[flang][OpenMP] Use maxnum/minnum for lowering of max/min reduction operators (#89258)

This patch changes the lowering of max and min to be lowered to
arith::MaxNumFop and arith::MinNumFOp instead of using arith::MaximumFOp
and arith::MinimumFOp. The arith::MaximumFOp and arith::MinimumFOp map
to the corresponding intrinsics llvm.maximum.* and llvm.minimum.*
intrinsics which conform to the semantics specified in the draft of IEEE
754-2019, which is not supported by all hardware. Instead using
arith::MaximumFOp and arith::MinimumFOp will allow code generation for
more targets and match the code generated by clang OpenMP.

fixes #87955

Author: jsjodin

flang/lib/Lower/OpenMP/ReductionProcessor.cpp

@@ -220,12 +220,12 @@ mlir::Value ReductionProcessor::createScalarCombiner(
   switch (redId) {
   case ReductionIdentifier::MAX:
     reductionOp =
-        getReductionOperation<mlir::arith::MaximumFOp, mlir::arith::MaxSIOp>(
+        getReductionOperation<mlir::arith::MaxNumFOp, mlir::arith::MaxSIOp>(
             builder, type, loc, op1, op2);
     break;
   case ReductionIdentifier::MIN:
     reductionOp =
-        getReductionOperation<mlir::arith::MinimumFOp, mlir::arith::MinSIOp>(
+        getReductionOperation<mlir::arith::MinNumFOp, mlir::arith::MinSIOp>(
             builder, type, loc, op1, op2);
     break;
   case ReductionIdentifier::IOR:

flang/test/Lower/OpenMP/FIR/wsloop-reduction-max-byref.f90

@@ -11,7 +11,7 @@
 !CHECK: ^bb0(%[[ARG0:.*]]: !fir.ref<f32>, %[[ARG1:.*]]: !fir.ref<f32>):
 !CHECK:   %[[LD0:.*]] = fir.load %[[ARG0]] : !fir.ref<f32>
 !CHECK:   %[[LD1:.*]] = fir.load %[[ARG1]] : !fir.ref<f32>
-!CHECK:   %[[RES:.*]] = arith.maximumf %[[LD0]], %[[LD1]] {{.*}}: f32
+!CHECK:   %[[RES:.*]] = arith.maxnumf %[[LD0]], %[[LD1]] {{.*}}: f32
 !CHECK:   fir.store %[[RES]] to %[[ARG0]] : !fir.ref<f32>
 !CHECK:   omp.yield(%[[ARG0]] : !fir.ref<f32>)
 

flang/test/Lower/OpenMP/FIR/wsloop-reduction-max.f90

@@ -6,7 +6,7 @@
 !CHECK:   omp.yield(%[[MINIMUM_VAL_F]] : f32)
 !CHECK: combiner
 !CHECK: ^bb0(%[[ARG0_F:.*]]: f32, %[[ARG1_F:.*]]: f32):
-!CHECK:   %[[COMB_VAL_F:.*]] = arith.maximumf %[[ARG0_F]], %[[ARG1_F]] {{.*}}: f32
+!CHECK:   %[[COMB_VAL_F:.*]] = arith.maxnumf %[[ARG0_F]], %[[ARG1_F]] {{.*}}: f32
 !CHECK:   omp.yield(%[[COMB_VAL_F]] : f32)
 
 !CHECK: omp.declare_reduction @[[MAX_DECLARE_I:.*]] : i32 init {

flang/test/Lower/OpenMP/FIR/wsloop-reduction-min-byref.f90

@@ -11,7 +11,7 @@
 !CHECK: ^bb0(%[[ARG0:.*]]: !fir.ref<f32>, %[[ARG1:.*]]: !fir.ref<f32>):
 !CHECK:   %[[LD0:.*]] = fir.load %[[ARG0]] : !fir.ref<f32>
 !CHECK:   %[[LD1:.*]] = fir.load %[[ARG1]] : !fir.ref<f32>
-!CHECK:   %[[RES:.*]] = arith.minimumf %[[LD0]], %[[LD1]] {{.*}}: f32
+!CHECK:   %[[RES:.*]] = arith.minnumf %[[LD0]], %[[LD1]] {{.*}}: f32
 !CHECK:   fir.store %[[RES]] to %[[ARG0]] : !fir.ref<f32>
 !CHECK:   omp.yield(%[[ARG0]] : !fir.ref<f32>)
 

flang/test/Lower/OpenMP/FIR/wsloop-reduction-min.f90

@@ -6,7 +6,7 @@
 !CHECK:   omp.yield(%[[MAXIMUM_VAL_F]] : f32)
 !CHECK: combiner
 !CHECK: ^bb0(%[[ARG0_F:.*]]: f32, %[[ARG1_F:.*]]: f32):
-!CHECK:   %[[COMB_VAL_F:.*]] = arith.minimumf %[[ARG0_F]], %[[ARG1_F]] {{.*}}: f32
+!CHECK:   %[[COMB_VAL_F:.*]] = arith.minnumf %[[ARG0_F]], %[[ARG1_F]] {{.*}}: f32
 !CHECK:   omp.yield(%[[COMB_VAL_F]] : f32)
 
 !CHECK: omp.declare_reduction @[[MIN_DECLARE_I:.*]] : i32 init {

flang/test/Lower/OpenMP/wsloop-reduction-max-byref.f90

@@ -13,7 +13,7 @@
 !CHECK: ^bb0(%[[ARG0:.*]]: !fir.ref<f32>, %[[ARG1:.*]]: !fir.ref<f32>):
 !CHECK:   %[[LD0:.*]] = fir.load %[[ARG0]] : !fir.ref<f32>
 !CHECK:   %[[LD1:.*]] = fir.load %[[ARG1]] : !fir.ref<f32>
-!CHECK:   %[[RES:.*]] = arith.maximumf %[[LD0]], %[[LD1]] {{.*}}: f32
+!CHECK:   %[[RES:.*]] = arith.maxnumf %[[LD0]], %[[LD1]] {{.*}}: f32
 !CHECK:   fir.store %[[RES]] to %[[ARG0]] : !fir.ref<f32>
 !CHECK:   omp.yield(%[[ARG0]] : !fir.ref<f32>)
 

flang/test/Lower/OpenMP/wsloop-reduction-max.f90

@@ -10,7 +10,7 @@
 
 ! CHECK-LABEL:   } combiner {
 ! CHECK:         ^bb0(%[[VAL_0:.*]]: f32, %[[VAL_1:.*]]: f32):
-! CHECK:           %[[VAL_2:.*]] = arith.maximumf %[[VAL_0]], %[[VAL_1]] fastmath<contract> : f32
+! CHECK:           %[[VAL_2:.*]] = arith.maxnumf %[[VAL_0]], %[[VAL_1]] fastmath<contract> : f32
 ! CHECK:           omp.yield(%[[VAL_2]] : f32)
 ! CHECK:         }
 

flang/test/Lower/OpenMP/wsloop-reduction-min-byref.f90

@@ -13,7 +13,7 @@
 !CHECK: ^bb0(%[[ARG0:.*]]: !fir.ref<f32>, %[[ARG1:.*]]: !fir.ref<f32>):
 !CHECK:   %[[LD0:.*]] = fir.load %[[ARG0]] : !fir.ref<f32>
 !CHECK:   %[[LD1:.*]] = fir.load %[[ARG1]] : !fir.ref<f32>
-!CHECK:   %[[RES:.*]] = arith.minimumf %[[LD0]], %[[LD1]] {{.*}}: f32
+!CHECK:   %[[RES:.*]] = arith.minnumf %[[LD0]], %[[LD1]] {{.*}}: f32
 !CHECK:   fir.store %[[RES]] to %[[ARG0]] : !fir.ref<f32>
 !CHECK:   omp.yield(%[[ARG0]] : !fir.ref<f32>)
 

flang/test/Lower/OpenMP/wsloop-reduction-min.f90

@@ -10,7 +10,7 @@
 
 ! CHECK-LABEL:   } combiner {
 ! CHECK:         ^bb0(%[[VAL_0:.*]]: f32, %[[VAL_1:.*]]: f32):
-! CHECK:           %[[VAL_2:.*]] = arith.minimumf %[[VAL_0]], %[[VAL_1]] fastmath<contract> : f32
+! CHECK:           %[[VAL_2:.*]] = arith.minnumf %[[VAL_0]], %[[VAL_1]] fastmath<contract> : f32
 ! CHECK:           omp.yield(%[[VAL_2]] : f32)
 ! CHECK:         }