[2/2] RISC-V: Enable x0 base relaxation for relax_pc even if --no-relax-gp.
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Commit Message
Let --no-relax-gp only disable the gp relaxation for lui and pcrel
relaxations, since x0 base and gp relaxations are different optimizations
in fact, but just use the same function to handle.
bfd/
* elfnn-riscv.c (_bfd_riscv_relax_pc): Like _bfd_riscv_relax_lui,
set gp to zero when --no-relax-gp, then we should still keep the
x0 base relaxation.
(_bfd_riscv_relax_section): Enable _bfd_riscv_relax_pc when
--no-relax-gp, we will disable the gp relaxation in the
_bfd_riscv_relax_pc.
---
bfd/elfnn-riscv.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Comments
Committed, thanks.
Nelson
On Fri, Apr 21, 2023 at 4:28 PM Nelson Chu <nelson@rivosinc.com> wrote:
> Let --no-relax-gp only disable the gp relaxation for lui and pcrel
> relaxations, since x0 base and gp relaxations are different optimizations
> in fact, but just use the same function to handle.
>
> bfd/
> * elfnn-riscv.c (_bfd_riscv_relax_pc): Like _bfd_riscv_relax_lui,
> set gp to zero when --no-relax-gp, then we should still keep the
> x0 base relaxation.
> (_bfd_riscv_relax_section): Enable _bfd_riscv_relax_pc when
> --no-relax-gp, we will disable the gp relaxation in the
> _bfd_riscv_relax_pc.
> ---
> bfd/elfnn-riscv.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> index 499f51ee857..77a732b6a08 100644
> --- a/bfd/elfnn-riscv.c
> +++ b/bfd/elfnn-riscv.c
> @@ -4721,7 +4721,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
> bool undefined_weak)
> {
> struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table
> (link_info);
> - bfd_vma gp = riscv_global_pointer_value (link_info);
> + bfd_vma gp = htab->params->relax_gp
> + ? riscv_global_pointer_value (link_info)
> + : 0;
>
> BFD_ASSERT (rel->r_offset + 4 <= sec->size);
>
> @@ -4942,7 +4944,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
> || type == R_RISCV_TPREL_LO12_I
> || type == R_RISCV_TPREL_LO12_S)
> relax_func = _bfd_riscv_relax_tls_le;
> - else if (!bfd_link_pic (info) && htab->params->relax_gp
> + else if (!bfd_link_pic (info)
> && (type == R_RISCV_PCREL_HI20
> || type == R_RISCV_PCREL_LO12_I
> || type == R_RISCV_PCREL_LO12_S))
> --
> 2.39.2 (Apple Git-143)
>
>
On Thu, Apr 27, 2023 at 11:29 PM Nelson Chu <nelson@rivosinc.com> wrote:
>
> Committed, thanks.
>
> Nelson
Thanks. I cannot find any information about "x0 base relaxation" on
the Internet.
It is worth a test: if I force `bfd_vma gp = 0;`, check-ld
RUNTESTFLAGS='ld-riscv-elf.exp' will still pass :)
> On Fri, Apr 21, 2023 at 4:28 PM Nelson Chu <nelson@rivosinc.com> wrote:
>
> > Let --no-relax-gp only disable the gp relaxation for lui and pcrel
> > relaxations, since x0 base and gp relaxations are different optimizations
> > in fact, but just use the same function to handle.
> >
> > bfd/
> > * elfnn-riscv.c (_bfd_riscv_relax_pc): Like _bfd_riscv_relax_lui,
> > set gp to zero when --no-relax-gp, then we should still keep the
> > x0 base relaxation.
> > (_bfd_riscv_relax_section): Enable _bfd_riscv_relax_pc when
> > --no-relax-gp, we will disable the gp relaxation in the
> > _bfd_riscv_relax_pc.
> > ---
> > bfd/elfnn-riscv.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> > index 499f51ee857..77a732b6a08 100644
> > --- a/bfd/elfnn-riscv.c
> > +++ b/bfd/elfnn-riscv.c
> > @@ -4721,7 +4721,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
> > bool undefined_weak)
> > {
> > struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table
> > (link_info);
> > - bfd_vma gp = riscv_global_pointer_value (link_info);
> > + bfd_vma gp = htab->params->relax_gp
> > + ? riscv_global_pointer_value (link_info)
> > + : 0;
> >
> > BFD_ASSERT (rel->r_offset + 4 <= sec->size);
> >
> > @@ -4942,7 +4944,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
> > || type == R_RISCV_TPREL_LO12_I
> > || type == R_RISCV_TPREL_LO12_S)
> > relax_func = _bfd_riscv_relax_tls_le;
> > - else if (!bfd_link_pic (info) && htab->params->relax_gp
> > + else if (!bfd_link_pic (info)
> > && (type == R_RISCV_PCREL_HI20
> > || type == R_RISCV_PCREL_LO12_I
> > || type == R_RISCV_PCREL_LO12_S))
> > --
> > 2.39.2 (Apple Git-143)
> >
> >
it called Zero-page Relaxation on psABI spec
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc#zero-page-relaxation
On Fri, Apr 28, 2023 at 3:11 PM Fangrui Song <i@maskray.me> wrote:
>
> On Thu, Apr 27, 2023 at 11:29 PM Nelson Chu <nelson@rivosinc.com> wrote:
> >
> > Committed, thanks.
> >
> > Nelson
>
> Thanks. I cannot find any information about "x0 base relaxation" on
> the Internet.
> It is worth a test: if I force `bfd_vma gp = 0;`, check-ld
> RUNTESTFLAGS='ld-riscv-elf.exp' will still pass :)
>
> > On Fri, Apr 21, 2023 at 4:28 PM Nelson Chu <nelson@rivosinc.com> wrote:
> >
> > > Let --no-relax-gp only disable the gp relaxation for lui and pcrel
> > > relaxations, since x0 base and gp relaxations are different optimizations
> > > in fact, but just use the same function to handle.
> > >
> > > bfd/
> > > * elfnn-riscv.c (_bfd_riscv_relax_pc): Like _bfd_riscv_relax_lui,
> > > set gp to zero when --no-relax-gp, then we should still keep the
> > > x0 base relaxation.
> > > (_bfd_riscv_relax_section): Enable _bfd_riscv_relax_pc when
> > > --no-relax-gp, we will disable the gp relaxation in the
> > > _bfd_riscv_relax_pc.
> > > ---
> > > bfd/elfnn-riscv.c | 6 ++++--
> > > 1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> > > index 499f51ee857..77a732b6a08 100644
> > > --- a/bfd/elfnn-riscv.c
> > > +++ b/bfd/elfnn-riscv.c
> > > @@ -4721,7 +4721,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
> > > bool undefined_weak)
> > > {
> > > struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table
> > > (link_info);
> > > - bfd_vma gp = riscv_global_pointer_value (link_info);
> > > + bfd_vma gp = htab->params->relax_gp
> > > + ? riscv_global_pointer_value (link_info)
> > > + : 0;
> > >
> > > BFD_ASSERT (rel->r_offset + 4 <= sec->size);
> > >
> > > @@ -4942,7 +4944,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
> > > || type == R_RISCV_TPREL_LO12_I
> > > || type == R_RISCV_TPREL_LO12_S)
> > > relax_func = _bfd_riscv_relax_tls_le;
> > > - else if (!bfd_link_pic (info) && htab->params->relax_gp
> > > + else if (!bfd_link_pic (info)
> > > && (type == R_RISCV_PCREL_HI20
> > > || type == R_RISCV_PCREL_LO12_I
> > > || type == R_RISCV_PCREL_LO12_S))
> > > --
> > > 2.39.2 (Apple Git-143)
> > >
> > >
@@ -4721,7 +4721,9 @@ _bfd_riscv_relax_pc (bfd *abfd ATTRIBUTE_UNUSED,
bool undefined_weak)
{
struct riscv_elf_link_hash_table *htab = riscv_elf_hash_table (link_info);
- bfd_vma gp = riscv_global_pointer_value (link_info);
+ bfd_vma gp = htab->params->relax_gp
+ ? riscv_global_pointer_value (link_info)
+ : 0;
BFD_ASSERT (rel->r_offset + 4 <= sec->size);
@@ -4942,7 +4944,7 @@ _bfd_riscv_relax_section (bfd *abfd, asection *sec,
|| type == R_RISCV_TPREL_LO12_I
|| type == R_RISCV_TPREL_LO12_S)
relax_func = _bfd_riscv_relax_tls_le;
- else if (!bfd_link_pic (info) && htab->params->relax_gp
+ else if (!bfd_link_pic (info)
&& (type == R_RISCV_PCREL_HI20
|| type == R_RISCV_PCREL_LO12_I
|| type == R_RISCV_PCREL_LO12_S))