[mlir][emitc] Support convert arith.extf and arith.truncf to emitc (#121184)

mlir/lib/Conversion/ArithToEmitC/ArithToEmitC.cpp

@@ -733,6 +733,43 @@ public:
   }
 };
 
+// Floating-point to floating-point conversions.
+template <typename CastOp>
+class FpCastOpConversion : public OpConversionPattern<CastOp> {
+public:
+  FpCastOpConversion(const TypeConverter &typeConverter, MLIRContext *context)
+      : OpConversionPattern<CastOp>(typeConverter, context) {}
+
+  LogicalResult
+  matchAndRewrite(CastOp castOp, typename CastOp::Adaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    // Vectors in particular are not supported.
+    Type operandType = adaptor.getIn().getType();
+    if (!emitc::isSupportedFloatType(operandType))
+      return rewriter.notifyMatchFailure(castOp,
+                                         "unsupported cast source type");
+    if (auto roundingModeOp =
+            dyn_cast<arith::ArithRoundingModeInterface>(*castOp)) {
+      // Only supporting default rounding mode as of now.
+      if (roundingModeOp.getRoundingModeAttr())
+        return rewriter.notifyMatchFailure(castOp, "unsupported rounding mode");
+    }
+
+    Type dstType = this->getTypeConverter()->convertType(castOp.getType());
+    if (!dstType)
+      return rewriter.notifyMatchFailure(castOp, "type conversion failed");
+
+    if (!emitc::isSupportedFloatType(dstType))
+      return rewriter.notifyMatchFailure(castOp,
+                                         "unsupported cast destination type");
+
+    Value fpCastOperand = adaptor.getIn();
+    rewriter.replaceOpWithNewOp<emitc::CastOp>(castOp, dstType, fpCastOperand);
+
+    return success();
+  }
+};
+
 } // namespace
 
 //===----------------------------------------------------------------------===//
@@ -778,7 +815,9 @@ void mlir::populateArithToEmitCPatterns(TypeConverter &typeConverter,
     ItoFCastOpConversion<arith::SIToFPOp>,
     ItoFCastOpConversion<arith::UIToFPOp>,
     FtoICastOpConversion<arith::FPToSIOp>,
-    FtoICastOpConversion<arith::FPToUIOp>
+    FtoICastOpConversion<arith::FPToUIOp>,
+    FpCastOpConversion<arith::ExtFOp>,
+    FpCastOpConversion<arith::TruncFOp>
   >(typeConverter, ctx);
   // clang-format on
 }

mlir/test/Conversion/ArithToEmitC/arith-to-emitc-unsupported.mlir

@@ -149,3 +149,43 @@ func.func @arith_remui_vector(%arg0: vector<5xi32>, %arg1: vector<5xi32>) -> vec
   %divui = arith.remui %arg0, %arg1 : vector<5xi32>
   return %divui: vector<5xi32>
 }
+
+// -----
+
+func.func @arith_truncf(%arg0: f64) -> f32 {
+  // expected-error @+1 {{failed to legalize operation 'arith.truncf'}}
+  %truncd = arith.truncf %arg0 to_nearest_away : f64 to f32
+  return %truncd : f32
+}
+
+// -----
+
+func.func @arith_extf_f128(%arg0: f32) -> f128 {
+  // expected-error @+1 {{failed to legalize operation 'arith.extf'}}
+  %extd = arith.extf %arg0 : f32 to f128
+  return %extd : f128
+}
+
+// -----
+
+func.func @arith_truncf_f128(%arg0: f128) -> f32 {
+  // expected-error @+1 {{failed to legalize operation 'arith.truncf'}}
+  %truncd = arith.truncf %arg0 : f128 to f32
+  return %truncd : f32
+}
+
+// -----
+
+func.func @arith_extf_vector(%arg0: vector<4xf32>) -> vector<4xf64> {
+  // expected-error @+1 {{failed to legalize operation 'arith.extf'}}
+  %extd = arith.extf %arg0 : vector<4xf32> to vector<4xf64>
+  return %extd : vector<4xf64>
+}
+
+// -----
+
+func.func @arith_truncf_vector(%arg0: vector<4xf64>) -> vector<4xf32> {
+  // expected-error @+1 {{failed to legalize operation 'arith.truncf'}}
+  %truncd = arith.truncf %arg0 : vector<4xf64> to vector<4xf32>
+  return %truncd : vector<4xf32>
+}

mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir

@@ -739,3 +739,29 @@ func.func @arith_divui_remui(%arg0: i32, %arg1: i32) -> i32 {
 
   return %div : i32
 }
+
+// -----
+
+func.func @arith_extf(%arg0: f16) -> f64 {
+  // CHECK-LABEL: arith_extf
+  // CHECK-SAME: (%[[Arg0:[^ ]*]]: f16)
+  // CHECK: %[[Extd0:.*]] = emitc.cast %[[Arg0]] : f16 to f32
+  %extd0 = arith.extf %arg0 : f16 to f32
+  // CHECK: %[[Extd1:.*]] = emitc.cast %[[Extd0]] : f32 to f64
+  %extd1 = arith.extf %extd0 : f32 to f64
+
+  return %extd1 : f64
+}
+
+// -----
+
+func.func @arith_truncf(%arg0: f64) -> f16 {
+  // CHECK-LABEL: arith_truncf
+  // CHECK-SAME: (%[[Arg0:[^ ]*]]: f64)
+  // CHECK: %[[Truncd0:.*]] = emitc.cast %[[Arg0]] : f64 to f32
+  %truncd0 = arith.truncf %arg0 : f64 to f32
+  // CHECK: %[[Truncd1:.*]] = emitc.cast %[[Truncd0]] : f32 to f16
+  %truncd1 = arith.truncf %truncd0 : f32 to f16
+
+  return %truncd1 : f16
+}