[SelectionDAG] Only lower COPYSIGN_PPC_F128 to copysignl

This reduces the burden on frontends that wish to support float ops
without needing a C compiler to build LLVM's compiler-rt for that target,
e.g. so that they can be a fully self-contained toolchain for bare-metal.

All other floats are expanded for all current architectures just fine.
PowerPC, however, does not efficiently legalize its very own float.

Author: workingjubilee

llvm/include/llvm/IR/RuntimeLibcalls.def

@@ -289,10 +289,6 @@ HANDLE_LIBCALL(FLOOR_F64, "floor")
 HANDLE_LIBCALL(FLOOR_F80, "floorl")
 HANDLE_LIBCALL(FLOOR_F128, "floorl")
 HANDLE_LIBCALL(FLOOR_PPCF128, "floorl")
-HANDLE_LIBCALL(COPYSIGN_F32, "copysignf")
-HANDLE_LIBCALL(COPYSIGN_F64, "copysign")
-HANDLE_LIBCALL(COPYSIGN_F80, "copysignl")
-HANDLE_LIBCALL(COPYSIGN_F128, "copysignl")
 HANDLE_LIBCALL(COPYSIGN_PPCF128, "copysignl")
 HANDLE_LIBCALL(FMIN_F32, "fminf")
 HANDLE_LIBCALL(FMIN_F64, "fmin")

llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp

@@ -1709,12 +1709,12 @@ void DAGTypeLegalizer::ExpandFloatRes_FCEIL(SDNode *N,
 
 void DAGTypeLegalizer::ExpandFloatRes_FCOPYSIGN(SDNode *N,
                                                 SDValue &Lo, SDValue &Hi) {
-  ExpandFloatRes_Binary(N, GetFPLibCall(N->getValueType(0),
-                                        RTLIB::COPYSIGN_F32,
-                                        RTLIB::COPYSIGN_F64,
-                                        RTLIB::COPYSIGN_F80,
-                                        RTLIB::COPYSIGN_F128,
-                                        RTLIB::COPYSIGN_PPCF128), Lo, Hi);
+
+  EVT VT = N->getValueType(0);
+  ExpandFloatRes_Binary(
+      N,
+      (VT == MVT::ppcf128 ? RTLIB::COPYSIGN_PPCF128 : RTLIB::UNKNOWN_LIBCALL),
+      Lo, Hi);
 }
 
 void DAGTypeLegalizer::ExpandFloatRes_FCOS(SDNode *N,

llvm/lib/IR/RuntimeLibcalls.cpp

@@ -62,7 +62,6 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT) {
     setLibcallName(RTLIB::ROUND_F128, "roundf128");
     setLibcallName(RTLIB::ROUNDEVEN_F128, "roundevenf128");
     setLibcallName(RTLIB::FLOOR_F128, "floorf128");
-    setLibcallName(RTLIB::COPYSIGN_F128, "copysignf128");
     setLibcallName(RTLIB::FMIN_F128, "fminf128");
     setLibcallName(RTLIB::FMAX_F128, "fmaxf128");
     setLibcallName(RTLIB::LROUND_F128, "lroundf128");

llvm/lib/Target/SystemZ/ZOSLibcallNames.def

@@ -87,9 +87,6 @@ HANDLE_LIBCALL(EXP2_F128, "@@LXP2@B")
 HANDLE_LIBCALL(COS_F64, "@@SCOS@B")
 HANDLE_LIBCALL(COS_F32, "@@FCOS@B")
 HANDLE_LIBCALL(COS_F128, "@@LCOS@B")
-HANDLE_LIBCALL(COPYSIGN_F64, "@@DCPY@B")
-HANDLE_LIBCALL(COPYSIGN_F32, "@@FCPY@B")
-HANDLE_LIBCALL(COPYSIGN_F128, "@@LCPY@B")
 HANDLE_LIBCALL(CEIL_F64, "@@SCEL@B")
 HANDLE_LIBCALL(CEIL_F32, "@@FCEL@B")
 HANDLE_LIBCALL(CEIL_F128, "@@LCEL@B")

llvm/lib/Target/WebAssembly/WebAssemblyRuntimeLibcallSignatures.cpp

@@ -264,9 +264,6 @@ struct RuntimeLibcallSignatureTable {
     Table[RTLIB::FLOOR_F32] = f32_func_f32;
     Table[RTLIB::FLOOR_F64] = f64_func_f64;
     Table[RTLIB::FLOOR_F128] = i64_i64_func_i64_i64;
-    Table[RTLIB::COPYSIGN_F32] = f32_func_f32_f32;
-    Table[RTLIB::COPYSIGN_F64] = f64_func_f64_f64;
-    Table[RTLIB::COPYSIGN_F128] = i64_i64_func_i64_i64_i64_i64;
     Table[RTLIB::FMIN_F32] = f32_func_f32_f32;
     Table[RTLIB::FMIN_F64] = f64_func_f64_f64;
     Table[RTLIB::FMIN_F128] = i64_i64_func_i64_i64_i64_i64;