[llvm] [SelectionDAG][RISCV] Operations with static rounding (PR #100999)

[Serge Pavlov via llvm-commits]

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@@ -21427,6 +21432,23 @@ bool RISCVTargetLowering::preferScalarizeSplat(SDNode *N) const {
   return true;
 }
 
+int RISCVTargetLowering::getMachineRoundingMode(RoundingMode RM) const {
+  switch (RM) {
+  case RoundingMode::TowardZero:
+    return RISCVFPRndMode::RTZ;
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spavloff wrote:

It now is implemented using special node for RISCV, which differ from the target-neutral FADD_ROUND an other by using target dependent encoding. Selection DAG first builds target-neutral nodes, then they are loweded to RISCV-specific nodes, which in turn are lowered by TableGen patterns.

https://github.com/llvm/llvm-project/pull/100999