[flang] Lower scalar negation

[clementval]

Summary

Handle negation on scalar expression.

res = -a

This patch is part of the upstreaming effort from fir-dev branch.

Co-authored-by: Jean Perier <[e-mail]>
Co-authored-by: Eric Schweitz <[e-mail]>

[PeteSteinfeld]

All builds and tests correctly and looks good.

flang/lib/Lower/ConvertExpr.cpp

public:
   template <int KIND>
   ExtValue genval(const Fortran::evaluate::ComplexComponent<KIND> &part) {
     TODO(getLoc(), "genval ComplexComponent");
   }
 
   template <int KIND>
   ExtValue genval(const Fortran::evaluate::Negate<Fortran::evaluate::Type<
                       Fortran::common::TypeCategory::Integer, KIND>> &op) {
-    TODO(getLoc(), "genval Negate integer");
+    mlir::Value input = genunbox(op.left());
+    // Like LLVM, integer negation is the binary op "0 - value"
+    mlir::Value zero = genIntegerConstant<KIND>(builder.getContext(), 0);
+    return builder.create<mlir::arith::SubIOp>(getLoc(), zero, input);
   }
 
   template <int KIND>
   ExtValue genval(const Fortran::evaluate::Negate<Fortran::evaluate::Type<
                       Fortran::common::TypeCategory::Real, KIND>> &op) {
-    TODO(getLoc(), "genval Negate real");
+    return builder.create<mlir::arith::NegFOp>(getLoc(), genunbox(op.left()));
   }
   template <int KIND>
   ExtValue genval(const Fortran::evaluate::Negate<Fortran::evaluate::Type<
                       Fortran::common::TypeCategory::Complex, KIND>> &op) {
-    TODO(getLoc(), "genval Negate complex");
+    return builder.create<fir::NegcOp>(getLoc(), genunbox(op.left()));
   }
 
 #undef GENBIN
 #define GENBIN(GenBinEvOp, GenBinTyCat, GenBinFirOp)                           \
   template <int KIND>                                                          \
   ExtValue genval(const Fortran::evaluate::GenBinEvOp<Fortran::evaluate::Type< \
                       Fortran::common::TypeCategory::GenBinTyCat, KIND>> &x) { \
     TODO(getLoc(), "genval GenBinEvOp");                                       \

flang/test/Lower/assignment.f90

 end
 
 ! CHECK-LABEL: func @_QPsub2(
 ! CHECK:         %[[A:.*]]: !fir.ref<i32> {fir.bindc_name = "a"}
 ! CHECK:         %[[B:.*]]: !fir.ref<i64> {fir.bindc_name = "b"}
 ! CHECK:         %[[B_VAL:.*]] = fir.load %arg1 : !fir.ref<i64>
 ! CHECK:         %[[B_CONV:.*]] = fir.convert %[[B_VAL]] : (i64) -> i32
 ! CHECK:         fir.store %[[B_CONV]] to %[[A]] : !fir.ref<i32>
+
+integer function negi(a)
+  integer :: a
+  negi = -a
+end 
+
+! CHECK-LABEL: func @_QPnegi(
+! CHECK-SAME:    %[[A:.*]]: !fir.ref<i32> {fir.bindc_name = "a"}) -> i32 {
+! CHECK:         %[[FCTRES:.*]] = fir.alloca i32 {bindc_name = "negi", uniq_name = "_QFnegiEnegi"}
+! CHECK:         %[[A_VAL:.*]] = fir.load %[[A]] : !fir.ref<i32>
+! CHECK:         %[[C0:.*]] = arith.constant 0 : i32
+! CHECK:         %[[NEG:.*]] = arith.subi %[[C0]], %[[A_VAL]] : i32
+! CHECK:         fir.store %[[NEG]] to %[[FCTRES]] : !fir.ref<i32>
+! CHECK:         %[[RET:.*]] = fir.load %[[FCTRES]] : !fir.ref<i32>
+! CHECK:         return %[[RET]] : i32
+
+real function negr(a)
+  real :: a
+  negr = -a
+end 
+
+! CHECK-LABEL: func @_QPnegr(
+! CHECK-SAME:    %[[A:.*]]: !fir.ref<f32> {fir.bindc_name = "a"}) -> f32 {
+! CHECK:         %[[FCTRES:.*]] = fir.alloca f32 {bindc_name = "negr", uniq_name = "_QFnegrEnegr"}
+! CHECK:         %[[A_VAL:.*]] = fir.load %[[A]] : !fir.ref<f32>
+! CHECK:         %[[NEG:.*]] = arith.negf %[[A_VAL]] : f32
+! CHECK:         fir.store %[[NEG]] to %[[FCTRES]] : !fir.ref<f32>
+! CHECK:         %[[RET:.*]] = fir.load %[[FCTRES]] : !fir.ref<f32>
+! CHECK:         return %[[RET]] : f32
+
+complex function negc(a)
+  complex :: a
+  negc = -a
+end 
+
+! CHECK-LABEL: func @_QPnegc(
+! CHECK-SAME:    %[[A:.*]]: !fir.ref<!fir.complex<4>> {fir.bindc_name = "a"}) -> !fir.complex<4> {
+! CHECK:         %[[FCTRES:.*]] = fir.alloca !fir.complex<4> {bindc_name = "negc", uniq_name = "_QFnegcEnegc"}
+! CHECK:         %[[A_VAL:.*]] = fir.load %[[A]] : !fir.ref<!fir.complex<4>>
+! CHECK:         %[[NEG:.*]] = fir.negc %[[A_VAL]] : !fir.complex<4>
+! CHECK:         fir.store %[[NEG]] to %[[FCTRES]] : !fir.ref<!fir.complex<4>>
+! CHECK:         %[[RET:.*]] = fir.load %[[FCTRES]] : !fir.ref<!fir.complex<4>>
+! CHECK:         return %[[RET]] : !fir.complex<4>