[flang-commits] [flang] [Flang]: Lowering reference to functions that return a procedure pointer (PR #78194)

Daniel Chen via flang-commits flang-commits at lists.llvm.org
Wed Jan 24 10:17:17 PST 2024


https://github.com/DanielCChen updated https://github.com/llvm/llvm-project/pull/78194

>From 8760b1b0768412f9aaf5858120648d0e5030b793 Mon Sep 17 00:00:00 2001
From: cdchen-ca <cdchen at ca.ibm.com>
Date: Mon, 15 Jan 2024 12:17:34 -0500
Subject: [PATCH 1/4] [Flang]: Lowering reference to functions that return a
 procedure pointer.

---
 flang/lib/Lower/CallInterface.cpp      | 64 +++++++++++++-------------
 flang/lib/Lower/ConvertCall.cpp        | 11 ++++-
 flang/lib/Lower/ConvertExprToHLFIR.cpp | 11 +++--
 3 files changed, 51 insertions(+), 35 deletions(-)

diff --git a/flang/lib/Lower/CallInterface.cpp b/flang/lib/Lower/CallInterface.cpp
index 45487197fcbbbe7..a7a69fffe906276 100644
--- a/flang/lib/Lower/CallInterface.cpp
+++ b/flang/lib/Lower/CallInterface.cpp
@@ -1115,39 +1115,41 @@ class Fortran::lower::CallInterfaceImpl {
       const Fortran::evaluate::characteristics::FunctionResult &result) {
     using Attr = Fortran::evaluate::characteristics::FunctionResult::Attr;
     mlir::Type mlirType;
-    if (auto proc{result.IsProcedurePointer()})
+    if (auto proc{result.IsProcedurePointer()}) {
       mlirType = fir::BoxProcType::get(
           &mlirContext, getProcedureType(*proc, interface.converter));
-    else {
-      const Fortran::evaluate::characteristics::TypeAndShape *typeAndShape =
-          result.GetTypeAndShape();
-      assert(typeAndShape && "expect type for non proc pointer result");
-      mlirType = translateDynamicType(typeAndShape->type());
-      fir::SequenceType::Shape bounds = getBounds(typeAndShape->shape());
-      const auto *resTypeAndShape{result.GetTypeAndShape()};
-      bool resIsPolymorphic =
-          resTypeAndShape && resTypeAndShape->type().IsPolymorphic();
-      bool resIsAssumedType =
-          resTypeAndShape && resTypeAndShape->type().IsAssumedType();
-      if (!bounds.empty())
-        mlirType = fir::SequenceType::get(bounds, mlirType);
-      if (result.attrs.test(Attr::Allocatable))
-        mlirType = fir::wrapInClassOrBoxType(
-            fir::HeapType::get(mlirType), resIsPolymorphic, resIsAssumedType);
-      if (result.attrs.test(Attr::Pointer))
-        mlirType =
-            fir::wrapInClassOrBoxType(fir::PointerType::get(mlirType),
-                                      resIsPolymorphic, resIsAssumedType);
-
-      if (fir::isa_char(mlirType)) {
-        // Character scalar results must be passed as arguments in lowering so
-        // that an assumed length character function callee can access the
-        // result length. A function with a result requiring an explicit
-        // interface does not have to be compatible with assumed length
-        // function, but most compilers supports it.
-        handleImplicitCharacterResult(typeAndShape->type());
-        return;
-      }
+      addFirResult(mlirType, FirPlaceHolder::resultEntityPosition,
+                   Property::Value);
+      return;
+    }
+
+    const Fortran::evaluate::characteristics::TypeAndShape *typeAndShape =
+        result.GetTypeAndShape();
+    assert(typeAndShape && "expect type for non proc pointer result");
+    mlirType = translateDynamicType(typeAndShape->type());
+    fir::SequenceType::Shape bounds = getBounds(typeAndShape->shape());
+    const auto *resTypeAndShape{result.GetTypeAndShape()};
+    bool resIsPolymorphic =
+        resTypeAndShape && resTypeAndShape->type().IsPolymorphic();
+    bool resIsAssumedType =
+        resTypeAndShape && resTypeAndShape->type().IsAssumedType();
+    if (!bounds.empty())
+      mlirType = fir::SequenceType::get(bounds, mlirType);
+    if (result.attrs.test(Attr::Allocatable))
+      mlirType = fir::wrapInClassOrBoxType(fir::HeapType::get(mlirType),
+                                           resIsPolymorphic, resIsAssumedType);
+    if (result.attrs.test(Attr::Pointer))
+      mlirType = fir::wrapInClassOrBoxType(fir::PointerType::get(mlirType),
+                                           resIsPolymorphic, resIsAssumedType);
+
+    if (fir::isa_char(mlirType)) {
+      // Character scalar results must be passed as arguments in lowering so
+      // that an assumed length character function callee can access the
+      // result length. A function with a result requiring an explicit
+      // interface does not have to be compatible with assumed length
+      // function, but most compilers supports it.
+      handleImplicitCharacterResult(typeAndShape->type());
+      return;
     }
 
     addFirResult(mlirType, FirPlaceHolder::resultEntityPosition,
diff --git a/flang/lib/Lower/ConvertCall.cpp b/flang/lib/Lower/ConvertCall.cpp
index 57ac9d0652b3176..a7f617f4264eba4 100644
--- a/flang/lib/Lower/ConvertCall.cpp
+++ b/flang/lib/Lower/ConvertCall.cpp
@@ -156,7 +156,10 @@ fir::ExtendedValue Fortran::lower::genCallOpAndResult(
   using PassBy = Fortran::lower::CallerInterface::PassEntityBy;
   // Handle cases where caller must allocate the result or a fir.box for it.
   bool mustPopSymMap = false;
-  if (caller.mustMapInterfaceSymbols()) {
+
+  // Is procedure pointer functin result.
+  bool isProcedurePointer = resultType->isa<fir::BoxProcType>();
+  if (!isProcedurePointer && caller.mustMapInterfaceSymbols()) {
     symMap.pushScope();
     mustPopSymMap = true;
     Fortran::lower::mapCallInterfaceSymbols(converter, caller, symMap);
@@ -202,6 +205,8 @@ fir::ExtendedValue Fortran::lower::genCallOpAndResult(
     llvm::SmallVector<mlir::Value> lengths;
     if (!caller.callerAllocateResult())
       return {};
+    if (isProcedurePointer)
+      return {};
     mlir::Type type = caller.getResultStorageType();
     if (type.isa<fir::SequenceType>())
       caller.walkResultExtents([&](const Fortran::lower::SomeExpr &e) {
@@ -440,6 +445,7 @@ fir::ExtendedValue Fortran::lower::genCallOpAndResult(
       callResult = call.getResult(0);
   }
 
+  // if (!isProcedurePointer && caller.mustSaveResult()) {
   if (caller.mustSaveResult()) {
     assert(allocatedResult.has_value());
     builder.create<fir::SaveResultOp>(loc, callResult,
@@ -1301,6 +1307,9 @@ genUserCall(Fortran::lower::PreparedActualArguments &loweredActuals,
       loc, callContext.converter, callContext.symMap, callContext.stmtCtx,
       caller, callSiteType, callContext.resultType,
       callContext.isElementalProcWithArrayArgs());
+  // For procedure pointer function result, just return the call.
+  if (callContext.resultType->isa<fir::BoxProcType>())
+    return hlfir::EntityWithAttributes(fir::getBase(result));
 
   /// Clean-up associations and copy-in.
   for (auto cleanUp : callCleanUps)
diff --git a/flang/lib/Lower/ConvertExprToHLFIR.cpp b/flang/lib/Lower/ConvertExprToHLFIR.cpp
index a3ad10978e59861..f970100f234c4ac 100644
--- a/flang/lib/Lower/ConvertExprToHLFIR.cpp
+++ b/flang/lib/Lower/ConvertExprToHLFIR.cpp
@@ -1425,9 +1425,14 @@ class HlfirBuilder {
   }
 
   hlfir::EntityWithAttributes gen(const Fortran::evaluate::ProcedureRef &expr) {
-    TODO(
-        getLoc(),
-        "lowering function references that return procedure pointers to HLFIR");
+    fir::FirOpBuilder &builder = getBuilder();
+    Fortran::evaluate::ProcedureDesignator proc{expr.proc()};
+    auto procTy{Fortran::lower::translateSignature(proc, getConverter())};
+    mlir::Type resType = fir::BoxProcType::get(builder.getContext(), procTy);
+    auto result = Fortran::lower::convertCallToHLFIR(
+        getLoc(), getConverter(), expr, resType, getSymMap(), getStmtCtx());
+    assert(result.has_value());
+    return *result;
   }
 
   template <typename T>

>From 850c0b47ea0a8cc13a8a0069a2dfd0fa051e4755 Mon Sep 17 00:00:00 2001
From: cdchen-ca <cdchen at ca.ibm.com>
Date: Mon, 15 Jan 2024 12:24:01 -0500
Subject: [PATCH 2/4] [Flang]: Lowering reference to functions that return a
 procedure pointer.

---
 flang/lib/Lower/ConvertCall.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/flang/lib/Lower/ConvertCall.cpp b/flang/lib/Lower/ConvertCall.cpp
index a7f617f4264eba4..f76ec5f007e6bb7 100644
--- a/flang/lib/Lower/ConvertCall.cpp
+++ b/flang/lib/Lower/ConvertCall.cpp
@@ -445,7 +445,6 @@ fir::ExtendedValue Fortran::lower::genCallOpAndResult(
       callResult = call.getResult(0);
   }
 
-  // if (!isProcedurePointer && caller.mustSaveResult()) {
   if (caller.mustSaveResult()) {
     assert(allocatedResult.has_value());
     builder.create<fir::SaveResultOp>(loc, callResult,

>From a587fabbcb37bc8577666ea5246f758f5205ccf1 Mon Sep 17 00:00:00 2001
From: cdchen-ca <cdchen at ca.ibm.com>
Date: Mon, 15 Jan 2024 15:31:08 -0500
Subject: [PATCH 3/4] [Flang]: Fix LIT test failures that resultType could be
 null.

---
 flang/lib/Lower/ConvertCall.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/flang/lib/Lower/ConvertCall.cpp b/flang/lib/Lower/ConvertCall.cpp
index f76ec5f007e6bb7..6833ff0749dbc0f 100644
--- a/flang/lib/Lower/ConvertCall.cpp
+++ b/flang/lib/Lower/ConvertCall.cpp
@@ -158,7 +158,7 @@ fir::ExtendedValue Fortran::lower::genCallOpAndResult(
   bool mustPopSymMap = false;
 
   // Is procedure pointer functin result.
-  bool isProcedurePointer = resultType->isa<fir::BoxProcType>();
+  bool isProcedurePointer = resultType && resultType->isa<fir::BoxProcType>();
   if (!isProcedurePointer && caller.mustMapInterfaceSymbols()) {
     symMap.pushScope();
     mustPopSymMap = true;
@@ -1307,7 +1307,7 @@ genUserCall(Fortran::lower::PreparedActualArguments &loweredActuals,
       caller, callSiteType, callContext.resultType,
       callContext.isElementalProcWithArrayArgs());
   // For procedure pointer function result, just return the call.
-  if (callContext.resultType->isa<fir::BoxProcType>())
+  if (callContext.resultType && callContext.resultType->isa<fir::BoxProcType>())
     return hlfir::EntityWithAttributes(fir::getBase(result));
 
   /// Clean-up associations and copy-in.

>From 0f91c978c17fb3bd6248384d18d79115a1dca02b Mon Sep 17 00:00:00 2001
From: cdchen-ca <cdchen at ca.ibm.com>
Date: Wed, 17 Jan 2024 14:05:26 -0500
Subject: [PATCH 4/4] [Flang] Add LIT test.

---
 flang/test/Lower/HLFIR/procedure-pointer.f90 | 62 ++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/flang/test/Lower/HLFIR/procedure-pointer.f90 b/flang/test/Lower/HLFIR/procedure-pointer.f90
index 4ea71eef912a309..013c87a975a244c 100644
--- a/flang/test/Lower/HLFIR/procedure-pointer.f90
+++ b/flang/test/Lower/HLFIR/procedure-pointer.f90
@@ -2,6 +2,7 @@
 ! 1. declaration and initialization
 ! 2. pointer assignment and invocation
 ! 3. procedure pointer argument passing.
+! 3. procedure pointer function result.
 ! RUN: bbc -emit-hlfir -o - %s | FileCheck %s
 
 module m
@@ -244,6 +245,67 @@ subroutine sub9()
 ! CHECK: fir.call @_QPfoo2(%[[VAL_10]]) fastmath<contract> : (!fir.ref<!fir.boxproc<() -> ()>>) -> ()
 end
 
+subroutine sub10()
+use m
+
+  procedure(real_func), pointer :: p1
+! CHECK: %[[VAL_0:.*]] = fir.alloca !fir.boxproc<(!fir.ref<f32>) -> f32> {bindc_name = "p1", uniq_name = "_QFsub10Ep1"}
+! CHECK: %[[VAL_1:.*]] = fir.zero_bits (!fir.ref<f32>) -> f32
+! CHECK: %[[VAL_2:.*]] = fir.emboxproc %[[VAL_1]] : ((!fir.ref<f32>) -> f32) -> !fir.boxproc<(!fir.ref<f32>) -> f32>
+! CHECK: fir.store %[[VAL_2]] to %[[VAL_0]] : !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>
+! CHECK: %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_0]] {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFsub10Ep1"} : (!fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>) -> (!fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>, !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>)
+
+  p1 => reffunc(5)
+! CHECK: %c5_i32 = arith.constant 5 : i32
+! CHECK: %[[VAL_4:.*]]:3 = hlfir.associate %c5_i32 {adapt.valuebyref} : (i32) -> (!fir.ref<i32>, !fir.ref<i32>, i1)
+! CHECK: %[[VAL_5:.*]] = fir.call @_QFsub10Preffunc(%[[VAL_4]]#1) fastmath<contract> : (!fir.ref<i32>) -> !fir.boxproc<(!fir.ref<f32>) -> f32>
+! CHECK: fir.store %[[VAL_5]] to %[[VAL_3]]#0 : !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>
+
+contains
+  function reffunc(arg) result(pp)
+    integer :: arg
+    procedure(real_func), pointer :: pp
+! CHECK: %[[VAL_0:.*]]:2 = hlfir.declare %arg0 {uniq_name = "_QFsub10FreffuncEarg"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+! CHECK: %[[VAL_1:.*]] = fir.alloca !fir.boxproc<(!fir.ref<f32>) -> f32> {bindc_name = "pp", uniq_name = "_QFsub10FreffuncEpp"}
+! CHECK: %[[VAL_2:.*]] = fir.zero_bits (!fir.ref<f32>) -> f32
+! CHECK: %[[VAL_3:.*]] = fir.emboxproc %[[VAL_2]] : ((!fir.ref<f32>) -> f32) -> !fir.boxproc<(!fir.ref<f32>) -> f32>
+! CHECK: fir.store %[[VAL_3]] to %[[VAL_1]] : !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>
+! CHECK: %[[VAL_4:.*]]:2 = hlfir.declare %[[VAL_1]] {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFsub10FreffuncEpp"} : (!fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>) -> (!fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>, !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>)
+
+    pp => real_func
+! CHECK: %[[VAL_5:.*]] = fir.address_of(@_QPreal_func) : (!fir.ref<f32>) -> f32
+! CHECK: %[[VAL_6:.*]] = fir.emboxproc %[[VAL_5]] : ((!fir.ref<f32>) -> f32) -> !fir.boxproc<() -> ()>
+! CHECK: %[[VAL_7:.*]] = fir.convert %[[VAL_6]] : (!fir.boxproc<() -> ()>) -> !fir.boxproc<(!fir.ref<f32>) -> f32>
+! CHECK: fir.store %[[VAL_7]] to %[[VAL_4]]#0 : !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>
+! CHECK: %[[VAL_8:.*]] = fir.load %[[VAL_4]]#1 : !fir.ref<!fir.boxproc<(!fir.ref<f32>) -> f32>>
+! CHECK: return %[[VAL_8]] : !fir.boxproc<(!fir.ref<f32>) -> f32>
+  end
+end
+
+subroutine sub11()
+use m
+  interface
+    function reffunc(arg) result(pp)
+      import
+      integer :: arg
+      procedure(char_func), pointer :: pp
+    end
+  end interface
+
+  procedure(char_func), pointer :: p1
+! CHECK: %[[VAL_0:.*]] = fir.alloca !fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>> {bindc_name = "p1", uniq_name = "_QFsub11Ep1"}
+! CHECK: %[[VAL_1:.*]] = fir.zero_bits (!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>
+! CHECK: %[[VAL_2:.*]] = fir.emboxproc %[[VAL_1]] : ((!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>) -> !fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>
+! CHECK: fir.store %[[VAL_2]] to %[[VAL_0]] : !fir.ref<!fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>>
+! CHECK: %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_0]] {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFsub11Ep1"} : (!fir.ref<!fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>>) -> (!fir.ref<!fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>>, !fir.ref<!fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>>)
+
+  p1 => reffunc(5)
+! CHECK: %c5_i32 = arith.constant 5 : i32
+! CHECK: %[[VAL_4:.*]]:3 = hlfir.associate %c5_i32 {adapt.valuebyref} : (i32) -> (!fir.ref<i32>, !fir.ref<i32>, i1)
+! CHECK: %[[VAL_5:.*]] = fir.call @_QPreffunc(%4#1) fastmath<contract> : (!fir.ref<i32>) -> !fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>
+! CHECK: fir.store %[[VAL_5]] to %[[VAL_3]]#0 : !fir.ref<!fir.boxproc<(!fir.ref<i32>) -> !fir.box<!fir.ptr<!fir.char<1,?>>>>>
+! CHECK: return
+end
 
 ! CHECK-LABEL: fir.global internal @_QFsub1Ep2 : !fir.boxproc<(!fir.ref<f32>) -> f32> {
 ! CHECK: %[[VAL_0:.*]] = fir.zero_bits (!fir.ref<f32>) -> f32



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