[Mlir-commits] [mlir] [mlir][arith][spirv] Convert arith.truncf rounding mode to SPIR-V (PR #101547)

[Jakub Kuderski]

================
@@ -807,6 +807,25 @@ struct TruncIPattern final : public OpConversionPattern<arith::TruncIOp> {
 // TypeCastingOp
 //===----------------------------------------------------------------------===//
 
+static std::optional<spirv::FPRoundingMode>
+convertArithRoundingModeToSPIRV(arith::RoundingMode roundingMode) {
+  switch (roundingMode) {
+  case arith::RoundingMode::downward:
+    return spirv::FPRoundingMode::RTN;
+  case arith::RoundingMode::to_nearest_even:
+    return spirv::FPRoundingMode::RTE;
+  case arith::RoundingMode::toward_zero:
+    return spirv::FPRoundingMode::RTZ;
+  case arith::RoundingMode::upward:
+    return spirv::FPRoundingMode::RTP;
+  case arith::RoundingMode::to_nearest_away:
+    // SPIR-V FPRoundingMode decoration has no ties-away-from-zero mode
+    // (as of SPIR-V 1.6)
+    return {};
----------------
kuhar wrote:

```suggestion
    return std::nullopt;
```

https://github.com/llvm/llvm-project/pull/101547