llvm/IR/RuntimeLibcalls.h"
 #include "llvm/ADT/StringTable.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "runtime-libcalls-info"
 
 using namespace llvm;
 using namespace RTLIB;
@@ -62,12 +65,6 @@ static void setARMLibcallNames(RuntimeLibcallsInfo &Info, const Triple &TT,
     Info.setLibcallImplCallingConv(Impl, CallingConv::ARM_AAPCS);
 }
 
-void RTLIB::RuntimeLibcallsInfo::initDefaultLibCallImpls() {
-  std::memcpy(LibcallImpls, DefaultLibcallImpls, sizeof(LibcallImpls));
-  static_assert(sizeof(LibcallImpls) == sizeof(DefaultLibcallImpls),
-                "libcall array size should match");
-}
-
 /// Set default libcall names. If a target wants to opt-out of a libcall it
 /// should be placed here.
 void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
@@ -76,10 +73,6 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
                                        EABI EABIVersion, StringRef ABIName) {
   setTargetRuntimeLibcallSets(TT, FloatABI);
 
-  // Early exit for targets that have fully ported to tablegen.
-  if (TT.isAMDGPU() || TT.isNVPTX() || TT.isWasm())
-    return;
-
   if (TT.isX86() || TT.isVE() || TT.isARM() || TT.isThumb()) {
     if (ExceptionModel == ExceptionHandling::SjLj)
       setLibcallImpl(RTLIB::UNWIND_RESUME, RTLIB::_Unwind_SjLj_Resume);
@@ -92,47 +85,18 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
     // FIXME: What about other targets?
     setLibcallImpl(RTLIB::FPEXT_F16_F32, RTLIB::__extendhfsf2);
     setLibcallImpl(RTLIB::FPROUND_F32_F16, RTLIB::__truncsfhf2);
-
-    if (!darwinHasExp10(TT)) {
-      setLibcallImpl(RTLIB::EXP10_F32, RTLIB::Unsupported);
-      setLibcallImpl(RTLIB::EXP10_F64, RTLIB::Unsupported);
-    }
   }
 
   if (TT.isOSOpenBSD()) {
     setLibcallImpl(RTLIB::STACKPROTECTOR_CHECK_FAIL, RTLIB::Unsupported);
     setLibcallImpl(RTLIB::STACK_SMASH_HANDLER, RTLIB::__stack_smash_handler);
   }
 
-  // Skip default manual processing for targets that have been mostly ported to
-  // tablegen for now. Eventually the rest of this should be deleted.
-  if (TT.isX86() || TT.isAArch64() || TT.isWasm() || TT.isPPC())
-    return;
-
   if (TT.isARM() || TT.isThumb()) {
     setARMLibcallNames(*this, TT, FloatABI, EABIVersion);
     return;
   }
 
-  if (hasSinCos(TT)) {
-    setLibcallImpl(RTLIB::SINCOS_F32, RTLIB::sincosf);
-    setLibcallImpl(RTLIB::SINCOS_F64, RTLIB::sincos);
-    setLibcallImpl(RTLIB::SINCOS_F128, RTLIB::sincos_f128);
-  }
-
-  setLibcallImpl(RTLIB::EXP10_F32, RTLIB::exp10f);
-  setLibcallImpl(RTLIB::EXP10_F64, RTLIB::exp10);
-  setLibcallImpl(RTLIB::EXP10_F128, RTLIB::exp10l_f128);
-
-  // These libcalls are only available in compiler-rt, not libgcc.
-  if (TT.isArch64Bit()) {
-    setLibcallImpl(RTLIB::SHL_I128, RTLIB::__ashlti3);
-    setLibcallImpl(RTLIB::SRL_I128, RTLIB::__lshrti3);
-    setLibcallImpl(RTLIB::SRA_I128, RTLIB::__ashrti3);
-    setLibcallImpl(RTLIB::MUL_I128, RTLIB::__multi3);
-    setLibcallImpl(RTLIB::MULO_I64, RTLIB::__mulodi4);
-  }
-
   if (TT.getArch() == Triple::ArchType::msp430) {
     setLibcallImplCallingConv(RTLIB::__mspabi_mpyll,
                               CallingConv::MSP430_BUILTIN);