Hi Henri! Am 31.05.26 um 8:01 PM schrieb Henri Menke:
gfortran already understands the !GCC$ ATTRIBUTES NOINLINE directive to suppress inlining of a procedure, but there was no way to request the opposite, equivalent to the C always_inline attribute.This adds a FORCEINLINE attribute usable as !GCC$ ATTRIBUTES forceinline :: my_procedure Since Fortran has no 'inline' keyword, the translation sets both DECL_DECLARED_INLINE_P and DECL_DISREGARD_INLINE_LIMITS on the function declaration; setting only the latter would make the middle-end warn that the always-inline function "might not be inlinable". FORCEINLINE and NOINLINE are mutually exclusive. In the middle-end the DECL_UNINLINABLE flag set by NOINLINE always takes precedence, so a combination of the two would silently ignore FORCEINLINE. To avoid that surprise the directive parser warns and drops FORCEINLINE when both are applied to the same procedure, whether in one directive or in two.
While I think that options controlling inlining are desirable, I wonder if "FORCEINLINE" is a good choice. Also, why is there no regular "INLINE"? A commercial Fortran compiler I use at work supports "INLINE" and "ALWAYS_INLINE" with semantics comparable to gcc. My preference would be to follow this convention also for gfortran. (The Intel compiler has INLINE and FORCEINLINE, but according to the documentation these are used differently (and at the call site!), so there would be potential confusion of users.) A real problem of your patch is that it shifts the enums EXT_ATTR_*, after which the module files compiler from previous versions of gfortran are incompatible with those after the patch. This must be fixed. Harald
Bootstrapped and regtested on x86_64-pc-linux-gnu (--enable-languages=c,c++,fortran): all three stages built and the stage 2/3 comparison succeeded, and the gfortran testsuite shows no regressions (75375 expected passes, 335 expected failures, 0 unexpected failures), with the two new tests passing. gcc/fortran/ChangeLog: * gfortran.h (enum ext_attr_id_t): Add EXT_ATTR_FORCEINLINE. * decl.cc (ext_attr_list): Add "forceinline". (gfc_match_gcc_attributes): Warn about and drop FORCEINLINE when it is combined with NOINLINE on the same symbol. * trans-decl.cc (build_function_decl): Handle EXT_ATTR_FORCEINLINE by setting DECL_DECLARED_INLINE_P and DECL_DISREGARD_INLINE_LIMITS. * gfortran.texi (ATTRIBUTES directive): Document FORCEINLINE. gcc/testsuite/ChangeLog: * gfortran.dg/forceinline_1.f90: New test. * gfortran.dg/forceinline_2.f90: New test. Signed-off-by: Henri Menke <[email protected]> --- gcc/fortran/decl.cc | 13 +++++++++++ gcc/fortran/gfortran.h | 1 + gcc/fortran/gfortran.texi | 5 ++++ gcc/fortran/trans-decl.cc | 9 +++++++ gcc/testsuite/gfortran.dg/forceinline_1.f90 | 26 +++++++++++++++++++++ gcc/testsuite/gfortran.dg/forceinline_2.f90 | 14 +++++++++++ 6 files changed, 68 insertions(+) create mode 100644 gcc/testsuite/gfortran.dg/forceinline_1.f90 create mode 100644 gcc/testsuite/gfortran.dg/forceinline_2.f90 diff --git a/gcc/fortran/decl.cc b/gcc/fortran/decl.cc index 166b10d4cd4..aa5b291ac41 100644 --- a/gcc/fortran/decl.cc +++ b/gcc/fortran/decl.cc @@ -12847,6 +12847,7 @@ const ext_attr_t ext_attr_list[] = { { "no_arg_check", EXT_ATTR_NO_ARG_CHECK, NULL }, { "deprecated", EXT_ATTR_DEPRECATED, NULL }, { "noinline", EXT_ATTR_NOINLINE, NULL }, + { "forceinline", EXT_ATTR_FORCEINLINE, NULL }, { "noreturn", EXT_ATTR_NORETURN, NULL }, { "weak", EXT_ATTR_WEAK, NULL }, { NULL, EXT_ATTR_LAST, NULL } @@ -12925,6 +12926,18 @@ gfc_match_gcc_attributes (void)sym->attr.ext_attr |= attr.ext_attr; + /* FORCEINLINE and NOINLINE are mutually exclusive. In the middle-end+ DECL_UNINLINABLE (set by NOINLINE) always wins, so FORCEINLINE would + be silently ignored. Warn and drop it instead. */ + if ((sym->attr.ext_attr & (1 << EXT_ATTR_FORCEINLINE)) + && (sym->attr.ext_attr & (1 << EXT_ATTR_NOINLINE))) + { + gfc_warning (0, "Attribute %<FORCEINLINE%> at %C is incompatible " + "with %<NOINLINE%> for %qs and will be ignored", + sym->name); + sym->attr.ext_attr &= ~(1 << EXT_ATTR_FORCEINLINE); + } + if (gfc_match_eos () == MATCH_YES) break;diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.hindex 37a8582e36d..440ad050bcb 100644 --- a/gcc/fortran/gfortran.h +++ b/gcc/fortran/gfortran.h @@ -886,6 +886,7 @@ typedef enum EXT_ATTR_NO_ARG_CHECK, EXT_ATTR_DEPRECATED, EXT_ATTR_NOINLINE, + EXT_ATTR_FORCEINLINE, EXT_ATTR_NORETURN, EXT_ATTR_WEAK, EXT_ATTR_LAST, EXT_ATTR_NUM = EXT_ATTR_LAST diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi index a930cc1dc9c..255a9235f60 100644 --- a/gcc/fortran/gfortran.texi +++ b/gcc/fortran/gfortran.texi @@ -3397,6 +3397,11 @@ requires an explicit interface. deprecated procedure, variable or parameter; the warning can be suppressed with @option{-Wno-deprecated-declarations}. @item @code{NOINLINE} -- prevent inlining given function. +@item @code{FORCEINLINE} -- force inlining of a given function, ignoring the +inlining size limits. This is the counterpart of @code{NOINLINE} and +corresponds to the C @code{always_inline} attribute. @code{FORCEINLINE} and +@code{NOINLINE} are mutually exclusive; specifying both for the same procedure +makes @code{FORCEINLINE} ignored with a warning. @item @code{NORETURN} -- add a hint that a given function cannot return. @item @code{WEAK} -- emit the declaration of an external symbol as a weak symbol rather than a global. This is primarily useful in defining library diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc index 1bcbfdfd2c9..da291c976ba 100644 --- a/gcc/fortran/trans-decl.cc +++ b/gcc/fortran/trans-decl.cc @@ -2652,6 +2652,15 @@ build_function_decl (gfc_symbol * sym, bool global) if (attr.ext_attr & (1 << EXT_ATTR_NOINLINE)) DECL_UNINLINABLE (fndecl) = 1;+ /* Mark forceinline functions. Fortran has no 'inline' keyword, so set+ DECL_DECLARED_INLINE_P as well; otherwise the middle-end warns that the + always-inline function "might not be inlinable". */ + if (attr.ext_attr & (1 << EXT_ATTR_FORCEINLINE)) + { + DECL_DECLARED_INLINE_P (fndecl) = 1; + DECL_DISREGARD_INLINE_LIMITS (fndecl) = 1; + } + /* Mark noreturn functions. */ if (attr.ext_attr & (1 << EXT_ATTR_NORETURN)) TREE_THIS_VOLATILE (fndecl) = 1; diff --git a/gcc/testsuite/gfortran.dg/forceinline_1.f90 b/gcc/testsuite/gfortran.dg/forceinline_1.f90 new file mode 100644 index 00000000000..2058c088662 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/forceinline_1.f90 @@ -0,0 +1,26 @@ +! { dg-do compile } +! { dg-options "-O -fdump-tree-optimized" } +! +! Verify that !GCC$ ATTRIBUTES forceinline forces inlining: the helper +! procedure is inlined into its caller and no standalone call remains. + +subroutine caller(a, n) + implicit none + integer, intent(in) :: n + real, intent(inout) :: a(n) + call helper(a, n) + call helper(a, n) +contains + subroutine helper(x, m) + implicit none + integer, intent(in) :: m + real, intent(inout) :: x(m) +!GCC$ ATTRIBUTES forceinline :: helper + integer :: i + do i = 1, m + x(i) = x(i) + 1.0 + end do + end subroutine helper +end subroutine caller + +! { dg-final { scan-tree-dump-not "helper" "optimized" } } diff --git a/gcc/testsuite/gfortran.dg/forceinline_2.f90 b/gcc/testsuite/gfortran.dg/forceinline_2.f90 new file mode 100644 index 00000000000..44e4c107034 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/forceinline_2.f90 @@ -0,0 +1,14 @@ +! { dg-do compile } +! +! FORCEINLINE and NOINLINE are mutually exclusive. Specifying both for the +! same procedure must warn and drop FORCEINLINE, whether they appear in one +! directive or in separate directives. + +subroutine foo() +!GCC$ ATTRIBUTES forceinline, noinline :: foo ! { dg-warning "FORCEINLINE. at .1. is incompatible with .NOINLINE." } +end subroutine foo + +subroutine bar() +!GCC$ ATTRIBUTES forceinline :: bar +!GCC$ ATTRIBUTES noinline :: bar ! { dg-warning "FORCEINLINE. at .1. is incompatible with .NOINLINE." } +end subroutine bar
