[PATCH] x86-64: Use R10 and R11 for profiling large model with PIC

["H.J. Lu" <hjl.tools@gmail.com>]

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On Fri, Jan 8, 2021 at 4:50 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Fri, Jan 8, 2021 at 1:24 AM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > > Since R10 is preserved when calling mcount, R10 can be used a scratch
> > > register to call mcount in large model.
> >
> > Please mention that R10 can be used as a static chain registers and is
> > preserved when calling mcount for nested functions.
> >
> > > gcc/
> > >
> > > PR target/98482
> > > * config/i386/i386.c (x86_function_profiler): Use R10 to call
> > > mcount in large model. Sorry for large model with PIC.
> > >
> > > gcc/testsuite/
> > >
> > > PR target/98482
> > > * gcc.target/i386/pr98482-1.c: New test.
> > > * gcc.target/i386/pr98482-1.c: Likewise.
> >
> > OK with comment fixes.
> >
> > Thanks,
> > Uros.
> >
> > +    case CM_LARGE:
> > +      /* NB: R10 can be used as a scratch register here since
> > +        R10 is preserved when calling mcount.  */
> >
> > Also mention that R10 can be used as a static chain register and is
> > preserved when calling mcount for nested functions.
> >
> > +      fprintf (file, "1:\tmovabsq\t$%s, %%r10\n\tcall\t*%%r10\n",
> > +       mcount_name);
> > +      break;
>
> This is the patch I am checking in.
>

For NO_PROFILE_COUNTERS targets, R11 is a scratch register.  We can use
R10 and R11 to call mcount in large model with PIC.

OK for master?

Thanks.

-- 
H.J.

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From b2e0bccbdba630a1f7f8b601e19b7302e375e240 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 8 Jan 2021 05:20:19 -0800
Subject: [PATCH] x86-64: Use R10 and R11 for profiling large model with PIC

For NO_PROFILE_COUNTERS targets, R11 is a scratch register.  We can use
R10 and R11 to call mcount in large model with PIC.

gcc/

	PR target/98482
	* config/i386/i386.c (x86_function_profiler): Use R10 and R11
	to call mcount in large model with PIC for NO_PROFILE_COUNTERS
	targets.

gcc/testsuite/

	PR target/98482
	* gcc.target/i386/pr98482-2.c: Updated.
---
 gcc/config/i386/i386.c                    | 10 ++++++++++
 gcc/testsuite/gcc.target/i386/pr98482-2.c |  3 ++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index d3068462fcd..50380865acd 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -20806,7 +20806,17 @@ x86_function_profiler (FILE *file, int labelno ATTRIBUTE_UNUSED)
 		       mcount_name);
 	      break;
 	    case CM_LARGE_PIC:
+#ifdef NO_PROFILE_COUNTERS
+	      fprintf (file, "1:\tmovabsq\t$_GLOBAL_OFFSET_TABLE_-1b, %%r11\n");
+	      fprintf (file, "\tleaq\t1b(%%rip), %%r10\n");
+	      fprintf (file, "\taddq\t%%r11, %%r10\n");
+	      fprintf (file, "\tmovabsq\t$%s@PLTOFF, %%r11\n",
+		       mcount_name);
+	      fprintf (file, "\taddq\t%%r11, %%r10\n");
+	      fprintf (file, "\tcall\t*%%r10\n");
+#else
 	      sorry ("profiling %<-mcmodel=large%> with PIC is not supported");
+#endif
 	      break;
 	    case CM_SMALL_PIC:
 	    case CM_MEDIUM_PIC:
diff --git a/gcc/testsuite/gcc.target/i386/pr98482-2.c b/gcc/testsuite/gcc.target/i386/pr98482-2.c
index aed3ca4b6ff..0ee142db12c 100644
--- a/gcc/testsuite/gcc.target/i386/pr98482-2.c
+++ b/gcc/testsuite/gcc.target/i386/pr98482-2.c
@@ -2,8 +2,9 @@
 /* { dg-require-effective-target mfentry } */
 /* { dg-require-effective-target fpic } */
 /* { dg-options "-fpic -fprofile -mfentry -O2 -mcmodel=large" } */
+/* { dg-final { scan-assembler "movabsq\t\\\$__fentry__@PLTOFF, %r11\n\taddq\t%r11, %r10\n\tcall\t\\*%r10" } } */
 
 void
 func (void)
 {
-} /* { dg-message "sorry, unimplemented: profiling '-mcmodel=large' with PIC is not supported" } */
+}
-- 
2.29.2