gcc compatibility: silent -finline-limit=1234 & -finline-limit

[bubbles231]

Summary

As clang doesn't support function in-lining, this gcc flag can safely
ignored. Note: some sloppy Makefiles set the flag without a value.
Both of these arguments are now ignored and tests have been updated as appropriate.

[sylvestre.ledru]

We have 9 occurrences of this in our Debian rebuilds:
http://clang.debian.net/status.php?version=3.4.2&key=UNKNOWN_ARG

[sylvestre.ledru]

lgtm

[• rafael]

adding cfe-commits

[joerg]

I see two patches in pkgsrc removing use of this and the related -finline-functions-called-once. I don't think this option is popular enough for supporting it.

[sylvestre.ledru]

We have 8 occurrences in Debian of -finline-limit=XXXX and we are already ignoring -finline-limit. I don't see any issue to do the same with the value.

[rnk]

One alternative is to recognize the flag, but warn on it. An easy way to do this with a poor diagnostic experience is to simply add it to our option table, don't put it into clang_ignored_f_Group, and don't check it in the driver. Clang will emit 'warning: argument unused during compilation '-finline-limit=1234''.

For extra credit, we could have a diagnostic like "ignoring GCC optimization tuning flag" and use that for all GCC optimization flags that don't have analogues in Clang/LLVM.

include/clang/Driver/Options.td

1561

This should be finline_limit_EQ.

[joerg]

I agree, the second approach sounds like the best way forward.

[bubbles231]

I am closing this revision because I have submitted a patch that
fixes -finline-limit and more: http://reviews.llvm.org/D4461.

include/clang/Driver/Options.td

 
 defm eliminate_unused_debug_types : BooleanFFlag<"eliminate-unused-debug-types">, Group<clang_ignored_f_Group>;
 defm float_store : BooleanFFlag<"float-store">, Group<clang_ignored_f_Group>;
 defm function_attribute_list : BooleanFFlag<"function-attribute-list">, Group<clang_ignored_f_Group>;
 defm gcse : BooleanFFlag<"gcse">, Group<clang_ignored_f_Group>;
 defm gnu : BooleanFFlag<"gnu">, Group<clang_ignored_f_Group>;
 defm ident : BooleanFFlag<"ident">, Group<clang_ignored_f_Group>;
 defm implicit_templates : BooleanFFlag<"implicit-templates">, Group<clang_ignored_f_Group>;
+def inline_limit_EQ : Joined<["-"], "finline-limit=">, Group<clang_ignored_f_Group>;
 defm inline_limit : BooleanFFlag<"inline-limit">, Group<clang_ignored_f_Group>;
 defm ivopts : BooleanFFlag<"ivopts">, Group<clang_ignored_f_Group>;
 defm non_call_exceptions : BooleanFFlag<"non-call-exceptions">, Group<clang_ignored_f_Group>;
 defm permissive : BooleanFFlag<"permissive">, Group<clang_ignored_f_Group>;
 defm prefetch_loop_arrays : BooleanFFlag<"prefetch-loop-arrays">, Group<clang_ignored_f_Group>;
 defm printf : BooleanFFlag<"printf">, Group<clang_ignored_f_Group>;
 defm profile : BooleanFFlag<"profile">, Group<clang_ignored_f_Group>;
 defm profile_correction : BooleanFFlag<"profile-correction">, Group<clang_ignored_f_Group>;

test/Driver/clang_f_opts.c

 // RUN:     -funroll-all-loops -fno-unroll-all-loops                          \
 // RUN:     -fuse-ld=gold                                                     \
 // RUN:     -fno-builtin-foobar                                               \
 // RUN:     -fno-builtin-strcat -fno-builtin-strcpy                           \
 // RUN:     -fno-var-tracking                                                 \
 // RUN:     -fno-unsigned-char                                                \
 // RUN:     -fno-signed-char                                                  \
 // RUN:     -fstrength-reduce -fno-strength-reduce                            \
+// RUN:     -finline-limit=1000                                               \
+// RUN:     -finline-limit                                                    \
 // RUN:     %s 2>&1 | FileCheck --check-prefix=IGNORE %s
 // IGNORE-NOT: error: unknown argument
 
 // RUN: %clang -### -fshort-wchar -fno-short-wchar %s 2>&1 | FileCheck -check-prefix=CHECK-WCHAR1 %s
 // RUN: %clang -### -fno-short-wchar -fshort-wchar %s 2>&1 | FileCheck -check-prefix=CHECK-WCHAR2 %s
 // CHECK-WCHAR1: -fno-short-wchar
 // CHECK-WCHAR1-NOT: -fshort-wchar
 // CHECK-WCHAR2: -fshort-wchar
 // CHECK-WCHAR2-NOT: -fno-short-wchar