[llvm-branch-commits] [llvm] DAG: Fall back to separate sin and cos when softening sincos (PR #147468)

[Benjamin Maxwell via llvm-branch-commits]

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@@ -849,17 +849,46 @@ SDValue DAGTypeLegalizer::SoftenFloatRes_UnaryWithTwoFPResults(
     SetSoftenedFloat(SDValue(N, ResNum), CreateStackLoad(SlackSlot));
   }
 
-  return SDValue();
+  return true;
 }
 
 SDValue DAGTypeLegalizer::SoftenFloatRes_FSINCOS(SDNode *N) {
-  return SoftenFloatRes_UnaryWithTwoFPResults(
-      N, RTLIB::getSINCOS(N->getValueType(0)));
+  EVT VT = N->getValueType(0);
+  if (SoftenFloatRes_UnaryWithTwoFPResults(N, RTLIB::getSINCOS(VT)))
+    return SDValue();
+
+  // Fall back on softening the separate sin and cos calls if available.
+  RTLIB::Libcall SinLC = RTLIB::getSIN(VT);
+  RTLIB::Libcall CosLC = RTLIB::getCOS(VT);
+
+  SDValue SoftSin, SoftCos;
+  if (!TLI.getLibcallName(SinLC) || !TLI.getLibcallName(CosLC)) {
+    DAG.getContext()->emitError("do not know how to soften fsincos");
+
+    EVT NVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
+    SoftSin = SoftCos = DAG.getPOISON(NVT);
+  } else {
+    SoftSin = SoftenFloatRes_Unary(N, SinLC);
+    SoftCos = SoftenFloatRes_Unary(N, CosLC);
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MacDue wrote:

This seems off as `SoftenFloatRes_Unary` expects a single-result node, but I think here it's fine (looks like it wouldn't work for strict nodes though). 

https://github.com/llvm/llvm-project/pull/147468