AMD General
> -----Original Message-----
> From: H.J. Lu <[email protected]>
> Sent: Thursday, July 30, 2026 2:37 AM
> To: Roy, Reshma <[email protected]>
> Cc: [email protected]; [email protected]; [email protected]; Kumar,
> Venkataramanan <[email protected]>; Aloor, Raghesh
> <[email protected]>
> Subject: Re: [PATCH, backport gcc-16] x86_cse: Check if DRAP is live with
> DF_LR_IN.
>
> Caution: This message originated from an External Source. Use proper caution
> when opening attachments, clicking links, or responding.
>
>
> On Thu, Jul 30, 2026 at 12:18 AM <[email protected]> wrote:
> >
> > From: Reshma Roy <[email protected]>
> >
> > Backported from master:
> > The DRAP register has no reaching definition on function entry, so it
> > never shows up in DF_LIVE_IN. When collecting the live caller-saved
> > registers, additionally set DRAP's bit whenever it is live-in per
> > DF_LR_IN, so the hoisted TLS call is kept after the DRAP save.
> >
> > PR target/126382
> >
> > gcc/ChangeLog:
> >
> > * config/i386/i386-features.cc (ix86_emit_tls_call): Additional
> > check to see if DRAP register is live in basic block with
> > DF_LR_IN.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.target/i386/pr126382.c: New test.
> >
> > (cherry picked from commit af8dbc9ccf8209007e38a923c3c158e9e8f4396d)
> > ---
> >
> > Hi Richard,
> >
> > This is a backport of the regression fix done for PR126382 to the
> > releases/gcc-16 branch.
> >
> > Master commit: af8dbc9ccf8209007e38a923c3c158e9e8f4396d
> > PR link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126382
> >
> > Bootstrapped and regression tested on x86_64-linux.
> >
> > Given the upcoming 16.2 release, is this OK for the releases/gcc-16
> > branch?
> >
> > Thanks
> > Reshma Roy
> >
> > gcc/config/i386/i386-features.cc | 11 +++++++
> > gcc/testsuite/gcc.target/i386/pr126382.c | 40
> > ++++++++++++++++++++++++
> > 2 files changed, 51 insertions(+)
> > create mode 100644 gcc/testsuite/gcc.target/i386/pr126382.c
> >
> > diff --git a/gcc/config/i386/i386-features.cc
> > b/gcc/config/i386/i386-features.cc
> > index cef1e24da34..ddd5eca5ef0 100644
> > --- a/gcc/config/i386/i386-features.cc
> > +++ b/gcc/config/i386/i386-features.cc
> > @@ -4026,6 +4026,17 @@ ix86_emit_tls_call (rtx tls_set, x86_cse_kind kind,
> basic_block bb,
> > && !fixed_regs[i]
> > && bitmap_bit_p (in, i))
> > bitmap_set_bit (live_caller_saved_regs, i);
> > + if (df_live && crtl->drap_reg)
>
> This should be inside of the
>
> if (kind != X86_CSE_TLSDESC)
>
> block. I properly backported it to GCC 16 for you.
Thanks for fixing the issues and committing the patch!
>
> > + {
> > + /* DRAP has no reaching definition at this point, so df_live drops
> > + it above. Its hard register can also go dead mid-function once
> > + copied elsewhere (e.g. right after the prologue), so query
> > + DF_LR_IN per-block rather than treating it as live whenever
> > + crtl->drap_reg is set. */
> > + i = REGNO (crtl->drap_reg);
> > + if (bitmap_bit_p (DF_LR_IN (bb), i))
> > + bitmap_set_bit (live_caller_saved_regs, i);
> > + }
> >
> > if (bitmap_empty_p (live_caller_saved_regs))
> > {
> > diff --git a/gcc/testsuite/gcc.target/i386/pr126382.c
> > b/gcc/testsuite/gcc.target/i386/pr126382.c
> > new file mode 100644
> > index 00000000000..2ffe0074c21
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/pr126382.c
> > @@ -0,0 +1,40 @@
> > +/* { dg-do compile { target { *-*-linux* && lp64 } } } */
> > +/* { dg-options "-O3 -fPIC -march=x86-64-v4
> > +-fno-asynchronous-unwind-tables -mtls-dialect=gnu" } */
> > +/* Keep labels and directives ('.cfi_startproc', '.cfi_endproc'). */
> > +/* { dg-final { check-function-bodies "**" "" "" { target "*-*-*" }
> > +{^\t?\.} } } */
> > +
> > +/*
> > +**func:
> > +** pushq %rbp
> > +** movq %rsp, %rbp
> > +** pushq %r12
> > +** pushq %r10
> > +** leaq 16\(%rbp\), %r10
> > +** pushq %rbx
> > +** movq %r10, %r12
> > +** subq \$8, %rsp
> > +** data16 leaq FLA_ONE@tlsgd\(%rip\), %rdi
> > +** .value 0x6666
> > +** rex64
> > +** call __tls_get_addr@PLT
> > +**...
> > +*/
> > +
> > +typedef struct
> > +{
> > + long n;
> > + long m_inner;
> > + long n_inner;
> > + int base;
> > + } FLA_Obj;
> > +extern __thread FLA_Obj FLA_ONE, W12; extern long FLA_Obj_length
> > +(FLA_Obj); extern void FLA_Obj_width (FLA_Obj, ...); void func
> > +(FLA_Obj A) {
> > + while (FLA_Obj_length (A))
> > + FLA_Obj_width (FLA_ONE);
> > + FLA_Obj_width (FLA_ONE, W12);
> > +}
> > +
> > +/* { dg-final { scan-assembler-times "call\[ \t\]__tls_get_addr@PLT"
> > +2 } } */
> > --
> > 2.34.1
> >
>
>
> --
> H.J.
Thanks
Reshma Roy
