[llvm] BasicTTI: Cleanup multiple result intrinsic handling (PR #165970)

[Matt Arsenault via llvm-commits]

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@@ -311,12 +310,45 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
         !isVectorizedStructTy(cast<StructType>(RetTy)))
       return std::nullopt;
 
+    Type *Ty = getContainedTypes(RetTy).front();
+    EVT VT = getTLI()->getValueType(DL, Ty);
+
+    EVT ScalarVT = VT.getScalarType();
+    RTLIB::Libcall LC = RTLIB::UNKNOWN_LIBCALL;
+
+    switch (ICA.getID()) {
+    case Intrinsic::modf:
+      LC = RTLIB::getMODF(ScalarVT);
+      break;
+    case Intrinsic::sincospi:
+      LC = RTLIB::getSINCOSPI(ScalarVT);
+      break;
+    case Intrinsic::sincos:
+      // TODO: Account for sincos_stret not always using a memory operation for
+      // the out argument
+      LC = RTLIB::getSINCOS_STRET(ScalarVT);
+
+      if (getTLI()->getLibcallImpl(LC) == RTLIB::Unsupported)
+        LC = RTLIB::getSINCOS(ScalarVT);
+
+      break;
+    default:
+      return std::nullopt;
+    }
+
     // Find associated libcall.
-    const char *LCName = getTLI()->getLibcallName(LC);
-    if (!LCName)
+    RTLIB::LibcallImpl LibcallImpl = getTLI()->getLibcallImpl(LC);
+    if (LibcallImpl == RTLIB::Unsupported)
       return std::nullopt;
 
+    StringRef LCName =
+        RTLIB::RuntimeLibcallsInfo::getLibcallImplName(LibcallImpl);
+
     // Search for a corresponding vector variant.
+    //
+    // FIXME: CodeGen use RuntimeLibcallsInfo, not TargetLibraryInfo and has no
+    // path to using the vector libcalls. So this guess at how legalization will
+    // work is just wrong.
----------------
arsenm wrote:

Hmm, I found it. This is basically a special case system and no other intrinsic is handled this way. We should have entries in RuntimeLibcalls like we do for all the scalar types, rather than having a side mechanism (e.g., as it is now the vector libcalls will not be retained in full LTO which will later be necessary) 

https://github.com/llvm/llvm-project/pull/165970