On Tue, Aug 8, 2017 at 12:32 AM, Segher Boessenkool <seg...@kernel.crashing.org> wrote: > Hi Yuri, > > Sorry I missed this. Please cc: me to prevent that from happening.
Segher, Sorry, somehow I missed your reply! > On Fri, Jul 28, 2017 at 05:42:00AM +0100, Yury Gribov wrote: >> This patch fixes issues reported in >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81535 >> >> I removed call to g in pr79439.c because gcc was duplicating the basic >> block with call depending on compiler flags (so scan-assembler-times >> pattern wasn't reliable anymore). I also added alias to prevent >> inlining introduced by recent PR56727 patch. >> >> I added Power-specific pattern in pr56727-2.c testcase and disabled >> testing on Power in pr56727-1.c. >> >> Tested on powerpc64-unknown-linux-gnu. Ok for trunk? > > Did you also test this with -m32? And on powerpc64le-linux, the target > the bug is reported against? The three ABIs are different. No, only tested standard powerpc64. I'll go check other targets then. >> PR target/81535 >> * gcc.dg/pr56727-1.c: Do not check output on Power. >> * gcc.dg/pr56727-2.c: Fix pattern for Power. > > Please name the actual target triple here, i.e. powerpc*-*-* . Makes sense. >> * gcc.target/powerpc/pr79439.c: Prevent inlining. > >> diff -rupN gcc/gcc/testsuite/gcc.dg/pr56727-1.c >> gcc-81535/gcc/testsuite/gcc.dg/pr56727-1.c >> --- gcc/gcc/testsuite/gcc.dg/pr56727-1.c 2017-07-28 02:39:54.770046466 >> +0000 >> +++ gcc-81535/gcc/testsuite/gcc.dg/pr56727-1.c 2017-07-28 >> 04:25:04.805648587 +0000 >> @@ -1,6 +1,6 @@ >> /* { dg-do compile { target fpic } } */ >> /* { dg-options "-O2 -fPIC" } */ >> -/* { dg-final { scan-assembler-not "@(PLT|plt)" { target i?86-*-* >> x86_64-*-* powerpc*-*-* } } } */ >> +/* { dg-final { scan-assembler-not "@(PLT|plt)" { target i?86-*-* >> x86_64-*-* } } } */ >> >> #define define_func(type) \ >> void f_ ## type (type b) { f_ ## type (0); } \ > > Is it correct that current GCC does not do the call via the PLT? Well, it was decided in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56727 that it would be a valid optimization because the only way to expose the difference would be through dlsym hackery. Note that original PowerPC use-case (reported in https://sourceware.org/bugzilla/show_bug.cgi?id=21116) would benefit from this optimization as because PLT call + indirection would be replaced by normal PC-relative call. >> diff -rupN gcc/gcc/testsuite/gcc.dg/pr56727-2.c >> gcc-81535/gcc/testsuite/gcc.dg/pr56727-2.c >> --- gcc/gcc/testsuite/gcc.dg/pr56727-2.c 2017-07-28 02:39:54.770046466 >> +0000 >> +++ gcc-81535/gcc/testsuite/gcc.dg/pr56727-2.c 2017-07-28 >> 04:21:19.195215187 +0000 >> @@ -1,10 +1,10 @@ >> /* { dg-do compile { target fpic } } */ >> /* { dg-options "-O2 -fPIC" } */ >> -/* { dg-final { scan-assembler "@(PLT|plt)" { target i?86-*-* x86_64-*-* >> powerpc*-*-linux* } } } */ >> >> __attribute__((noinline, noclone)) >> void f (short b) >> { >> + __builtin_setjmp (0); /* Prevent tailcall */ >> f (0); >> } >> > > This change is not mentioned in the changelog. Well, this was a minor hack to prevent tailcalling, I thought it does not deserve a comment... >> @@ -14,3 +14,5 @@ void h () >> { >> g (0); >> } >> +/* { dg-final { scan-assembler "@(PLT|plt)" { target i?86-*-* x86_64-*-* } >> } } */ >> +/* { dg-final { scan-assembler "bl f\n\[ \t\]*nop" { target >> powerpc*-*-linux* } } } */ > > Is there a real reason there cannot be a tailcall here? You can write > this as { scan-assembler {\mbl f\s+nop\M} } btw. Yes, setjmp will block tailcall optimization. Will fix the pattern, thanks! >> diff -rupN gcc/gcc/testsuite/gcc.target/powerpc/pr79439.c >> gcc-81535/gcc/testsuite/gcc.target/powerpc/pr79439.c >> --- gcc/gcc/testsuite/gcc.target/powerpc/pr79439.c 2017-07-28 >> 02:39:55.750048426 +0000 >> +++ gcc-81535/gcc/testsuite/gcc.target/powerpc/pr79439.c 2017-07-28 >> 04:13:47.834177237 +0000 >> @@ -8,22 +8,17 @@ >> >> int f (void); >> >> -void >> -g (void) >> -{ >> -} >> - >> int >> rec (int a) >> { >> int ret = 0; >> if (a > 10 && f ()) >> ret += rec (a - 1); >> - g (); >> return a + ret; >> } >> >> +void rec_alias (short) __attribute__ ((alias ("rec"))); >> + >> /* { dg-final { scan-assembler-times {\mbl f\M} 1 } } */ >> -/* { dg-final { scan-assembler-times {\mbl g\M} 1 } } */ >> /* { dg-final { scan-assembler-times {\mbl rec\M} 1 } } */ >> -/* { dg-final { scan-assembler-times {\mnop\M} 3 } } */ >> +/* { dg-final { scan-assembler-times {\mnop\M} 2 } } */ > > The changelog says "prevent inlining", but you actually delete the code. > Is that okay, wasn't the testcase actually testing for something here? TBH at this point I don't remember. I think call to g() didn't add anything to the test so I removed it. Let me comment on this once I retest the patch as discussed above. -Y
