RE: [PATCH] [MIPS] Hazard barrier return support
On Mon, 16 Aug 2021, Dragan Mladjenovic via Gcc-patches wrote:
> I'll respin the tests for mips64r2 and mips64 just in case.
>
> This check would fail for -mips64. GAS accepts jr.hb for both '.set mips64'
> and
> '.set mips64r2' and '.set mips32' for that matter. mips-opc.c has the
> following
> comment:
> /* jr.hb is officially MIPS{32,64}R2, but it works on R1 as jr with
>the same hazard barrier effect. */
That it works on R1 is however not universally true, because as I recall
at least the original 4Kc CPU does trap with RI on non-zero hint values.
It may have qualified as a processor erratum though. I just did a quick
run-time check with a 5Kc CPU and that one does execute the JR.HB encoding
just fine. I don't have a specimen of 4Kc that I could readily use, even
though I do believe I have a 4Kc module along with an Algorithmics board
that could use it and which could possibly run NetBSD (I haven't checked).
NB the semantics claim is even less true, because there is no hazard
barrier effect with the R1 JR or JALR instructions ever, and for example
the 4Kc does require to have any hazards resolved by placing a suitable
number of intervening instructions (which do not have to be SSNOP however
as the 4Kc is not superscalar). So a typical instruction hazard such as a
change of the ASID is requires 1 spacing instruction and 3 such for a data
access and an instruction fetch respectively affected by a change of the
ASID[1].
I don't know where the note in mips-opc.c originally came from and at
this point it cannot be verified. As it was typical at the time, the
change was posted with just a vague note referring a "mixed bag of opcode
table changes" as it was applied[2], so it does not help.
References:
[1] "MIPS32 4K Processor Core Family Software User's Manual", MIPS
Technologies, Inc., Document Number: MD00016, Revision 01.17,
September 25, 2002, Table 2-6 "Instruction Hazards", p. 28
[2] "MIPS opcode table update",
Maciej
RE: [PATCH] [MIPS] Hazard barrier return support
> -Original Message-
> From: Dragan Mladjenovic
> Sent: 17 August 2021 17:59
> To: 'Andrew Pinski'
> Cc: 'gcc-patches@gcc.gnu.org'
> Subject: RE: [PATCH] [MIPS] Hazard barrier return support
>
>
>
> > -Original Message-
> > From: Dragan Mladjenovic
> > Sent: 16 August 2021 22:40
> > To: 'Andrew Pinski'
> > Cc: gcc-patches@gcc.gnu.org
> > Subject: RE: [PATCH] [MIPS] Hazard barrier return support
> >
> >
> >
> > > -Original Message-
> > > From: Andrew Pinski [mailto:pins...@gmail.com]
> > > Sent: 16 August 2021 21:17
> > > To: Dragan Mladjenovic
> > > Cc: gcc-patches@gcc.gnu.org
> > > Subject: Re: [PATCH] [MIPS] Hazard barrier return support
> > >
> > > On Mon, Aug 16, 2021 at 7:43 AM Dragan Mladjenovic via Gcc-patches
> > > wrote:
> > > >
> > > > This patch allows a function to request clearing of all
> > > > instruction and execution hazards upon normal return via
> > > > __attribute__
> > > ((use_hazard_barrier_return)).
> > > >
> > > > 2017-04-25 Prachi Godbole
> > > >
> > > > gcc/
> > > > * config/mips/mips.h (machine_function): New variable
> > > > use_hazard_barrier_return_p.
> > > > * config/mips/mips.md (UNSPEC_JRHB): New unspec.
> > > > (mips_hb_return_internal): New insn pattern.
> > > > * config/mips/mips.c (mips_attribute_table): Add attribute
> > > > use_hazard_barrier_return.
> > > > (mips_use_hazard_barrier_return_p): New static function.
> > > > (mips_function_attr_inlinable_p): Likewise.
> > > > (mips_compute_frame_info): Set use_hazard_barrier_return_p.
> > > > Emit error for unsupported architecture choice.
> > > > (mips_function_ok_for_sibcall, mips_can_use_return_insn):
> > > > Return false for use_hazard_barrier_return.
> > > > (mips_expand_epilogue): Emit hazard barrier return.
> > > > * doc/extend.texi: Document use_hazard_barrier_return.
> > > >
> > > > gcc/testsuite/
> > > > * gcc.target/mips/hazard-barrier-return-attribute.c: New test.
> > > > ---
> > > > Rehash of original patch posted by Prachi with minimal changes.
> > > > Tested against mips-mti-elf with mips32r2/-EB and mips32r2/-EB/-
> > micromips.
> > > >
> > > > gcc/config/mips/mips.c| 58 +--
> > > > gcc/config/mips/mips.h| 3 +
> > > > gcc/config/mips/mips.md | 15 +
> > > > gcc/doc/extend.texi | 6 ++
> > > > .../mips/hazard-barrier-return-attribute.c| 20 +++
> > > > 5 files changed, 98 insertions(+), 4 deletions(-) create mode
> > > > 100644
> > > > gcc/testsuite/gcc.target/mips/hazard-barrier-return-attribute.c
> > > >
> > > > diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c index
> > > > 89d1be6cea6..6ce12fce52e 100644
> > > > --- a/gcc/config/mips/mips.c
> > > > +++ b/gcc/config/mips/mips.c
> > > > @@ -630,6 +630,7 @@ static const struct attribute_spec
> > > mips_attribute_table[] = {
> > > > mips_handle_use_shadow_register_set_attr, NULL },
> > > >{ "keep_interrupts_masked", 0, 0, false, true, true, false, NULL,
> NULL },
> > > >{ "use_debug_exception_return", 0, 0, false, true, true, false,
> > > > NULL, NULL },
> > > > + { "use_hazard_barrier_return", 0, 0, true, false, false, false,
> > > > + NULL, NULL },
> > > >{ NULL, 0, 0, false, false, false, false, NULL, NULL }
> > > > };
> > > >
> > > > @@ -1309,6 +1310,16 @@ mips_use_debug_exception_return_p (tree
> > > type)
> > > >TYPE_ATTRIBUTES (type)) != NULL; }
> > > >
> > > > +/* Check if the attribute to use hazard barrier return is set for
> > > > + the function declaration DECL. */
> > > > +
> > > > +static bool
> > > > +mips_use_hazard_barrier_return_p (const_tree decl) {
> > > > + return lookup_attribute ("use_hazard_barrier_return",
> > > > + DECL_ATTRIBUTES (decl)) != NULL; }
> > > > +
> > > >
RE: [PATCH] [MIPS] Hazard barrier return support
> -Original Message-
> From: Dragan Mladjenovic
> Sent: 16 August 2021 22:40
> To: 'Andrew Pinski'
> Cc: gcc-patches@gcc.gnu.org
> Subject: RE: [PATCH] [MIPS] Hazard barrier return support
>
>
>
> > -Original Message-
> > From: Andrew Pinski [mailto:pins...@gmail.com]
> > Sent: 16 August 2021 21:17
> > To: Dragan Mladjenovic
> > Cc: gcc-patches@gcc.gnu.org
> > Subject: Re: [PATCH] [MIPS] Hazard barrier return support
> >
> > On Mon, Aug 16, 2021 at 7:43 AM Dragan Mladjenovic via Gcc-patches
> > wrote:
> > >
> > > This patch allows a function to request clearing of all instruction
> > > and execution hazards upon normal return via __attribute__
> > ((use_hazard_barrier_return)).
> > >
> > > 2017-04-25 Prachi Godbole
> > >
> > > gcc/
> > > * config/mips/mips.h (machine_function): New variable
> > > use_hazard_barrier_return_p.
> > > * config/mips/mips.md (UNSPEC_JRHB): New unspec.
> > > (mips_hb_return_internal): New insn pattern.
> > > * config/mips/mips.c (mips_attribute_table): Add attribute
> > > use_hazard_barrier_return.
> > > (mips_use_hazard_barrier_return_p): New static function.
> > > (mips_function_attr_inlinable_p): Likewise.
> > > (mips_compute_frame_info): Set use_hazard_barrier_return_p.
> > > Emit error for unsupported architecture choice.
> > > (mips_function_ok_for_sibcall, mips_can_use_return_insn):
> > > Return false for use_hazard_barrier_return.
> > > (mips_expand_epilogue): Emit hazard barrier return.
> > > * doc/extend.texi: Document use_hazard_barrier_return.
> > >
> > > gcc/testsuite/
> > > * gcc.target/mips/hazard-barrier-return-attribute.c: New test.
> > > ---
> > > Rehash of original patch posted by Prachi with minimal changes.
> > > Tested against mips-mti-elf with mips32r2/-EB and mips32r2/-EB/-
> micromips.
> > >
> > > gcc/config/mips/mips.c| 58 +--
> > > gcc/config/mips/mips.h| 3 +
> > > gcc/config/mips/mips.md | 15 +
> > > gcc/doc/extend.texi | 6 ++
> > > .../mips/hazard-barrier-return-attribute.c| 20 +++
> > > 5 files changed, 98 insertions(+), 4 deletions(-) create mode
> > > 100644
> > > gcc/testsuite/gcc.target/mips/hazard-barrier-return-attribute.c
> > >
> > > diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c index
> > > 89d1be6cea6..6ce12fce52e 100644
> > > --- a/gcc/config/mips/mips.c
> > > +++ b/gcc/config/mips/mips.c
> > > @@ -630,6 +630,7 @@ static const struct attribute_spec
> > mips_attribute_table[] = {
> > > mips_handle_use_shadow_register_set_attr, NULL },
> > >{ "keep_interrupts_masked", 0, 0, false, true, true, false, NULL,
> > > NULL },
> > >{ "use_debug_exception_return", 0, 0, false, true, true, false,
> > > NULL, NULL },
> > > + { "use_hazard_barrier_return", 0, 0, true, false, false, false,
> > > + NULL, NULL },
> > >{ NULL, 0, 0, false, false, false, false, NULL, NULL }
> > > };
> > >
> > > @@ -1309,6 +1310,16 @@ mips_use_debug_exception_return_p (tree
> > type)
> > >TYPE_ATTRIBUTES (type)) != NULL; }
> > >
> > > +/* Check if the attribute to use hazard barrier return is set for
> > > + the function declaration DECL. */
> > > +
> > > +static bool
> > > +mips_use_hazard_barrier_return_p (const_tree decl) {
> > > + return lookup_attribute ("use_hazard_barrier_return",
> > > + DECL_ATTRIBUTES (decl)) != NULL; }
> > > +
> > > /* Return the set of compression modes that are explicitly required
> > > by the attributes in ATTRIBUTES. */
> > >
> > > @@ -1494,6 +1505,19 @@ mips_can_inline_p (tree caller, tree callee)
> > >return default_target_can_inline_p (caller, callee); }
> > >
> > > +/* Implement TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P.
> > > +
> > > + A function requesting clearing of all instruction and execution
> > > hazards
> > > + before returning cannot be inlined - thereby not clearing any hazards.
> > > + All our other function attributes are relate
RE: [PATCH] [MIPS] Hazard barrier return support
> -Original Message-
> From: Andrew Pinski [mailto:pins...@gmail.com]
> Sent: 16 August 2021 21:17
> To: Dragan Mladjenovic
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] [MIPS] Hazard barrier return support
>
> On Mon, Aug 16, 2021 at 7:43 AM Dragan Mladjenovic via Gcc-patches patc...@gcc.gnu.org> wrote:
> >
> > This patch allows a function to request clearing of all instruction
> > and execution hazards upon normal return via __attribute__
> ((use_hazard_barrier_return)).
> >
> > 2017-04-25 Prachi Godbole
> >
> > gcc/
> > * config/mips/mips.h (machine_function): New variable
> > use_hazard_barrier_return_p.
> > * config/mips/mips.md (UNSPEC_JRHB): New unspec.
> > (mips_hb_return_internal): New insn pattern.
> > * config/mips/mips.c (mips_attribute_table): Add attribute
> > use_hazard_barrier_return.
> > (mips_use_hazard_barrier_return_p): New static function.
> > (mips_function_attr_inlinable_p): Likewise.
> > (mips_compute_frame_info): Set use_hazard_barrier_return_p.
> > Emit error for unsupported architecture choice.
> > (mips_function_ok_for_sibcall, mips_can_use_return_insn):
> > Return false for use_hazard_barrier_return.
> > (mips_expand_epilogue): Emit hazard barrier return.
> > * doc/extend.texi: Document use_hazard_barrier_return.
> >
> > gcc/testsuite/
> > * gcc.target/mips/hazard-barrier-return-attribute.c: New test.
> > ---
> > Rehash of original patch posted by Prachi with minimal changes. Tested
> > against mips-mti-elf with mips32r2/-EB and mips32r2/-EB/-micromips.
> >
> > gcc/config/mips/mips.c| 58 +--
> > gcc/config/mips/mips.h| 3 +
> > gcc/config/mips/mips.md | 15 +
> > gcc/doc/extend.texi | 6 ++
> > .../mips/hazard-barrier-return-attribute.c| 20 +++
> > 5 files changed, 98 insertions(+), 4 deletions(-) create mode 100644
> > gcc/testsuite/gcc.target/mips/hazard-barrier-return-attribute.c
> >
> > diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c index
> > 89d1be6cea6..6ce12fce52e 100644
> > --- a/gcc/config/mips/mips.c
> > +++ b/gcc/config/mips/mips.c
> > @@ -630,6 +630,7 @@ static const struct attribute_spec
> mips_attribute_table[] = {
> > mips_handle_use_shadow_register_set_attr, NULL },
> >{ "keep_interrupts_masked", 0, 0, false, true, true, false, NULL, NULL
> > },
> >{ "use_debug_exception_return", 0, 0, false, true, true, false,
> > NULL, NULL },
> > + { "use_hazard_barrier_return", 0, 0, true, false, false, false,
> > + NULL, NULL },
> >{ NULL, 0, 0, false, false, false, false, NULL, NULL }
> > };
> >
> > @@ -1309,6 +1310,16 @@ mips_use_debug_exception_return_p (tree
> type)
> >TYPE_ATTRIBUTES (type)) != NULL; }
> >
> > +/* Check if the attribute to use hazard barrier return is set for
> > + the function declaration DECL. */
> > +
> > +static bool
> > +mips_use_hazard_barrier_return_p (const_tree decl) {
> > + return lookup_attribute ("use_hazard_barrier_return",
> > + DECL_ATTRIBUTES (decl)) != NULL; }
> > +
> > /* Return the set of compression modes that are explicitly required
> > by the attributes in ATTRIBUTES. */
> >
> > @@ -1494,6 +1505,19 @@ mips_can_inline_p (tree caller, tree callee)
> >return default_target_can_inline_p (caller, callee); }
> >
> > +/* Implement TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P.
> > +
> > + A function requesting clearing of all instruction and execution hazards
> > + before returning cannot be inlined - thereby not clearing any hazards.
> > + All our other function attributes are related to how out-of-line copies
> > + should be compiled or called. They don't in themselves prevent
> > + inlining. */
> > +
> > +static bool
> > +mips_function_attr_inlinable_p (const_tree decl) {
> > + return !mips_use_hazard_barrier_return_p (decl); }
> > +
> > /* Handle an "interrupt" attribute with an optional argument. */
> >
> > static tree
> > @@ -7921,6 +7945,11 @@ mips_function_ok_for_sibcall (tree decl, tree
> exp ATTRIBUTE_UNUSED)
> >&& !targetm.binds_local_p (decl))
> > return false;
> >
> > + /* Can't generate sibling calls if returni
Re: [PATCH] [MIPS] Hazard barrier return support
On Mon, Aug 16, 2021 at 7:43 AM Dragan Mladjenovic via Gcc-patches
wrote:
>
> This patch allows a function to request clearing of all instruction and
> execution
> hazards upon normal return via __attribute__ ((use_hazard_barrier_return)).
>
> 2017-04-25 Prachi Godbole
>
> gcc/
> * config/mips/mips.h (machine_function): New variable
> use_hazard_barrier_return_p.
> * config/mips/mips.md (UNSPEC_JRHB): New unspec.
> (mips_hb_return_internal): New insn pattern.
> * config/mips/mips.c (mips_attribute_table): Add attribute
> use_hazard_barrier_return.
> (mips_use_hazard_barrier_return_p): New static function.
> (mips_function_attr_inlinable_p): Likewise.
> (mips_compute_frame_info): Set use_hazard_barrier_return_p.
> Emit error for unsupported architecture choice.
> (mips_function_ok_for_sibcall, mips_can_use_return_insn):
> Return false for use_hazard_barrier_return.
> (mips_expand_epilogue): Emit hazard barrier return.
> * doc/extend.texi: Document use_hazard_barrier_return.
>
> gcc/testsuite/
> * gcc.target/mips/hazard-barrier-return-attribute.c: New test.
> ---
> Rehash of original patch posted by Prachi with minimal changes. Tested against
> mips-mti-elf with mips32r2/-EB and mips32r2/-EB/-micromips.
>
> gcc/config/mips/mips.c| 58 +--
> gcc/config/mips/mips.h| 3 +
> gcc/config/mips/mips.md | 15 +
> gcc/doc/extend.texi | 6 ++
> .../mips/hazard-barrier-return-attribute.c| 20 +++
> 5 files changed, 98 insertions(+), 4 deletions(-)
> create mode 100644
> gcc/testsuite/gcc.target/mips/hazard-barrier-return-attribute.c
>
> diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
> index 89d1be6cea6..6ce12fce52e 100644
> --- a/gcc/config/mips/mips.c
> +++ b/gcc/config/mips/mips.c
> @@ -630,6 +630,7 @@ static const struct attribute_spec mips_attribute_table[]
> = {
> mips_handle_use_shadow_register_set_attr, NULL },
>{ "keep_interrupts_masked", 0, 0, false, true, true, false, NULL, NULL },
>{ "use_debug_exception_return", 0, 0, false, true, true, false, NULL, NULL
> },
> + { "use_hazard_barrier_return", 0, 0, true, false, false, false, NULL, NULL
> },
>{ NULL, 0, 0, false, false, false, false, NULL, NULL }
> };
>
> @@ -1309,6 +1310,16 @@ mips_use_debug_exception_return_p (tree type)
>TYPE_ATTRIBUTES (type)) != NULL;
> }
>
> +/* Check if the attribute to use hazard barrier return is set for
> + the function declaration DECL. */
> +
> +static bool
> +mips_use_hazard_barrier_return_p (const_tree decl)
> +{
> + return lookup_attribute ("use_hazard_barrier_return",
> + DECL_ATTRIBUTES (decl)) != NULL;
> +}
> +
> /* Return the set of compression modes that are explicitly required
> by the attributes in ATTRIBUTES. */
>
> @@ -1494,6 +1505,19 @@ mips_can_inline_p (tree caller, tree callee)
>return default_target_can_inline_p (caller, callee);
> }
>
> +/* Implement TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P.
> +
> + A function requesting clearing of all instruction and execution hazards
> + before returning cannot be inlined - thereby not clearing any hazards.
> + All our other function attributes are related to how out-of-line copies
> + should be compiled or called. They don't in themselves prevent inlining.
> */
> +
> +static bool
> +mips_function_attr_inlinable_p (const_tree decl)
> +{
> + return !mips_use_hazard_barrier_return_p (decl);
> +}
> +
> /* Handle an "interrupt" attribute with an optional argument. */
>
> static tree
> @@ -7921,6 +7945,11 @@ mips_function_ok_for_sibcall (tree decl, tree exp
> ATTRIBUTE_UNUSED)
>&& !targetm.binds_local_p (decl))
> return false;
>
> + /* Can't generate sibling calls if returning from current function using
> + hazard barrier return. */
> + if (mips_use_hazard_barrier_return_p (current_function_decl))
> +return false;
> +
>/* Otherwise OK. */
>return true;
> }
> @@ -11008,6 +11037,17 @@ mips_compute_frame_info (void)
> }
> }
>
> + /* Determine whether to use hazard barrier return or not. */
> + if (mips_use_hazard_barrier_return_p (current_function_decl))
> +{
> + if (mips_isa_rev < 2)
> + error ("hazard barrier returns require a MIPS32r2 processor or
> greater");
Just a small nit, is MIPS64r2 ok too? Also did you did you test it
for MIPS64 too? I still partly care about MIPS64.
Thanks,
Andrew
> + else if (TARGET_MIPS16)
> + error ("hazard barrier returns are not supported for MIPS16
> functions");
> + else
> + cfun->machine->use_hazard_barrier_return_p = true;
> +}
> +
>frame = >machine->frame;
>memset (frame, 0, sizeof (*frame));
>size = get_frame_size ();
> @@ -12671,7 +12711,8 @@
[PATCH] [MIPS] Hazard barrier return support
This patch allows a function to request clearing of all instruction and
execution
hazards upon normal return via __attribute__ ((use_hazard_barrier_return)).
2017-04-25 Prachi Godbole
gcc/
* config/mips/mips.h (machine_function): New variable
use_hazard_barrier_return_p.
* config/mips/mips.md (UNSPEC_JRHB): New unspec.
(mips_hb_return_internal): New insn pattern.
* config/mips/mips.c (mips_attribute_table): Add attribute
use_hazard_barrier_return.
(mips_use_hazard_barrier_return_p): New static function.
(mips_function_attr_inlinable_p): Likewise.
(mips_compute_frame_info): Set use_hazard_barrier_return_p.
Emit error for unsupported architecture choice.
(mips_function_ok_for_sibcall, mips_can_use_return_insn):
Return false for use_hazard_barrier_return.
(mips_expand_epilogue): Emit hazard barrier return.
* doc/extend.texi: Document use_hazard_barrier_return.
gcc/testsuite/
* gcc.target/mips/hazard-barrier-return-attribute.c: New test.
---
Rehash of original patch posted by Prachi with minimal changes. Tested against
mips-mti-elf with mips32r2/-EB and mips32r2/-EB/-micromips.
gcc/config/mips/mips.c| 58 +--
gcc/config/mips/mips.h| 3 +
gcc/config/mips/mips.md | 15 +
gcc/doc/extend.texi | 6 ++
.../mips/hazard-barrier-return-attribute.c| 20 +++
5 files changed, 98 insertions(+), 4 deletions(-)
create mode 100644
gcc/testsuite/gcc.target/mips/hazard-barrier-return-attribute.c
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 89d1be6cea6..6ce12fce52e 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -630,6 +630,7 @@ static const struct attribute_spec mips_attribute_table[] =
{
mips_handle_use_shadow_register_set_attr, NULL },
{ "keep_interrupts_masked", 0, 0, false, true, true, false, NULL, NULL },
{ "use_debug_exception_return", 0, 0, false, true, true, false, NULL, NULL },
+ { "use_hazard_barrier_return", 0, 0, true, false, false, false, NULL, NULL },
{ NULL, 0, 0, false, false, false, false, NULL, NULL }
};
@@ -1309,6 +1310,16 @@ mips_use_debug_exception_return_p (tree type)
TYPE_ATTRIBUTES (type)) != NULL;
}
+/* Check if the attribute to use hazard barrier return is set for
+ the function declaration DECL. */
+
+static bool
+mips_use_hazard_barrier_return_p (const_tree decl)
+{
+ return lookup_attribute ("use_hazard_barrier_return",
+ DECL_ATTRIBUTES (decl)) != NULL;
+}
+
/* Return the set of compression modes that are explicitly required
by the attributes in ATTRIBUTES. */
@@ -1494,6 +1505,19 @@ mips_can_inline_p (tree caller, tree callee)
return default_target_can_inline_p (caller, callee);
}
+/* Implement TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P.
+
+ A function requesting clearing of all instruction and execution hazards
+ before returning cannot be inlined - thereby not clearing any hazards.
+ All our other function attributes are related to how out-of-line copies
+ should be compiled or called. They don't in themselves prevent inlining.
*/
+
+static bool
+mips_function_attr_inlinable_p (const_tree decl)
+{
+ return !mips_use_hazard_barrier_return_p (decl);
+}
+
/* Handle an "interrupt" attribute with an optional argument. */
static tree
@@ -7921,6 +7945,11 @@ mips_function_ok_for_sibcall (tree decl, tree exp
ATTRIBUTE_UNUSED)
&& !targetm.binds_local_p (decl))
return false;
+ /* Can't generate sibling calls if returning from current function using
+ hazard barrier return. */
+ if (mips_use_hazard_barrier_return_p (current_function_decl))
+return false;
+
/* Otherwise OK. */
return true;
}
@@ -11008,6 +11037,17 @@ mips_compute_frame_info (void)
}
}
+ /* Determine whether to use hazard barrier return or not. */
+ if (mips_use_hazard_barrier_return_p (current_function_decl))
+{
+ if (mips_isa_rev < 2)
+ error ("hazard barrier returns require a MIPS32r2 processor or
greater");
+ else if (TARGET_MIPS16)
+ error ("hazard barrier returns are not supported for MIPS16 functions");
+ else
+ cfun->machine->use_hazard_barrier_return_p = true;
+}
+
frame = >machine->frame;
memset (frame, 0, sizeof (*frame));
size = get_frame_size ();
@@ -12671,7 +12711,8 @@ mips_expand_epilogue (bool sibcall_p)
&& !crtl->calls_eh_return
&& !sibcall_p
&& step2 > 0
- && mips_unsigned_immediate_p (step2, 5, 2))
+ && mips_unsigned_immediate_p (step2, 5, 2)
+ && !cfun->machine->use_hazard_barrier_return_p)
use_jraddiusp_p = true;
else
/* Deallocate the final bit of the frame. */
@@ -12712,6 +12753,11 @@ mips_expand_epilogue
