[Flang] Lower the trim intrinsic

[kiranchandramohan]

Summary

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

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

[jeanPerier]

LGTM

flang/lib/Lower/IntrinsicCall.cpp

struct IntrinsicLibrary {
   mlir::Value genSetExponent(mlir::Type resultType,
                              llvm::ArrayRef<mlir::Value> args);
   fir::ExtendedValue genSize(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genSum(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genSpread(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   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>);
 
   /// Define the different FIR generators that can be mapped to intrinsic to
   /// generate the related code.
   using ElementalGenerator = decltype(&IntrinsicLibrary::genAbs);
   using ExtendedGenerator = decltype(&IntrinsicLibrary::genSum);
static constexpr IntrinsicHandler handlers[]{
     {"system_clock",
      &I::genSystemClock,
      {{{"count", asAddr}, {"count_rate", asAddr}, {"count_max", asAddr}}},
      /*isElemental=*/false},
     {"transfer",
      &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}}},
      /*isElemental=*/false},
     {"unpack",
      &I::genUnpack,
      {{{"vector", asBox}, {"mask", asBox}, {"field", asBox}}},
      /*isElemental=*/false},
if (args.size() == 3) {
     fir::runtime::genUbound(builder, loc, resultIrBox, fir::getBase(args[0]),
                             kind);
 
     return readAndAddCleanUp(resultMutableBox, resultType, "UBOUND");
   }
   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,
                             llvm::ArrayRef<fir::ExtendedValue> args) {
   assert(args.size() == 3);
 
   // Handle required vector argument
   mlir::Value vector = builder.createBox(loc, args[0]);

flang/test/Lower/Intrinsics/trim.f90

+! 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
+