[mlir][arith] Add support for min/max to ArithToAPFloat (#169760)

Add support for `arith.minnumf`, `arith.maxnumf`, `arith.minimumf`,
`arith.maximumf`.

Author: matthias-springer

mlir/lib/Conversion/ArithToAPFloat/ArithToAPFloat.cpp

@@ -513,6 +513,14 @@ void ArithToAPFloatConversionPass::runOnOperation() {
       context, "divide", getOperation());
   patterns.add<BinaryArithOpToAPFloatConversion<arith::RemFOp>>(
       context, "remainder", getOperation());
+  patterns.add<BinaryArithOpToAPFloatConversion<arith::MinNumFOp>>(
+      context, "minnum", getOperation());
+  patterns.add<BinaryArithOpToAPFloatConversion<arith::MaxNumFOp>>(
+      context, "maxnum", getOperation());
+  patterns.add<BinaryArithOpToAPFloatConversion<arith::MinimumFOp>>(
+      context, "minimum", getOperation());
+  patterns.add<BinaryArithOpToAPFloatConversion<arith::MaximumFOp>>(
+      context, "maximum", getOperation());
   patterns
       .add<FpToFpConversion<arith::ExtFOp>, FpToFpConversion<arith::TruncFOp>,
            CmpFOpToAPFloatConversion, NegFOpToAPFloatConversion>(

mlir/lib/ExecutionEngine/APFloatWrappers.cpp

@@ -151,4 +151,24 @@ MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_neg(int32_t semantics, uint6
   x.changeSign();
   return x.bitcastToAPInt().getZExtValue();
 }
+
+/// Min/max operations.
+#define APFLOAT_MIN_MAX_OP(OP)                                                 \
+  MLIR_APFLOAT_WRAPPERS_EXPORT uint64_t _mlir_apfloat_##OP(                    \
+      int32_t semantics, uint64_t a, uint64_t b) {                             \
+    const llvm::fltSemantics &sem = llvm::APFloatBase::EnumToSemantics(        \
+        static_cast<llvm::APFloatBase::Semantics>(semantics));                 \
+    unsigned bitWidth = llvm::APFloatBase::semanticsSizeInBits(sem);           \
+    llvm::APFloat lhs(sem, llvm::APInt(bitWidth, a));                          \
+    llvm::APFloat rhs(sem, llvm::APInt(bitWidth, b));                          \
+    llvm::APFloat result = llvm::OP(lhs, rhs);                                 \
+    return result.bitcastToAPInt().getZExtValue();                             \
+  }
+
+APFLOAT_MIN_MAX_OP(minimum)
+APFLOAT_MIN_MAX_OP(maximum)
+APFLOAT_MIN_MAX_OP(minnum)
+APFLOAT_MIN_MAX_OP(maxnum)
+
+#undef APFLOAT_MIN_MAX_OP
 }

mlir/test/Conversion/ArithToApfloat/arith-to-apfloat.mlir

@@ -223,3 +223,43 @@ func.func @negf(%arg0: f32) {
   %0 = arith.negf %arg0 : f32
   return
 }
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_minimum(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 2 : i32
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_minimum(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @minimumf(%arg0: f32, %arg1: f32) {
+  %0 = arith.minimumf %arg0, %arg1 : f32
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_maximum(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 2 : i32
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_maximum(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @maximumf(%arg0: f32, %arg1: f32) {
+  %0 = arith.maximumf %arg0, %arg1 : f32
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_minnum(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 2 : i32
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_minnum(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @minnumf(%arg0: f32, %arg1: f32) {
+  %0 = arith.minnumf %arg0, %arg1 : f32
+  return
+}
+
+// -----
+
+// CHECK: func.func private @_mlir_apfloat_maxnum(i32, i64, i64) -> i64
+// CHECK: %[[sem:.*]] = arith.constant 2 : i32
+// CHECK: %[[res:.*]] = call @_mlir_apfloat_maxnum(%[[sem]], %{{.*}}, %{{.*}}) : (i32, i64, i64) -> i64
+func.func @maxnumf(%arg0: f32, %arg1: f32) {
+  %0 = arith.maxnumf %arg0, %arg1 : f32
+  return
+}

mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation.mlir

@@ -47,6 +47,10 @@ func.func @entry() {
   %negated = arith.negf %cvt : f8E4M3FN
   vector.print %negated : f8E4M3FN
 
+  // CHECK-NEXT: -2.25
+  %min = arith.minimumf %cvt, %negated : f8E4M3FN
+  vector.print %min : f8E4M3FN
+
   // CHECK-NEXT: 1
   %cmp1 = arith.cmpf "olt", %cvt, %c1 : f8E4M3FN
   vector.print %cmp1 : i1