[Mlir-commits] [mlir] Introduce `arith.scaling_extf` and `arith.scaling_truncf` (PR #141965)

[Umang Yadav]

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@@ -409,6 +421,125 @@ struct F8E8M0TruncFOpConverter : public OpRewritePattern<arith::TruncFOp> {
   }
 };
 
+struct ScalingExtFOpConverter : public OpRewritePattern<arith::ScalingExtFOp> {
+  using OpRewritePattern::OpRewritePattern;
+  LogicalResult matchAndRewrite(arith::ScalingExtFOp op,
+                                PatternRewriter &rewriter) const final {
+    ImplicitLocOpBuilder b(op.getLoc(), rewriter);
+    Value inputOperand = op.getIn();
+    Value scaleOperand = op.getScale();
+    Type scaleETy = getElementTypeOrSelf(scaleOperand);
+    // allow implicit exponent extraction from 16/32 bits floats
+    if (scaleETy.getIntOrFloatBitWidth() >= 16) {
+      scaleETy = b.getF8E8M0Type();
+      scaleOperand = b.create<arith::TruncFOp>(scaleETy, scaleOperand);
+    }
+    if (!llvm::isa<Float8E8M0FNUType>(scaleETy)) {
+      return rewriter.notifyMatchFailure(
+          op, "scaling extf is not using scale operand of type f8E8M0FNU");
+    }
+    Type resultTy = op.getType();
+    // extf on scale will essentially create f32 number that is 2^scale and will
----------------
umangyadav wrote:

> why f32? can't resultTy be any float type
Changed comment to better reflect what it's doing. 

> should we check if resultTy >= Float8E8M0FNU and >= inputType

As part of verification, it checks that output dtype is of larger widhth compared to input.
https://github.com/umangyadav/llvm-project/blob/d1543414578abf95a495b4eb6fe9b6201de8e9f6/mlir/lib/Dialect/Arith/IR/ArithOps.cpp#L1460



https://github.com/llvm/llvm-project/pull/141965