caio/clang-p2996
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[flang] handle common block used as BIND(C) module variables (#145669)

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Support odd case where a static object is being declared both as a
common block and a BIND(C) module variable name in different modules,
and both modules are used in the same compilation unit.

This is not standard, but happens when using MPI and MPI_F08 in the same
compilation unit, and at least both gfortran and ifx support this.

See added test case for an illustration.
This commit is contained in:
jeanPerier
2025-06-26 12:00:23 +02:00
committed by GitHub
parent a2265423d0
commit 13daf65656
2 changed files with 43 additions and 1 deletions
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7
flang/lib/Lower/ConvertVariable.cpp
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@@ -687,8 +687,13 @@ static void instantiateGlobal(Fortran::lower::AbstractConverter &converter,
}
auto addrOf = builder.create<fir::AddrOfOp>(loc, global.resultType(),
global.getSymbol());
// The type of the global cannot be trusted to be the same as the one
// of the variable as some existing programs map common blocks to
// BIND(C) module variables (e.g. mpi_argv_null in MPI and MPI_F08).
mlir::Type varAddrType = fir::ReferenceType::get(converter.genType(sym));
mlir::Value cast = builder.createConvert(loc, varAddrType, addrOf);
Fortran::lower::StatementContext stmtCtx;
mapSymbolAttributes(converter, var, symMap, stmtCtx, addrOf);
mapSymbolAttributes(converter, var, symMap, stmtCtx, cast);
}
//===----------------------------------------------------------------===//

37
flang/test/Lower/variable-common-viewed-as-module-var.f90 Normal file
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@@ -0,0 +1,37 @@
! RUN: bbc -emit-hlfir %s -o - | FileCheck %s
! Test non standard definition of a common block as a BIND(C) variable.
! This happens when MPI and MPI_F08 are used inside the same compilation
! unit because MPI uses common blocks while MPI_F08 uses BIND(C) variables
! to refer to the same objects (e.g. mpi_argv_null).
module m_common_var
character(1) :: var
common /var_storage/var
end module
module m_bindc_var
character(1), bind(c, name="var_storage_") :: var
end module
subroutine s1()
use m_common_var, only : var
var = "a"
end subroutine
subroutine s2()
use m_bindc_var, only : var
print *, var
end subroutine
call s1()
call s2()
end
! CHECK: fir.global common @var_storage_(dense<0> : vector<1xi8>) {alignment = 1 : i64} : !fir.array<1xi8>
! CHECK-LABEL: func.func @_QPs1
! CHECK: hlfir.declare %{{.*}} typeparams %c1 {uniq_name = "_QMm_common_varEvar"} : (!fir.ref<!fir.char<1>>, index) -> (!fir.ref<!fir.char<1>>, !fir.ref<!fir.char<1>>)
! CHECK-LABEL: func.func @_QPs2
! CHECK: hlfir.declare %{{.*}} typeparams %c1 {fortran_attrs = #fir.var_attrs<bind_c>, uniq_name = "var_storage_"} : (!fir.ref<!fir.char<1>>, index) -> (!fir.ref<!fir.char<1>>, !fir.ref<!fir.char<1>>)