[Flang] Lower the trim intrinsic

The trim intrinsic removes trailing blank spaces from a string. The
intrinsic is lowered to a runtime call.

This is part of the upstreaming effort from the fir-dev branch in [1].
[1] https://github.com/flang-compiler/f18-llvm-project

Reviewed By: jeanPerier

Differential Revision: https://reviews.llvm.org/D121901

Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Valentin Clement <clementval@gmail.com>
Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>

flang/lib/Lower/IntrinsicCall.cpp

@@ -505,6 +505,7 @@ struct IntrinsicLibrary {
   void genSystemClock(llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genTransfer(mlir::Type,
                                  llvm::ArrayRef<fir::ExtendedValue>);
+  fir::ExtendedValue genTrim(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genUbound(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genUnpack(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genVerify(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
@@ -804,6 +805,7 @@ static constexpr IntrinsicHandler handlers[]{
      &I::genTransfer,
      {{{"source", asAddr}, {"mold", asAddr}, {"size", asValue}}},
      /*isElemental=*/false},
+    {"trim", &I::genTrim, {{{"string", asAddr}}}, /*isElemental=*/false},
     {"ubound",
      &I::genUbound,
      {{{"array", asBox}, {"dim", asValue}, {"kind", asValue}}},
@@ -3061,6 +3063,23 @@ IntrinsicLibrary::genUbound(mlir::Type resultType,
   return mlir::Value();
 }
 
+// TRIM
+fir::ExtendedValue
+IntrinsicLibrary::genTrim(mlir::Type resultType,
+                          llvm::ArrayRef<fir::ExtendedValue> args) {
+  assert(args.size() == 1);
+  mlir::Value string = builder.createBox(loc, args[0]);
+  // Create mutable fir.box to be passed to the runtime for the result.
+  fir::MutableBoxValue resultMutableBox =
+      fir::factory::createTempMutableBox(builder, loc, resultType);
+  mlir::Value resultIrBox =
+      fir::factory::getMutableIRBox(builder, loc, resultMutableBox);
+  // Call runtime. The runtime is allocating the result.
+  fir::runtime::genTrim(builder, loc, resultIrBox, string);
+  // Read result from mutable fir.box and add it to the list of temps to be
+  // finalized by the StatementContext.
+  return readAndAddCleanUp(resultMutableBox, resultType, "TRIM");
+}
 // UNPACK
 fir::ExtendedValue
 IntrinsicLibrary::genUnpack(mlir::Type resultType,

flang/test/Lower/Intrinsics/trim.f90

@@ -0,0 +1,21 @@
+! RUN: bbc -emit-fir %s -o - | FileCheck %s
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck %s
+
+! CHECK-LABEL: func @_QPtrim_test(
+! CHECK-SAME: %[[arg0:.*]]: !fir.boxchar<1>{{.*}}) {
+subroutine trim_test(c)
+  character(*) :: c
+  ! CHECK: %[[tmpBox:.*]] = fir.alloca !fir.box<!fir.heap<!fir.char<1,?>>>
+  ! CHECK-DAG: %[[c:.*]]:2 = fir.unboxchar %[[arg0]] : (!fir.boxchar<1>) -> (!fir.ref<!fir.char<1,?>>, index)
+  ! CHECK-DAG: %[[cBox:.*]] = fir.embox %[[c]]#0 typeparams %[[c]]#1 : (!fir.ref<!fir.char<1,?>>, index) -> !fir.box<!fir.char<1,?>>
+  ! CHECK-DAG: %[[cBoxNone:.*]] = fir.convert %[[cBox]] : (!fir.box<!fir.char<1,?>>) -> !fir.box<none>
+  ! CHECK-DAG: %[[resBox:.*]] = fir.convert %[[tmpBox]] : (!fir.ref<!fir.box<!fir.heap<!fir.char<1,?>>>>) -> !fir.ref<!fir.box<none>>
+  ! CHECK: fir.call @{{.*}}Trim(%[[resBox]], %[[cBoxNone]], {{.*}}) : (!fir.ref<!fir.box<none>>, !fir.box<none>, !fir.ref<i8>, i32) -> none
+  ! CHECK-DAG: %[[tmpAddr:.*]] = fir.box_addr
+  ! CHECK-DAG: fir.box_elesize
+  ! CHECK: fir.call @{{.*}}bar_trim_test
+  call bar_trim_test(trim(c))
+  ! CHECK: fir.freemem %[[tmpAddr]] : <!fir.char<1,?>>
+  return
+end subroutine
+