Message ID | 20181206233433.GB12380@tucnak |
---|---|
State | New |
Headers | show |
Series | Disable -fipa-ra for naked functions (PR target/85593) | expand |
On 12/6/18 4:34 PM, Jakub Jelinek wrote: > Hi! > > The only documented supported content of naked functions is basic asm > statement(s). Those don't have clobbers though, so we should ignore > naked functions for IPA-RA; if they are written the only supported way, > they will appear not to clobber any registers at all and IPA-RA will then > assume they don't clobber any registers. > While naked is a target attribute supported only on a subset of targets, > the generic code already handles it in multiple spots, so I think we can add > another spot rather than introducing a target hook for it. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > 2018-12-07 Jakub Jelinek <jakub@redhat.com> > > PR target/85593 > * final.c (rest_of_handle_final): Don't call collect_fn_hard_reg_usage > for functions with naked attribute. > > * gcc.target/i386/pr85593.c: New test. OK jeff
--- gcc/final.c.jj 2018-11-21 19:38:50.264064648 +0100 +++ gcc/final.c 2018-12-06 19:01:39.052525201 +0100 @@ -4659,7 +4659,11 @@ rest_of_handle_final (void) final_start_function_1 (&first, asm_out_file, &seen, optimize); final_1 (first, asm_out_file, seen, optimize); if (flag_ipa_ra - && !lookup_attribute ("noipa", DECL_ATTRIBUTES (current_function_decl))) + && !lookup_attribute ("noipa", DECL_ATTRIBUTES (current_function_decl)) + /* Functions with naked attributes are supported only with basic asm + statements in the body, thus for supported use cases the information + on clobbered registers is not available. */ + && !lookup_attribute ("naked", DECL_ATTRIBUTES (current_function_decl))) collect_fn_hard_reg_usage (); final_end_function (); --- gcc/testsuite/gcc.target/i386/pr85593.c.jj 2018-12-06 19:19:17.286362641 +0100 +++ gcc/testsuite/gcc.target/i386/pr85593.c 2018-12-06 19:18:47.188850564 +0100 @@ -0,0 +1,30 @@ +/* PR target/85593 */ +/* { dg-do run { target { { i?86-*-linux* x86_64-*-linux* } && lp64 } } } */ +/* { dg-options "-O2" } */ + +__attribute__((naked)) void +bar (void) +{ + asm ("xorl %eax, %eax\n\t" + "xorl %edx, %edx\n\t" + "xorl %ecx, %ecx\n\t" + "xorl %esi, %esi\n\t" + "xorl %edi, %edi\n\t" + "xorl %r8d, %r8d\n\t" + "xorl %r9d, %r9d\n\t" + "xorl %r10d, %r10d\n\t" + "xorl %r11d, %r11d\n\t" + "ret"); +} + +int +main () +{ + int a = 42; + asm ("" : "+r" (a)); + bar (); + asm ("" : "+r" (a)); + if (a != 42) + __builtin_abort (); + return 0; +}