[Mlir-commits] [mlir] [mlir][SPIR-V] Fix math.powf lowering for non-integer exponents (PR #197727)

[Igor Wodiany]

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@@ -360,75 +362,86 @@ struct PowFOpPattern final : public OpConversionPattern<math::PowFOp> {
     if (!dstType)
       return failure();
 
-    // Get the scalar float type.
-    FloatType scalarFloatType;
-    if (auto scalarType = dyn_cast<FloatType>(powfOp.getType())) {
-      scalarFloatType = scalarType;
-    } else if (auto vectorType = dyn_cast<VectorType>(powfOp.getType())) {
-      scalarFloatType = cast<FloatType>(vectorType.getElementType());
-    } else {
-      return failure();
+    Location loc = powfOp.getLoc();
+    auto operandType = adaptor.getRhs().getType();
+
+    // Parity-based lowering requires an integer-valued constant exponent.
+    // Otherwise fall back to exp(y*log(x)), which yields NaN for x<0 (matches
+    // C).
+    auto isOdd = [](const APFloat &v) {
+      APSInt i(/*BitWidth=*/64, /*isUnsigned=*/false);
+      bool ignored;
+      v.convertToInteger(i, APFloat::rmTowardZero, &ignored);
+      return i[0];
+    };
+
+    Attribute rhsAttr;
+    SmallVector<bool> oddMask;
+    bool isIntegerValued = false;
+    if (matchPattern(adaptor.getRhs(), m_Constant(&rhsAttr))) {
+      isIntegerValued = TypeSwitch<Attribute, bool>(rhsAttr)
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IgWod wrote:

Can we make the formatting less ugly somehow? If absolutely necessary you can wrap it in `// clang-format off` and `// clang-format on`. 

https://github.com/llvm/llvm-project/pull/197727