| Message ID | 2feecb0e-7ec9-1f3c-dfd4-6b40c4c5f518@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | rs6000: Entry point generation for functions using PC-relative addressing | expand |
Hi! On Wed, May 22, 2019 at 06:39:55PM -0500, Bill Schmidt wrote: > @@ -26191,6 +26191,10 @@ rs6000_global_entry_point_needed_p (void) > if (TARGET_SINGLE_PIC_BASE) > return false; > > + /* PC-relative functions never generate a global entry point prologue. */ > + if (rs6000_pcrel_p (cfun)) > + return false; "global_entry_point_needed" is such a confusing name; it isn't what this function is about. "global entry point prologue" like in your comment is much closer to the truth, but also not exactly it. Maybe we should rename this function. And/or split it into two. > + const char *name = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0); This var is only used on some code paths. Factor this better, instead? This ties in with the previous point. > --- /dev/null > +++ b/gcc/testsuite/gcc.target/powerpc/localentry-1.c > @@ -0,0 +1,19 @@ > +/* { dg-do compile } */ > +/* { dg-options "-mcpu=future -O2" } */ > +/* { dg-require-effective-target powerpc_elfv2 } */ > +/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=future" } } */ Lose this last line, use -mdejagnu-cpu=future instead please. Segher
On 5/23/19 6:06 AM, Segher Boessenkool wrote: > Hi! > > On Wed, May 22, 2019 at 06:39:55PM -0500, Bill Schmidt wrote: >> @@ -26191,6 +26191,10 @@ rs6000_global_entry_point_needed_p (void) >> if (TARGET_SINGLE_PIC_BASE) >> return false; >> >> + /* PC-relative functions never generate a global entry point prologue. */ >> + if (rs6000_pcrel_p (cfun)) >> + return false; > "global_entry_point_needed" is such a confusing name; it isn't what this > function is about. "global entry point prologue" like in your comment > is much closer to the truth, but also not exactly it. > > Maybe we should rename this function. And/or split it into two. I think "global entry point prologue" is exactly right, and the function-level comment even says that. So we could change this to rs6000_global_entry_point_prologue_needed_p. A bit chewy but digestible. > >> + const char *name = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0); > This var is only used on some code paths. Factor this better, instead? > This ties in with the previous point. > >> --- /dev/null >> +++ b/gcc/testsuite/gcc.target/powerpc/localentry-1.c >> @@ -0,0 +1,19 @@ >> +/* { dg-do compile } */ >> +/* { dg-options "-mcpu=future -O2" } */ >> +/* { dg-require-effective-target powerpc_elfv2 } */ >> +/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=future" } } */ > Lose this last line, use -mdejagnu-cpu=future instead please. Yeah, sorry, original patch predated that change and I missed it again. Thanks! Bill > > > Segher >
On Thu, May 23, 2019 at 08:56:23AM -0500, Bill Schmidt wrote: > On 5/23/19 6:06 AM, Segher Boessenkool wrote: > > On Wed, May 22, 2019 at 06:39:55PM -0500, Bill Schmidt wrote: > >> @@ -26191,6 +26191,10 @@ rs6000_global_entry_point_needed_p (void) > >> if (TARGET_SINGLE_PIC_BASE) > >> return false; > >> > >> + /* PC-relative functions never generate a global entry point prologue. */ > >> + if (rs6000_pcrel_p (cfun)) > >> + return false; > > "global_entry_point_needed" is such a confusing name; it isn't what this > > function is about. "global entry point prologue" like in your comment > > is much closer to the truth, but also not exactly it. > > > > Maybe we should rename this function. And/or split it into two. > I think "global entry point prologue" is exactly right, and the > function-level comment even says that. So we could change this to > rs6000_global_entry_point_prologue_needed_p. A bit chewy but digestible. So I see the second use really needs the same condition... okay. What it checks is if the function needs a local entry point not equal to the global entry point. Anyway... Not too important, the function isn't used in many places at all. Segher
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index 959e222c9cb..23c6d37ab55 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -26191,6 +26191,10 @@ rs6000_global_entry_point_needed_p (void) if (TARGET_SINGLE_PIC_BASE) return false; + /* PC-relative functions never generate a global entry point prologue. */ + if (rs6000_pcrel_p (cfun)) + return false; + /* Ensure we have a global entry point for thunks. ??? We could avoid that if the target routine doesn't need a global entry point, but we do not know whether this is the case at this point. */ @@ -27545,12 +27549,12 @@ rs6000_output_function_prologue (FILE *file) #endif } + const char *name = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0); + /* ELFv2 ABI r2 setup code and local entry point. This must follow immediately after the global entry point label. */ if (rs6000_global_entry_point_needed_p ()) { - const char *name = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0); - (*targetm.asm_out.internal_label) (file, "LCF", rs6000_pic_labelno); if (TARGET_CMODEL != CMODEL_LARGE) @@ -27601,6 +27605,18 @@ rs6000_output_function_prologue (FILE *file) fputs ("\n", file); } + else if (rs6000_pcrel_p (cfun)) + { + /* All functions compiled to use PC-relative addressing will + have a .localentry value of 0 or 1. For now we set it to + 1 all the time, indicating that the function may clobber + the TOC register r2. Later we may optimize this by setting + it to 0 if the function is a leaf and does not clobber r2. */ + fputs ("\t.localentry\t", file); + assemble_name (file, name); + fputs (",1\n", file); + } + /* Output -mprofile-kernel code. This needs to be done here instead of in output_function_profile since it must go after the ELFv2 ABI local entry point. */ diff --git a/gcc/testsuite/gcc.target/powerpc/localentry-1.c b/gcc/testsuite/gcc.target/powerpc/localentry-1.c new file mode 100644 index 00000000000..15e00d9917e --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/localentry-1.c @@ -0,0 +1,19 @@ +/* { dg-do compile } */ +/* { dg-options "-mcpu=future -O2" } */ +/* { dg-require-effective-target powerpc_elfv2 } */ +/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=future" } } */ + +/* Ensure we generate ".localentry fn,1" for both leaf and non-leaf + functions. */ + +extern int y (int); + +int x (void) +{ + return y (5); +} + +void z (void) { }; + +/* { dg-final { scan-assembler {\.localentry\t\mx,1\M} } } */ +/* { dg-final { scan-assembler {\.localentry\t\mz,1\M} } } */