On Thu, May 28, 2015 at 2:01 PM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Thu, May 28, 2015 at 1:54 PM, Sriraman Tallam <tmsri...@google.com> wrote: >> On Thu, May 28, 2015 at 12:05 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >>> On Thu, May 28, 2015 at 11:50 AM, Sriraman Tallam <tmsri...@google.com> >>> wrote: >>>> On Thu, May 28, 2015 at 11:42 AM, H.J. Lu <hjl.to...@gmail.com> wrote: >>>>> On Thu, May 28, 2015 at 11:34 AM, Sriraman Tallam <tmsri...@google.com> >>>>> wrote: >>>>>> I have attached a patch that adds the new attribute "noplt". Please >>>>>> review. >>>>>> >>>>>> * config/i386/i386.c (avoid_plt_to_call): New function. >>>>>> (ix86_output_call_insn): Generate indirect call for functions >>>>>> marked with "noplt" attribute. >>>>>> (attribute_spec ix86_attribute_): Define new attribute "noplt". >>>>>> * doc/extend.texi: Document new attribute "noplt". >>>>>> * gcc.target/i386/noplt-1.c: New testcase. >>>>>> * gcc.target/i386/noplt-2.c: New testcase. >>>>>> >>>>> >>>>> 2 comments: >>>>> >>>>> 1. Don't remove "%!" prefix before call/jmp. It is needed for MPX. >>>>> 2. Don't you need to check >>>>> >>>>> && !TARGET_MACHO >>>>> && !TARGET_SEH >>>>> && !TARGET_PECOFF >>>>> >>>>> since it only works for ELF. >>>> >>>> Ok, I will make this change. OTOH, is it just better to piggy-back on >>>> existing -fno-plt change by Alex in calls.c >>>> and do this: >>>> >>>> Index: calls.c >>>> =================================================================== >>>> --- calls.c (revision 223720) >>>> +++ calls.c (working copy) >>>> @@ -226,9 +226,11 @@ prepare_call_address (tree fndecl_or_type, rtx fun >>>> && targetm.small_register_classes_for_mode_p (FUNCTION_MODE)) >>>> ? force_not_mem (memory_address (FUNCTION_MODE, funexp)) >>>> : memory_address (FUNCTION_MODE, funexp)); >>>> - else if (flag_pic && !flag_plt && fndecl_or_type >>>> + else if (fndecl_or_type >>>> && TREE_CODE (fndecl_or_type) == FUNCTION_DECL >>>> - && !targetm.binds_local_p (fndecl_or_type)) >>>> + && !targetm.binds_local_p (fndecl_or_type) >>>> + && ((flag_pic && !flag_plt) >>>> + || (lookup_attribute ("noplt", DECL_ATTRIBUTES(fndecl_or_type))))) >>>> { >>>> funexp = force_reg (Pmode, funexp); >>>> } >>>> >>> >>> Does it work on non-PIC calls? >> >> You are right, it doesnt work. I have attached the patch with the >> changes you mentioned. >> > > Since direct_p is true, do wee need > > + if (GET_CODE (call_op) != SYMBOL_REF > + || SYMBOL_REF_LOCAL_P (call_op)) > + return false;
We do need it right because for this case below, I do not want an indirect call: __attribute__((noplt)) int foo() { return 0; } int main() { return foo(); } Assuming foo is not inlined, if I remove the lines you mentioned, I will get an indirect call which is unnecessary. Thanks Sri > > H.J.