| Message ID | 1541364511.30044.4.camel@med.uni-goettingen.de |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,C,ADA] use function descriptors instead of trampolines in C | expand |
Is there a change that we can move forward with this? I think this is a very useful feature and might be especially important if GCC is going to activate -Wtrampoline with -Wall on some architectures. Best, Martin Am Sonntag, den 04.11.2018, 21:48 +0100 schrieb Martin Uecker: > Hi Joseph, > > here is a new version of this patch which adds a warning > for targets which do not support -fno-trampolines and > only runs the test case on architectures where this is > supported. It seems that documentation for this general > feature has improved in the meantime so I only mention > C as supported. > > > Best, > Martin > > diff --git a/gcc/ChangeLog b/gcc/ChangeLog > index 5cf291da2d5..e75500c647a 100644 > --- a/gcc/ChangeLog > +++ b/gcc/ChangeLog > @@ -1,3 +1,13 @@ > +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> > + > + * common.opt (flag_trampolines): Change default. > + * calls.c (prepare_call_address): Remove check for > + flag_trampolines. Decision is now made in FEs. > + * tree-nested.c (convert_tramp_reference_op): Likewise. > + * toplev.c (process_options): Add warning for -fno- > trampolines on > + unsupported targets. > + * doc/invoke.texi (-fno-trampolines): Document support for > C. > + > 2018-11-02 Aaron Sawdey <acsawdey@linux.ibm.com> > > * config/rs6000/rs6000-string.c > (expand_strncmp_gpr_sequence): Pay > diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog > index 73666129f55..a7462edfc71 100644 > --- a/gcc/ada/ChangeLog > +++ b/gcc/ada/ChangeLog > @@ -1,3 +1,8 @@ > +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> > + > + * gcc-interface/trans.c (Attribute_to_gnu): Add check for > + flag_trampolines. > + > 2018-10-22 Eric Botcazou <ebotcazou@adacore.com> > > * gcc-interface/utils.c (unchecked_convert): Use local > variables for > diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc- > interface/trans.c > index ce2d43f989e..b79f2373c63 100644 > --- a/gcc/ada/gcc-interface/trans.c > +++ b/gcc/ada/gcc-interface/trans.c > @@ -1753,7 +1753,8 @@ Attribute_to_gnu (Node_Id gnat_node, tree > *gnu_result_type_p, int attribute) > if ((attribute == Attr_Access > || attribute == Attr_Unrestricted_Access) > && targetm.calls.custom_function_descriptors > 0 > - && Can_Use_Internal_Rep (Etype (gnat_node))) > + && Can_Use_Internal_Rep (Etype (gnat_node)) > + && (flag_trampolines != 1)) > FUNC_ADDR_BY_DESCRIPTOR (gnu_expr) = 1; > > /* Otherwise, we need to check that we are not > violating the > @@ -4330,7 +4331,8 @@ Call_to_gnu (Node_Id gnat_node, tree > *gnu_result_type_p, tree gnu_target, > /* If the access type doesn't require foreign-compatible > representation, > be prepared for descriptors. */ > if (targetm.calls.custom_function_descriptors > 0 > - && Can_Use_Internal_Rep (Etype (Prefix (Name > (gnat_node))))) > + && Can_Use_Internal_Rep (Etype (Prefix (Name > (gnat_node)))) > + && (flag_trampolines != 1)) > by_descriptor = true; > } > else if (Nkind (Name (gnat_node)) == N_Attribute_Reference) > diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog > index 708ef5d7da2..62823ccf5c7 100644 > --- a/gcc/c/ChangeLog > +++ b/gcc/c/ChangeLog > @@ -1,3 +1,10 @@ > +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> > + > + * c-objc-common.h: Define > LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS. > + * c-typeck.c (function_to_pointer_conversion): If using > descriptors > + instead of trampolines, amend function address with > + FUNC_ADDR_BY_DESCRIPTOR and calls with > ALL_EXPR_BY_DESCRIPTOR. > + > 2018-10-29 David Malcolm <dmalcolm@redhat.com> > > * c-decl.c (implicit_decl_warning): Update "is there a > suggestion" > diff --git a/gcc/c/c-objc-common.h b/gcc/c/c-objc-common.h > index 78e768c2366..ef039560eb9 100644 > --- a/gcc/c/c-objc-common.h > +++ b/gcc/c/c-objc-common.h > @@ -110,4 +110,7 @@ along with GCC; see the file COPYING3. If not > see > > #undef LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P > #define LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P c_vla_unspec_p > + > +#undef LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS > +#define LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS true > #endif /* GCC_C_OBJC_COMMON */ > diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c > index 9d09b8d65fd..afae9de41e7 100644 > --- a/gcc/c/c-typeck.c > +++ b/gcc/c/c-typeck.c > @@ -1912,7 +1912,13 @@ function_to_pointer_conversion (location_t > loc, tree exp) > if (TREE_NO_WARNING (orig_exp)) > TREE_NO_WARNING (exp) = 1; > > - return build_unary_op (loc, ADDR_EXPR, exp, false); > + tree r = build_unary_op (loc, ADDR_EXPR, exp, false); > + > + if ((TREE_CODE(r) == ADDR_EXPR) > + && (flag_trampolines == 0)) > + FUNC_ADDR_BY_DESCRIPTOR (r) = 1; > + > + return r; > } > > /* Mark EXP as read, not just set, for set but not used -Wunused > @@ -3134,6 +3140,11 @@ build_function_call_vec (location_t loc, > vec<location_t> arg_loc, > else > result = build_call_array_loc (loc, TREE_TYPE (fntype), > function, nargs, argarray); > + > + if ((TREE_CODE (result) == CALL_EXPR) > + && (flag_trampolines == 0)) > + CALL_EXPR_BY_DESCRIPTOR (result) = 1; > + > /* If -Wnonnull warning has been diagnosed, avoid diagnosing it > again > later. */ > if (warned_p && TREE_CODE (result) == CALL_EXPR) > diff --git a/gcc/calls.c b/gcc/calls.c > index 8978d3b42fd..95ab7d8405b 100644 > --- a/gcc/calls.c > +++ b/gcc/calls.c > @@ -230,7 +230,7 @@ prepare_call_address (tree fndecl_or_type, rtx > funexp, rtx static_chain_value, > { > /* If it's an indirect call by descriptor, generate code to > perform > runtime identification of the pointer and load the > descriptor. */ > - if ((flags & ECF_BY_DESCRIPTOR) && !flag_trampolines) > + if (flags & ECF_BY_DESCRIPTOR) > { > const int bit_val = > targetm.calls.custom_function_descriptors; > rtx call_lab = gen_label_rtx (); > diff --git a/gcc/common.opt b/gcc/common.opt > index 2971dc21b1f..8457c93edab 100644 > --- a/gcc/common.opt > +++ b/gcc/common.opt > @@ -2487,7 +2487,7 @@ Common Report Var(flag_tracer) Optimization > Perform superblock formation via tail duplication. > > ftrampolines > -Common Report Var(flag_trampolines) Init(0) > +Common Report Var(flag_trampolines) Init(-1) > For targets that normally need trampolines for nested functions, > always > generate them instead of using descriptors. > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index e290128f535..ccf651c1354 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -13570,7 +13570,8 @@ made executable in order for the program to > work properly. > basis to let the compiler avoid generating them, if it computes that > this > is safe, and replace them with descriptors. Descriptors are made up > of data > only, but the generated code must be prepared to deal with them. As > of this > -writing, @option{-fno-trampolines} is enabled by default only for > Ada. > +writing, @option{-fno-trampolines} is supported only for C and Ada > and > +enabled by default only for Ada. > > Moreover, code compiled with @option{-ftrampolines} and code > compiled with > @option{-fno-trampolines} are not binary compatible if nested > functions are > diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog > index a4d50614537..9c4bce69bd9 100644 > --- a/gcc/testsuite/ChangeLog > +++ b/gcc/testsuite/ChangeLog > @@ -1,3 +1,9 @@ > +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> > + > + * gcc.dg/trampoline-2.c: New test. > + * lib/target-supports.exp > + (check_effective_target_notrampolines): New. > + > 2018-11-02 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> > > * gcc.dg/compat/pr83487-1_y.c: Move dg-skip-if ... > diff --git a/gcc/testsuite/gcc.dg/trampoline-2.c > b/gcc/testsuite/gcc.dg/trampoline-2.c > new file mode 100644 > index 00000000000..06c1cf4f647 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/trampoline-2.c > @@ -0,0 +1,23 @@ > +/* test that nested function work without trampolines for -fno- > trampolines */ > +/* Origin: Martin Uecker <martin.uecker@med.uni-goettingen.de> */ > +/* { dg-require-effective-target notrampolines } */ > +/* { dg-options "-std=gnu11 -O2 -Wtrampolines -fno-trampolines" } */ > + > +static int p(void) { return +1; } > +static int m(void) { return -1; } > +static int z(void) { return 0; } > + > +typedef int (*funptr_t)(void); > + > +static int A(int k, funptr_t a1, funptr_t a2, funptr_t a3, funptr_t > a4, funptr_t a5) > +{ > + int B(void) { return A(--k, B, a1, a2, a3, a4); } > + > + return (k <= 0) ? (a4() + a5()) : (B()); > +} > + > +int main(void) > +{ > + return (0 == A(5, p, m, m, p, z)) ? 0 : 1; > +} > + > diff --git a/gcc/testsuite/lib/target-supports.exp > b/gcc/testsuite/lib/target-supports.exp > index fd74c04d092..a34e966b7c4 100644 > --- a/gcc/testsuite/lib/target-supports.exp > +++ b/gcc/testsuite/lib/target-supports.exp > @@ -916,6 +916,14 @@ proc check_effective_target_scheduling {} { > } "-fschedule-insns"] > } > > +# Return 1 if it is possible to use function descriptors instead of > trampolines, 0 otherwise. > + > +proc check_effective_target_notrampolines {} { > + return [check_no_compiler_messages notrampolines assembly { > + void foo (void) { } > + } "-fno-trampolines"] > +} > + > # Return 1 if trapping arithmetic is available, 0 otherwise. > > proc check_effective_target_trapping {} { > diff --git a/gcc/toplev.c b/gcc/toplev.c > index d7ea11abf53..33ded241a20 100644 > --- a/gcc/toplev.c > +++ b/gcc/toplev.c > @@ -1697,6 +1697,12 @@ process_options (void) > flag_prefetch_loop_arrays = 0; > } > > + if (flag_trampolines == 0 && > targetm.calls.custom_function_descriptors == -1) > + { > + warning_at (UNKNOWN_LOCATION, 0, > + "-fno-trampolines not supported for this target"); > + } > + > /* This combination of options isn't handled for i386 targets and > doesn't > make much sense anyway, so don't allow it. */ > if (flag_prefetch_loop_arrays > 0 && optimize_size) > diff --git a/gcc/tree-nested.c b/gcc/tree-nested.c > index 4579b4c5839..e95c9aea051 100644 > --- a/gcc/tree-nested.c > +++ b/gcc/tree-nested.c > @@ -2499,7 +2499,7 @@ convert_tramp_reference_op (tree *tp, int > *walk_subtrees, void *data) > continue; > > /* Decide whether to generate a descriptor or a trampoline. */ > - descr = FUNC_ADDR_BY_DESCRIPTOR (t) && !flag_trampolines; > + descr = FUNC_ADDR_BY_DESCRIPTOR (t); > > if (descr) > x = lookup_descr_for_decl (i, decl, INSERT);
On 11/4/18 1:48 PM, Uecker, Martin wrote: > Hi Joseph, > > here is a new version of this patch which adds a warning > for targets which do not support -fno-trampolines and > only runs the test case on architectures where this is > supported. It seems that documentation for this general > feature has improved in the meantime so I only mention > C as supported. > > > Best, > Martin > > diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c > index ce2d43f989e..b79f2373c63 100644 > --- a/gcc/ada/gcc-interface/trans.c > +++ b/gcc/ada/gcc-interface/trans.c > @@ -1753,7 +1753,8 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute) > if ((attribute == Attr_Access > || attribute == Attr_Unrestricted_Access) > && targetm.calls.custom_function_descriptors > 0 > - && Can_Use_Internal_Rep (Etype (gnat_node))) > + && Can_Use_Internal_Rep (Etype (gnat_node)) > + && (flag_trampolines != 1)) > FUNC_ADDR_BY_DESCRIPTOR (gnu_expr) = 1; You've got an extraneous set of parenthesis around your flag_trampolines check. Please remove them. > > /* Otherwise, we need to check that we are not violating the > @@ -4330,7 +4331,8 @@ Call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target, > /* If the access type doesn't require foreign-compatible representation, > be prepared for descriptors. */ > if (targetm.calls.custom_function_descriptors > 0 > - && Can_Use_Internal_Rep (Etype (Prefix (Name (gnat_node))))) > + && Can_Use_Internal_Rep (Etype (Prefix (Name (gnat_node)))) > + && (flag_trampolines != 1)) Similarly here. > diff --git a/gcc/c/c-objc-common.h b/gcc/c/c-objc-common.h > index 78e768c2366..ef039560eb9 100644 > --- a/gcc/c/c-objc-common.h > +++ b/gcc/c/c-objc-common.h > @@ -110,4 +110,7 @@ along with GCC; see the file COPYING3. If not see > > #undef LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P > #define LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P c_vla_unspec_p > + > +#undef LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS > +#define LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS true > #endif /* GCC_C_OBJC_COMMON */ I wonder if we even need the lang hook anymore. ISTM that a front-end that wants to use the function descriptors can just set FUNC_ADDR_BY_DESCRIPTOR and we'd use the function descriptor, else we'll use the trampoline. Thoughts? > diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c > index 9d09b8d65fd..afae9de41e7 100644 > --- a/gcc/c/c-typeck.c > +++ b/gcc/c/c-typeck.c > @@ -1912,7 +1912,13 @@ function_to_pointer_conversion (location_t loc, tree exp) > if (TREE_NO_WARNING (orig_exp)) > TREE_NO_WARNING (exp) = 1; > > - return build_unary_op (loc, ADDR_EXPR, exp, false); > + tree r = build_unary_op (loc, ADDR_EXPR, exp, false); > + > + if ((TREE_CODE(r) == ADDR_EXPR) > + && (flag_trampolines == 0)) > + FUNC_ADDR_BY_DESCRIPTOR (r) = 1; > + > + return r; Extraneous parens here too. > } > > /* Mark EXP as read, not just set, for set but not used -Wunused > @@ -3134,6 +3140,11 @@ build_function_call_vec (location_t loc, vec<location_t> arg_loc, > else > result = build_call_array_loc (loc, TREE_TYPE (fntype), > function, nargs, argarray); > + > + if ((TREE_CODE (result) == CALL_EXPR) > + && (flag_trampolines == 0)) > + CALL_EXPR_BY_DESCRIPTOR (result) = 1; > + And here too. > diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp > index fd74c04d092..a34e966b7c4 100644 > --- a/gcc/testsuite/lib/target-supports.exp > +++ b/gcc/testsuite/lib/target-supports.exp > @@ -916,6 +916,14 @@ proc check_effective_target_scheduling {} { > } "-fschedule-insns"] > } > > +# Return 1 if it is possible to use function descriptors instead of trampolines, 0 otherwise. > + > +proc check_effective_target_notrampolines {} { > + return [check_no_compiler_messages notrampolines assembly { > + void foo (void) { } > + } "-fno-trampolines"] > +} > + I think this needs documenting in sourcebuild.texi. Look for "Effective-target" to find the appropriate section. Jeff
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5cf291da2d5..e75500c647a 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,13 @@ +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> + + * common.opt (flag_trampolines): Change default. + * calls.c (prepare_call_address): Remove check for + flag_trampolines. Decision is now made in FEs. + * tree-nested.c (convert_tramp_reference_op): Likewise. + * toplev.c (process_options): Add warning for -fno-trampolines on + unsupported targets. + * doc/invoke.texi (-fno-trampolines): Document support for C. + 2018-11-02 Aaron Sawdey <acsawdey@linux.ibm.com> * config/rs6000/rs6000-string.c (expand_strncmp_gpr_sequence): Pay diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog index 73666129f55..a7462edfc71 100644 --- a/gcc/ada/ChangeLog +++ b/gcc/ada/ChangeLog @@ -1,3 +1,8 @@ +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> + + * gcc-interface/trans.c (Attribute_to_gnu): Add check for + flag_trampolines. + 2018-10-22 Eric Botcazou <ebotcazou@adacore.com> * gcc-interface/utils.c (unchecked_convert): Use local variables for diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c index ce2d43f989e..b79f2373c63 100644 --- a/gcc/ada/gcc-interface/trans.c +++ b/gcc/ada/gcc-interface/trans.c @@ -1753,7 +1753,8 @@ Attribute_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, int attribute) if ((attribute == Attr_Access || attribute == Attr_Unrestricted_Access) && targetm.calls.custom_function_descriptors > 0 - && Can_Use_Internal_Rep (Etype (gnat_node))) + && Can_Use_Internal_Rep (Etype (gnat_node)) + && (flag_trampolines != 1)) FUNC_ADDR_BY_DESCRIPTOR (gnu_expr) = 1; /* Otherwise, we need to check that we are not violating the @@ -4330,7 +4331,8 @@ Call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target, /* If the access type doesn't require foreign-compatible representation, be prepared for descriptors. */ if (targetm.calls.custom_function_descriptors > 0 - && Can_Use_Internal_Rep (Etype (Prefix (Name (gnat_node))))) + && Can_Use_Internal_Rep (Etype (Prefix (Name (gnat_node)))) + && (flag_trampolines != 1)) by_descriptor = true; } else if (Nkind (Name (gnat_node)) == N_Attribute_Reference) diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog index 708ef5d7da2..62823ccf5c7 100644 --- a/gcc/c/ChangeLog +++ b/gcc/c/ChangeLog @@ -1,3 +1,10 @@ +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> + + * c-objc-common.h: Define LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS. + * c-typeck.c (function_to_pointer_conversion): If using descriptors + instead of trampolines, amend function address with + FUNC_ADDR_BY_DESCRIPTOR and calls with ALL_EXPR_BY_DESCRIPTOR. + 2018-10-29 David Malcolm <dmalcolm@redhat.com> * c-decl.c (implicit_decl_warning): Update "is there a suggestion" diff --git a/gcc/c/c-objc-common.h b/gcc/c/c-objc-common.h index 78e768c2366..ef039560eb9 100644 --- a/gcc/c/c-objc-common.h +++ b/gcc/c/c-objc-common.h @@ -110,4 +110,7 @@ along with GCC; see the file COPYING3. If not see #undef LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P #define LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P c_vla_unspec_p + +#undef LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS +#define LANG_HOOKS_CUSTOM_FUNCTION_DESCRIPTORS true #endif /* GCC_C_OBJC_COMMON */ diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c index 9d09b8d65fd..afae9de41e7 100644 --- a/gcc/c/c-typeck.c +++ b/gcc/c/c-typeck.c @@ -1912,7 +1912,13 @@ function_to_pointer_conversion (location_t loc, tree exp) if (TREE_NO_WARNING (orig_exp)) TREE_NO_WARNING (exp) = 1; - return build_unary_op (loc, ADDR_EXPR, exp, false); + tree r = build_unary_op (loc, ADDR_EXPR, exp, false); + + if ((TREE_CODE(r) == ADDR_EXPR) + && (flag_trampolines == 0)) + FUNC_ADDR_BY_DESCRIPTOR (r) = 1; + + return r; } /* Mark EXP as read, not just set, for set but not used -Wunused @@ -3134,6 +3140,11 @@ build_function_call_vec (location_t loc, vec<location_t> arg_loc, else result = build_call_array_loc (loc, TREE_TYPE (fntype), function, nargs, argarray); + + if ((TREE_CODE (result) == CALL_EXPR) + && (flag_trampolines == 0)) + CALL_EXPR_BY_DESCRIPTOR (result) = 1; + /* If -Wnonnull warning has been diagnosed, avoid diagnosing it again later. */ if (warned_p && TREE_CODE (result) == CALL_EXPR) diff --git a/gcc/calls.c b/gcc/calls.c index 8978d3b42fd..95ab7d8405b 100644 --- a/gcc/calls.c +++ b/gcc/calls.c @@ -230,7 +230,7 @@ prepare_call_address (tree fndecl_or_type, rtx funexp, rtx static_chain_value, { /* If it's an indirect call by descriptor, generate code to perform runtime identification of the pointer and load the descriptor. */ - if ((flags & ECF_BY_DESCRIPTOR) && !flag_trampolines) + if (flags & ECF_BY_DESCRIPTOR) { const int bit_val = targetm.calls.custom_function_descriptors; rtx call_lab = gen_label_rtx (); diff --git a/gcc/common.opt b/gcc/common.opt index 2971dc21b1f..8457c93edab 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -2487,7 +2487,7 @@ Common Report Var(flag_tracer) Optimization Perform superblock formation via tail duplication. ftrampolines -Common Report Var(flag_trampolines) Init(0) +Common Report Var(flag_trampolines) Init(-1) For targets that normally need trampolines for nested functions, always generate them instead of using descriptors. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index e290128f535..ccf651c1354 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -13570,7 +13570,8 @@ made executable in order for the program to work properly. basis to let the compiler avoid generating them, if it computes that this is safe, and replace them with descriptors. Descriptors are made up of data only, but the generated code must be prepared to deal with them. As of this -writing, @option{-fno-trampolines} is enabled by default only for Ada. +writing, @option{-fno-trampolines} is supported only for C and Ada and +enabled by default only for Ada. Moreover, code compiled with @option{-ftrampolines} and code compiled with @option{-fno-trampolines} are not binary compatible if nested functions are diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index a4d50614537..9c4bce69bd9 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2018-11-03 Martin Uecker <martin.uecker@med.uni-goettingen.de> + + * gcc.dg/trampoline-2.c: New test. + * lib/target-supports.exp + (check_effective_target_notrampolines): New. + 2018-11-02 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> * gcc.dg/compat/pr83487-1_y.c: Move dg-skip-if ... diff --git a/gcc/testsuite/gcc.dg/trampoline-2.c b/gcc/testsuite/gcc.dg/trampoline-2.c new file mode 100644 index 00000000000..06c1cf4f647 --- /dev/null +++ b/gcc/testsuite/gcc.dg/trampoline-2.c @@ -0,0 +1,23 @@ +/* test that nested function work without trampolines for -fno-trampolines */ +/* Origin: Martin Uecker <martin.uecker@med.uni-goettingen.de> */ +/* { dg-require-effective-target notrampolines } */ +/* { dg-options "-std=gnu11 -O2 -Wtrampolines -fno-trampolines" } */ + +static int p(void) { return +1; } +static int m(void) { return -1; } +static int z(void) { return 0; } + +typedef int (*funptr_t)(void); + +static int A(int k, funptr_t a1, funptr_t a2, funptr_t a3, funptr_t a4, funptr_t a5) +{ + int B(void) { return A(--k, B, a1, a2, a3, a4); } + + return (k <= 0) ? (a4() + a5()) : (B()); +} + +int main(void) +{ + return (0 == A(5, p, m, m, p, z)) ? 0 : 1; +} + diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp index fd74c04d092..a34e966b7c4 100644 --- a/gcc/testsuite/lib/target-supports.exp +++ b/gcc/testsuite/lib/target-supports.exp @@ -916,6 +916,14 @@ proc check_effective_target_scheduling {} { } "-fschedule-insns"] } +# Return 1 if it is possible to use function descriptors instead of trampolines, 0 otherwise. + +proc check_effective_target_notrampolines {} { + return [check_no_compiler_messages notrampolines assembly { + void foo (void) { } + } "-fno-trampolines"] +} + # Return 1 if trapping arithmetic is available, 0 otherwise. proc check_effective_target_trapping {} { diff --git a/gcc/toplev.c b/gcc/toplev.c index d7ea11abf53..33ded241a20 100644 --- a/gcc/toplev.c +++ b/gcc/toplev.c @@ -1697,6 +1697,12 @@ process_options (void) flag_prefetch_loop_arrays = 0; } + if (flag_trampolines == 0 && targetm.calls.custom_function_descriptors == -1) + { + warning_at (UNKNOWN_LOCATION, 0, + "-fno-trampolines not supported for this target"); + } + /* This combination of options isn't handled for i386 targets and doesn't make much sense anyway, so don't allow it. */ if (flag_prefetch_loop_arrays > 0 && optimize_size) diff --git a/gcc/tree-nested.c b/gcc/tree-nested.c index 4579b4c5839..e95c9aea051 100644 --- a/gcc/tree-nested.c +++ b/gcc/tree-nested.c @@ -2499,7 +2499,7 @@ convert_tramp_reference_op (tree *tp, int *walk_subtrees, void *data) continue; /* Decide whether to generate a descriptor or a trampoline. */ - descr = FUNC_ADDR_BY_DESCRIPTOR (t) && !flag_trampolines; + descr = FUNC_ADDR_BY_DESCRIPTOR (t); if (descr) x = lookup_descr_for_decl (i, decl, INSERT);