[PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Szabolcs Nagy]

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v2:
- use aarch64_simd_decl_p to check for aarch64_vector_pcs.
- emit the .variant_pcs directive even for local functions.
- don't require .variant_pcs asm support in compile only tests.
- add weakref tests.

A dynamic linker with lazy binding support may need to handle vector PCS
function symbols specially, so an ELF symbol table marking was
introduced for such symbols.

Function symbol references and definitions that follow the vector PCS
are marked in the generated assembly with .variant_pcs and then the
STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
file.  The marking is propagated to the dynamic symbol table by the
static linker so a dynamic linker can handle such symbols specially.

For this to work, the assembler, the static linker and the dynamic
linker has to be updated on a system.  Old assembler does not support
the new .variant_pcs directive, so a toolchain with old binutils won't
be able to compile code that references vector PCS symbols.

gcc/ChangeLog:

2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
	(aarch64_asm_output_external): Declare.
	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
	(aarch64_asm_output_alias): New.
	(aarch64_asm_output_external): New.
	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
	(ASM_OUTPUT_EXTERNAL): Define.

gcc/testsuite/ChangeLog:

2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* gcc.target/aarch64/pcs_attribute-2.c: New test.
	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
	New.

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diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index a0723266f22..19e9767c792 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -427,6 +427,8 @@ bool aarch64_is_long_call_p (rtx);
 bool aarch64_is_noplt_call_p (rtx);
 bool aarch64_label_mentioned_p (rtx);
 void aarch64_declare_function_name (FILE *, const char*, tree);
+void aarch64_asm_output_alias (FILE *, const tree, const tree);
+void aarch64_asm_output_external (FILE *, const tree, const char*);
 bool aarch64_legitimate_pic_operand_p (rtx);
 bool aarch64_mask_and_shift_for_ubfiz_p (scalar_int_mode, rtx, rtx);
 bool aarch64_masks_and_shift_for_bfi_p (scalar_int_mode, unsigned HOST_WIDE_INT,
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 83453d03095..16e534b0772 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -15276,6 +15276,19 @@ aarch64_asm_preferred_eh_data_format (int code ATTRIBUTE_UNUSED, int global)
    return (global ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | type;
 }
 
+/* Output .variant_pcs for aarch64_vector_pcs function symbols.  */
+
+static void
+aarch64_asm_output_variant_pcs (FILE *stream, const tree decl, const char* name)
+{
+  if (aarch64_simd_decl_p (decl))
+    {
+      fprintf (stream, "\t.variant_pcs\t");
+      assemble_name (stream, name);
+      fprintf (stream, "\n");
+    }
+}
+
 /* The last .arch and .tune assembly strings that we printed.  */
 static std::string aarch64_last_printed_arch_string;
 static std::string aarch64_last_printed_tune_string;
@@ -15325,11 +15338,33 @@ aarch64_declare_function_name (FILE *stream, const char* name,
       aarch64_last_printed_tune_string = this_tune->name;
     }
 
+  aarch64_asm_output_variant_pcs (stream, fndecl, name);
+
   /* Don't forget the type directive for ELF.  */
   ASM_OUTPUT_TYPE_DIRECTIVE (stream, name, "function");
   ASM_OUTPUT_LABEL (stream, name);
 }
 
+/* Implement ASM_OUTPUT_DEF_FROM_DECLS.  Output .variant_pcs for aliases.  */
+
+void
+aarch64_asm_output_alias (FILE *stream, const tree decl, const tree target)
+{
+  const char *name = XSTR (XEXP (DECL_RTL (decl), 0), 0);
+  const char *value = IDENTIFIER_POINTER (target);
+  aarch64_asm_output_variant_pcs (stream, decl, name);
+  ASM_OUTPUT_DEF (stream, name, value);
+}
+
+/* Implement ASM_OUTPUT_EXTERNAL.  Output .variant_pcs for undefined
+   function symbol references.  */
+
+void
+aarch64_asm_output_external (FILE *stream, const tree decl, const char* name)
+{
+  aarch64_asm_output_variant_pcs (stream, decl, name);
+}
+
 /* Implements TARGET_ASM_FILE_START.  Output the assembly header.  */
 
 static void
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index be6981889ab..f0f50e081ac 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -512,6 +512,15 @@ extern unsigned aarch64_architecture_version;
 #define ASM_DECLARE_FUNCTION_NAME(STR, NAME, DECL)	\
   aarch64_declare_function_name (STR, NAME, DECL)
 
+/* Output assembly strings for alias definition.  */
+#define ASM_OUTPUT_DEF_FROM_DECLS(STR, DECL, TARGET) \
+  aarch64_asm_output_alias (STR, DECL, TARGET)
+
+/* Output assembly strings for undefined extern symbols.  */
+#undef ASM_OUTPUT_EXTERNAL
+#define ASM_OUTPUT_EXTERNAL(STR, DECL, NAME) \
+  aarch64_asm_output_external (STR, DECL, NAME)
+
 /* For EH returns X4 contains the stack adjustment.  */
 #define EH_RETURN_STACKADJ_RTX	gen_rtx_REG (Pmode, R4_REGNUM)
 #define EH_RETURN_HANDLER_RTX  aarch64_eh_return_handler_rtx ()
diff --git a/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c
new file mode 100644
index 00000000000..21fdc9c6eba
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c
@@ -0,0 +1,114 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target aarch64_variant_pcs } */
+
+/* Test that .variant_pcs is emitted for vector PCS symbol references.  */
+
+#define ATTR __attribute__ ((aarch64_vector_pcs))
+
+void f_undef_basepcs (void);
+
+void f_def_basepcs (void)
+{
+}
+
+ATTR void f_undef_vpcs (void);
+
+ATTR void f_def_vpcs (void)
+{
+}
+
+__attribute__ ((alias ("f_def_vpcs")))
+ATTR void f_alias_vpcs (void);
+
+__attribute__ ((weak, alias ("f_def_vpcs")))
+ATTR void f_weak_alias_vpcs (void);
+
+__attribute__ ((weak))
+ATTR void f_weak_undef_vpcs (void);
+
+__attribute__ ((visibility ("protected")))
+ATTR void f_protected_vpcs (void)
+{
+}
+
+__attribute__ ((visibility ("hidden")))
+ATTR void f_hidden_vpcs (void)
+{
+}
+
+ATTR static void f_local_vpcs (void)
+{
+}
+
+__attribute__((weakref ("f_undef_vpcs")))
+ATTR static void f_local_weakref_undef_vpcs (void);
+
+__attribute__((weakref ("f_hidden_vpcs")))
+ATTR static void f_local_weakref_def_vpcs (void);
+
+ATTR void bar_undef_vpcs (void) __asm__ ("f_undef_renamed_vpcs");
+
+ATTR void bar_def_vpcs (void) __asm__ ("f_def_renamed_vpcs");
+ATTR void bar_def_vpcs (void)
+{
+}
+
+static void (*f_ifunc_resolver ()) (void)
+{
+  return (void (*)(void))f_local_vpcs;
+}
+
+__attribute__ ((ifunc ("f_ifunc_resolver")))
+ATTR void f_ifunc_vpcs (void);
+
+__attribute__ ((visibility ("hidden")))
+__attribute__ ((ifunc ("f_ifunc_resolver")))
+ATTR void f_hidden_ifunc_vpcs (void);
+
+__attribute__ ((ifunc ("f_ifunc_resolver")))
+ATTR static void f_local_ifunc_vpcs (void);
+
+void (*refs_basepcs[]) (void) = {
+	f_undef_basepcs,
+	f_def_basepcs,
+};
+
+void (*ATTR refs_vpcs[]) (void) = {
+	f_undef_vpcs,
+	f_def_vpcs,
+	f_alias_vpcs,
+	f_weak_alias_vpcs,
+	f_weak_undef_vpcs,
+	f_protected_vpcs,
+	f_hidden_vpcs,
+	f_local_vpcs,
+	f_local_weakref_undef_vpcs,
+	f_local_weakref_def_vpcs,
+	bar_undef_vpcs,
+	bar_def_vpcs,
+	f_ifunc_vpcs,
+	f_hidden_ifunc_vpcs,
+	f_local_ifunc_vpcs,
+};
+
+/* Note: hidden and local symbols don't need .variant_pcs, but gcc generates
+   it, so we check them here.  An undefined weakref does not show up in the
+   symbol table, only the target symbol, so it does not need .variant_pcs.  */
+
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_undef_basepcs} } } */
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_def_basepcs} } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_undef_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_def_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_alias_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_weak_alias_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_weak_undef_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_protected_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_hidden_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_vpcs} 1 } } */
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_local_weakref_undef_vpcs} } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_weakref_def_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_undef_renamed_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_def_renamed_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_ifunc_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_hidden_ifunc_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_ifunc_vpcs} 1 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
index e399690f364..80ebd955e10 100644
--- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
+++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
@@ -1,4 +1,5 @@
 /* dg-do run */
+/* { dg-require-effective-target aarch64_variant_pcs } */
 /* { dg-additional-options "-std=c99" }  */
 
 
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 4bcf1a1c8f7..9fb05fc38ed 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -8591,6 +8591,17 @@ proc check_effective_target_aarch64_large { } {
     }
 }
 
+# Return 1 if the assembler accepts the aarch64 .variant_pcs directive.
+
+proc check_effective_target_aarch64_variant_pcs { } {
+    if { [istarget aarch64*-*-*] } {
+	return [check_no_compiler_messages aarch64_variant_pcs object {
+	    __asm__ (".variant_pcs foo");
+	}]
+    } else {
+	return 0
+    }
+}
 
 # Return 1 if this is a reduced AVR Tiny core.  Such cores have different
 # register set, instruction set, addressing capabilities and ABI.

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Richard Sandiford]

Szabolcs Nagy <Szabolcs.Nagy@arm.com> writes:
> v2:
> - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
> - emit the .variant_pcs directive even for local functions.
> - don't require .variant_pcs asm support in compile only tests.
> - add weakref tests.
>
> A dynamic linker with lazy binding support may need to handle vector PCS
> function symbols specially, so an ELF symbol table marking was
> introduced for such symbols.
>
> Function symbol references and definitions that follow the vector PCS
> are marked in the generated assembly with .variant_pcs and then the
> STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
> file.  The marking is propagated to the dynamic symbol table by the
> static linker so a dynamic linker can handle such symbols specially.
>
> For this to work, the assembler, the static linker and the dynamic
> linker has to be updated on a system.  Old assembler does not support
> the new .variant_pcs directive, so a toolchain with old binutils won't
> be able to compile code that references vector PCS symbols.
>
> gcc/ChangeLog:
>
> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>
> 	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
> 	(aarch64_asm_output_external): Declare.
> 	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
> 	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
> 	(aarch64_asm_output_alias): New.
> 	(aarch64_asm_output_external): New.
> 	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
> 	(ASM_OUTPUT_EXTERNAL): Define.
>
> gcc/testsuite/ChangeLog:
>
> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>
> 	* gcc.target/aarch64/pcs_attribute-2.c: New test.
> 	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
> 	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
> 	New.

LGTM, but an AArch64 maintainer will need to approve.

> diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> index e399690f364..80ebd955e10 100644
> --- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> +++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> @@ -1,4 +1,5 @@
>  /* dg-do run */
> +/* { dg-require-effective-target aarch64_variant_pcs } */
>  /* { dg-additional-options "-std=c99" }  */

Not your problem of course, but mind fixing the dg-do markup while
you're there?  It should be

/* { dg-do run } */

instead.  As things stand, the test only gets compiled, not run.

Thanks,
Richard

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[James Greenhalgh]

On Wed, May 29, 2019 at 11:00:46AM +0100, Richard Sandiford wrote:
> Szabolcs Nagy <Szabolcs.Nagy@arm.com> writes:
> > v2:
> > - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
> > - emit the .variant_pcs directive even for local functions.
> > - don't require .variant_pcs asm support in compile only tests.
> > - add weakref tests.
> >
> > A dynamic linker with lazy binding support may need to handle vector PCS
> > function symbols specially, so an ELF symbol table marking was
> > introduced for such symbols.
> >
> > Function symbol references and definitions that follow the vector PCS
> > are marked in the generated assembly with .variant_pcs and then the
> > STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
> > file.  The marking is propagated to the dynamic symbol table by the
> > static linker so a dynamic linker can handle such symbols specially.
> >
> > For this to work, the assembler, the static linker and the dynamic
> > linker has to be updated on a system.  Old assembler does not support
> > the new .variant_pcs directive, so a toolchain with old binutils won't
> > be able to compile code that references vector PCS symbols.
> >
> > gcc/ChangeLog:
> >
> > 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> >
> > 	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
> > 	(aarch64_asm_output_external): Declare.
> > 	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
> > 	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
> > 	(aarch64_asm_output_alias): New.
> > 	(aarch64_asm_output_external): New.
> > 	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
> > 	(ASM_OUTPUT_EXTERNAL): Define.
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> >
> > 	* gcc.target/aarch64/pcs_attribute-2.c: New test.
> > 	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
> > 	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
> > 	New.
> 
> LGTM, but an AArch64 maintainer will need to approve.

OK with Richard's change suggested below.

Thanks,
James

> 
> > diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > index e399690f364..80ebd955e10 100644
> > --- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > +++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > @@ -1,4 +1,5 @@
> >  /* dg-do run */
> > +/* { dg-require-effective-target aarch64_variant_pcs } */
> >  /* { dg-additional-options "-std=c99" }  */
> 
> Not your problem of course, but mind fixing the dg-do markup while
> you're there?  It should be
> 
> /* { dg-do run } */
> 
> instead.  As things stand, the test only gets compiled, not run.
> 
> Thanks,
> Richard

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Christophe Lyon]

On Mon, 3 Jun 2019 at 13:28, James Greenhalgh <james.greenhalgh@arm.com> wrote:
>
> On Wed, May 29, 2019 at 11:00:46AM +0100, Richard Sandiford wrote:
> > Szabolcs Nagy <Szabolcs.Nagy@arm.com> writes:
> > > v2:
> > > - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
> > > - emit the .variant_pcs directive even for local functions.
> > > - don't require .variant_pcs asm support in compile only tests.
> > > - add weakref tests.
> > >
> > > A dynamic linker with lazy binding support may need to handle vector PCS
> > > function symbols specially, so an ELF symbol table marking was
> > > introduced for such symbols.
> > >
> > > Function symbol references and definitions that follow the vector PCS
> > > are marked in the generated assembly with .variant_pcs and then the
> > > STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
> > > file.  The marking is propagated to the dynamic symbol table by the
> > > static linker so a dynamic linker can handle such symbols specially.
> > >
> > > For this to work, the assembler, the static linker and the dynamic
> > > linker has to be updated on a system.  Old assembler does not support
> > > the new .variant_pcs directive, so a toolchain with old binutils won't
> > > be able to compile code that references vector PCS symbols.
> > >
> > > gcc/ChangeLog:
> > >
> > > 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> > >
> > >     * config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
> > >     (aarch64_asm_output_external): Declare.
> > >     * config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
> > >     (aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
> > >     (aarch64_asm_output_alias): New.
> > >     (aarch64_asm_output_external): New.
> > >     * config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
> > >     (ASM_OUTPUT_EXTERNAL): Define.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> > >
> > >     * gcc.target/aarch64/pcs_attribute-2.c: New test.
> > >     * gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
> > >     * lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
> > >     New.
> >
> > LGTM, but an AArch64 maintainer will need to approve.
>
> OK with Richard's change suggested below.
>

Hi,

Since this patch was committed (r271869), I've noticed regressions on aarch64:
FAIL:    gcc.dg/visibility-14.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-15.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-16.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-17.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-18.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-19.c scan-hidden hidden[ \t_]*foo
FAIL:    gcc.dg/visibility-23.c scan-hidden hidden[ \t_]*foo

Didn't you see them when you tested the patch?

Thanks,

Christophe


> Thanks,
> James
>
> >
> > > diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > > index e399690f364..80ebd955e10 100644
> > > --- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > > +++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
> > > @@ -1,4 +1,5 @@
> > >  /* dg-do run */
> > > +/* { dg-require-effective-target aarch64_variant_pcs } */
> > >  /* { dg-additional-options "-std=c99" }  */
> >
> > Not your problem of course, but mind fixing the dg-do markup while
> > you're there?  It should be
> >
> > /* { dg-do run } */
> >
> > instead.  As things stand, the test only gets compiled, not run.
> >
> > Thanks,
> > Richard

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Szabolcs Nagy]

On 04/06/2019 13:21, Christophe Lyon wrote:
> On Mon, 3 Jun 2019 at 13:28, James Greenhalgh <james.greenhalgh@arm.com> wrote:
>>
>> On Wed, May 29, 2019 at 11:00:46AM +0100, Richard Sandiford wrote:
>>> Szabolcs Nagy <Szabolcs.Nagy@arm.com> writes:
>>>> v2:
>>>> - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
>>>> - emit the .variant_pcs directive even for local functions.
>>>> - don't require .variant_pcs asm support in compile only tests.
>>>> - add weakref tests.
>>>>
>>>> A dynamic linker with lazy binding support may need to handle vector PCS
>>>> function symbols specially, so an ELF symbol table marking was
>>>> introduced for such symbols.
>>>>
>>>> Function symbol references and definitions that follow the vector PCS
>>>> are marked in the generated assembly with .variant_pcs and then the
>>>> STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
>>>> file.  The marking is propagated to the dynamic symbol table by the
>>>> static linker so a dynamic linker can handle such symbols specially.
>>>>
>>>> For this to work, the assembler, the static linker and the dynamic
>>>> linker has to be updated on a system.  Old assembler does not support
>>>> the new .variant_pcs directive, so a toolchain with old binutils won't
>>>> be able to compile code that references vector PCS symbols.
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>>>>
>>>>     * config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
>>>>     (aarch64_asm_output_external): Declare.
>>>>     * config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
>>>>     (aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
>>>>     (aarch64_asm_output_alias): New.
>>>>     (aarch64_asm_output_external): New.
>>>>     * config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
>>>>     (ASM_OUTPUT_EXTERNAL): Define.
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>>>>
>>>>     * gcc.target/aarch64/pcs_attribute-2.c: New test.
>>>>     * gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
>>>>     * lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
>>>>     New.
>>>
>>> LGTM, but an AArch64 maintainer will need to approve.
>>
>> OK with Richard's change suggested below.
>>
> 
> Hi,
> 
> Since this patch was committed (r271869), I've noticed regressions on aarch64:
> FAIL:    gcc.dg/visibility-14.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-15.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-16.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-17.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-18.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-19.c scan-hidden hidden[ \t_]*foo
> FAIL:    gcc.dg/visibility-23.c scan-hidden hidden[ \t_]*foo
> 
> Didn't you see them when you tested the patch?

sorry i missed these.

i broke asm visibility declarations for extern symbols,
i will have a fix soon.

> 
> Thanks,
> 
> Christophe
> 
> 
>> Thanks,
>> James
>>
>>>
>>>> diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
>>>> index e399690f364..80ebd955e10 100644
>>>> --- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
>>>> +++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
>>>> @@ -1,4 +1,5 @@
>>>>  /* dg-do run */
>>>> +/* { dg-require-effective-target aarch64_variant_pcs } */
>>>>  /* { dg-additional-options "-std=c99" }  */
>>>
>>> Not your problem of course, but mind fixing the dg-do markup while
>>> you're there?  It should be
>>>
>>> /* { dg-do run } */
>>>
>>> instead.  As things stand, the test only gets compiled, not run.
>>>
>>> Thanks,
>>> Richard

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Szabolcs Nagy]

[-- Attachment #1: Type: text/plain, Size: 2025 bytes --]

On 28/05/2019 16:01, Szabolcs Nagy wrote:
> v2:
> - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
> - emit the .variant_pcs directive even for local functions.
> - don't require .variant_pcs asm support in compile only tests.
> - add weakref tests.
> 
> A dynamic linker with lazy binding support may need to handle vector PCS
> function symbols specially, so an ELF symbol table marking was
> introduced for such symbols.
> 
> Function symbol references and definitions that follow the vector PCS
> are marked in the generated assembly with .variant_pcs and then the
> STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
> file.  The marking is propagated to the dynamic symbol table by the
> static linker so a dynamic linker can handle such symbols specially.
> 
> For this to work, the assembler, the static linker and the dynamic
> linker has to be updated on a system.  Old assembler does not support
> the new .variant_pcs directive, so a toolchain with old binutils won't
> be able to compile code that references vector PCS symbols.
> 
> gcc/ChangeLog:
> 
> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
> 	(aarch64_asm_output_external): Declare.
> 	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
> 	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
> 	(aarch64_asm_output_alias): New.
> 	(aarch64_asm_output_external): New.
> 	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
> 	(ASM_OUTPUT_EXTERNAL): Define.
> 
> gcc/testsuite/ChangeLog:
> 
> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* gcc.target/aarch64/pcs_attribute-2.c: New test.
> 	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
> 	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
> 	New.
> 

i'd like to backport this and follow up fixes to the gcc-9 branch,
see attached patch.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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From 54f408f666f7224563d2a1ff10eda6ab4d8864b1 Mon Sep 17 00:00:00 2001
From: nsz <nsz@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 3 Jun 2019 13:50:53 +0000
Subject: [PATCH] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol
 references

Backport r271869
Backport r271913
Backport r272414

A dynamic linker with lazy binding support may need to handle vector PCS
function symbols specially, so an ELF symbol table marking was
introduced for such symbols.

Function symbol references and definitions that follow the vector PCS
are marked in the generated assembly with .variant_pcs and then the
STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
file.  The marking is propagated to the dynamic symbol table by the
static linker so a dynamic linker can handle such symbols specially.

For this to work, the assembler, the static linker and the dynamic
linker has to be updated on a system.  Old assembler does not support
the new .variant_pcs directive, so a toolchain with old binutils won't
be able to compile code that references vector PCS symbols.

gcc/ChangeLog:

	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
	(aarch64_asm_output_external): Declare.
	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
	(aarch64_asm_output_alias): New.
	(aarch64_asm_output_external): New.
	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
	(ASM_OUTPUT_EXTERNAL): Define.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/pcs_attribute-2.c: New test.
	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
	New.

gcc/ChangeLog:

	* config/aarch64/aarch64-protos.h (aarch64_asm_output_external): Remove
	const.
	* config/aarch64/aarch64.c (aarch64_asm_output_external): Call
	default_elf_asm_output_external.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/pcs_attribute-2.c: Remove ifunc usage.
	* gcc.target/aarch64/pcs_attribute-3.c: New test.
---
 gcc/ChangeLog                                 | 21 +++++
 gcc/config/aarch64/aarch64-protos.h           |  2 +
 gcc/config/aarch64/aarch64.c                  | 36 +++++++
 gcc/config/aarch64/aarch64.h                  |  9 ++
 gcc/testsuite/ChangeLog                       | 15 +++
 .../gcc.target/aarch64/pcs_attribute-2.c      | 93 +++++++++++++++++++
 .../gcc.target/aarch64/pcs_attribute-3.c      | 58 ++++++++++++
 .../gcc.target/aarch64/torture/simd-abi-4.c   |  3 +-
 gcc/testsuite/lib/target-supports.exp         | 11 +++
 9 files changed, 247 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c
 create mode 100644 gcc/testsuite/gcc.target/aarch64/pcs_attribute-3.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 82010817b6a..c0ec9df3db1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,24 @@
+2019-07-05  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	Backport from mainline
+	2019-06-03  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
+	(aarch64_asm_output_external): Declare.
+	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
+	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
+	(aarch64_asm_output_alias): New.
+	(aarch64_asm_output_external): New.
+	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
+	(ASM_OUTPUT_EXTERNAL): Define.
+
+	2019-06-04  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* config/aarch64/aarch64-protos.h (aarch64_asm_output_external): Remove
+	const.
+	* config/aarch64/aarch64.c (aarch64_asm_output_external): Call
+	default_elf_asm_output_external.
+
 2019-07-04  Martin Liska  <mliska@suse.cz>
 
 	Backport from mainline
diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index b6c0d0a8eb6..c083cad5327 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -427,6 +427,8 @@ bool aarch64_is_long_call_p (rtx);
 bool aarch64_is_noplt_call_p (rtx);
 bool aarch64_label_mentioned_p (rtx);
 void aarch64_declare_function_name (FILE *, const char*, tree);
+void aarch64_asm_output_alias (FILE *, const tree, const tree);
+void aarch64_asm_output_external (FILE *, tree, const char*);
 bool aarch64_legitimate_pic_operand_p (rtx);
 bool aarch64_mask_and_shift_for_ubfiz_p (scalar_int_mode, rtx, rtx);
 bool aarch64_masks_and_shift_for_bfi_p (scalar_int_mode, unsigned HOST_WIDE_INT,
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 14259439c90..6b25d9cbfae 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -15276,6 +15276,19 @@ aarch64_asm_preferred_eh_data_format (int code ATTRIBUTE_UNUSED, int global)
    return (global ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | type;
 }
 
+/* Output .variant_pcs for aarch64_vector_pcs function symbols.  */
+
+static void
+aarch64_asm_output_variant_pcs (FILE *stream, const tree decl, const char* name)
+{
+  if (aarch64_simd_decl_p (decl))
+    {
+      fprintf (stream, "\t.variant_pcs\t");
+      assemble_name (stream, name);
+      fprintf (stream, "\n");
+    }
+}
+
 /* The last .arch and .tune assembly strings that we printed.  */
 static std::string aarch64_last_printed_arch_string;
 static std::string aarch64_last_printed_tune_string;
@@ -15325,11 +15338,34 @@ aarch64_declare_function_name (FILE *stream, const char* name,
       aarch64_last_printed_tune_string = this_tune->name;
     }
 
+  aarch64_asm_output_variant_pcs (stream, fndecl, name);
+
   /* Don't forget the type directive for ELF.  */
   ASM_OUTPUT_TYPE_DIRECTIVE (stream, name, "function");
   ASM_OUTPUT_LABEL (stream, name);
 }
 
+/* Implement ASM_OUTPUT_DEF_FROM_DECLS.  Output .variant_pcs for aliases.  */
+
+void
+aarch64_asm_output_alias (FILE *stream, const tree decl, const tree target)
+{
+  const char *name = XSTR (XEXP (DECL_RTL (decl), 0), 0);
+  const char *value = IDENTIFIER_POINTER (target);
+  aarch64_asm_output_variant_pcs (stream, decl, name);
+  ASM_OUTPUT_DEF (stream, name, value);
+}
+
+/* Implement ASM_OUTPUT_EXTERNAL.  Output .variant_pcs for undefined
+   function symbol references.  */
+
+void
+aarch64_asm_output_external (FILE *stream, tree decl, const char* name)
+{
+  default_elf_asm_output_external (stream, decl, name);
+  aarch64_asm_output_variant_pcs (stream, decl, name);
+}
+
 /* Implements TARGET_ASM_FILE_START.  Output the assembly header.  */
 
 static void
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 7bd3bf525dd..fc6df970c2e 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -505,6 +505,15 @@ extern unsigned aarch64_architecture_version;
 #define ASM_DECLARE_FUNCTION_NAME(STR, NAME, DECL)	\
   aarch64_declare_function_name (STR, NAME, DECL)
 
+/* Output assembly strings for alias definition.  */
+#define ASM_OUTPUT_DEF_FROM_DECLS(STR, DECL, TARGET) \
+  aarch64_asm_output_alias (STR, DECL, TARGET)
+
+/* Output assembly strings for undefined extern symbols.  */
+#undef ASM_OUTPUT_EXTERNAL
+#define ASM_OUTPUT_EXTERNAL(STR, DECL, NAME) \
+  aarch64_asm_output_external (STR, DECL, NAME)
+
 /* For EH returns X4 contains the stack adjustment.  */
 #define EH_RETURN_STACKADJ_RTX	gen_rtx_REG (Pmode, R4_REGNUM)
 #define EH_RETURN_HANDLER_RTX  aarch64_eh_return_handler_rtx ()
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 07b2fa79dbf..c128e1c7072 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,18 @@
+2019-07-05  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	Backport from mainline
+	2019-06-03  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* gcc.target/aarch64/pcs_attribute-2.c: New test.
+	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
+	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
+	New.
+
+	2019-06-18  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* gcc.target/aarch64/pcs_attribute-2.c: Remove ifunc usage.
+	* gcc.target/aarch64/pcs_attribute-3.c: New test.
+
 2019-07-04  Martin Liska  <mliska@suse.cz>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c
new file mode 100644
index 00000000000..e85465f25fb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-2.c
@@ -0,0 +1,93 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target aarch64_variant_pcs } */
+
+/* Test that .variant_pcs is emitted for vector PCS symbol references.  */
+
+#define ATTR __attribute__ ((aarch64_vector_pcs))
+
+void f_undef_basepcs (void);
+
+void f_def_basepcs (void)
+{
+}
+
+ATTR void f_undef_vpcs (void);
+
+ATTR void f_def_vpcs (void)
+{
+}
+
+__attribute__ ((alias ("f_def_vpcs")))
+ATTR void f_alias_vpcs (void);
+
+__attribute__ ((weak, alias ("f_def_vpcs")))
+ATTR void f_weak_alias_vpcs (void);
+
+__attribute__ ((weak))
+ATTR void f_weak_undef_vpcs (void);
+
+__attribute__ ((visibility ("protected")))
+ATTR void f_protected_vpcs (void)
+{
+}
+
+__attribute__ ((visibility ("hidden")))
+ATTR void f_hidden_vpcs (void)
+{
+}
+
+ATTR static void f_local_vpcs (void)
+{
+}
+
+__attribute__((weakref ("f_undef_vpcs")))
+ATTR static void f_local_weakref_undef_vpcs (void);
+
+__attribute__((weakref ("f_hidden_vpcs")))
+ATTR static void f_local_weakref_def_vpcs (void);
+
+ATTR void bar_undef_vpcs (void) __asm__ ("f_undef_renamed_vpcs");
+
+ATTR void bar_def_vpcs (void) __asm__ ("f_def_renamed_vpcs");
+ATTR void bar_def_vpcs (void)
+{
+}
+
+void (*refs_basepcs[]) (void) = {
+	f_undef_basepcs,
+	f_def_basepcs,
+};
+
+void (*ATTR refs_vpcs[]) (void) = {
+	f_undef_vpcs,
+	f_def_vpcs,
+	f_alias_vpcs,
+	f_weak_alias_vpcs,
+	f_weak_undef_vpcs,
+	f_protected_vpcs,
+	f_hidden_vpcs,
+	f_local_vpcs,
+	f_local_weakref_undef_vpcs,
+	f_local_weakref_def_vpcs,
+	bar_undef_vpcs,
+	bar_def_vpcs,
+};
+
+/* Note: local symbols don't need .variant_pcs, but gcc generates it, so
+   we check them here.  An undefined weakref does not show up in the
+   symbol table, only the target symbol, so it does not need .variant_pcs.  */
+
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_undef_basepcs} } } */
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_def_basepcs} } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_undef_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_def_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_alias_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_weak_alias_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_weak_undef_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_protected_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_hidden_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_vpcs} 1 } } */
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_local_weakref_undef_vpcs} } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_weakref_def_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_undef_renamed_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_def_renamed_vpcs} 1 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/pcs_attribute-3.c b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-3.c
new file mode 100644
index 00000000000..8e306af660f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pcs_attribute-3.c
@@ -0,0 +1,58 @@
+/* { dg-do compile } */
+/* { dg-require-ifunc "" } */
+/* { dg-require-effective-target aarch64_variant_pcs } */
+
+/* Test that .variant_pcs is emitted for vector PCS symbol references.  */
+
+#define ATTR __attribute__ ((aarch64_vector_pcs))
+
+static void f_local_basepcs (void)
+{
+}
+
+static void (*f_ifunc_basepcs_resolver ()) (void)
+{
+  return (void (*)(void))f_local_basepcs;
+}
+
+__attribute__ ((ifunc ("f_ifunc_basepcs_resolver")))
+void f_ifunc_basepcs (void);
+
+ATTR static void f_local_vpcs (void)
+{
+}
+
+static void (*f_ifunc_vpcs_resolver ()) (void)
+{
+  return (void (*)(void))f_local_vpcs;
+}
+
+__attribute__ ((ifunc ("f_ifunc_vpcs_resolver")))
+ATTR void f_ifunc_vpcs (void);
+
+__attribute__ ((visibility ("hidden")))
+__attribute__ ((ifunc ("f_ifunc_vpcs_resolver")))
+ATTR void f_hidden_ifunc_vpcs (void);
+
+__attribute__ ((ifunc ("f_ifunc_vpcs_resolver")))
+ATTR static void f_local_ifunc_vpcs (void);
+
+void (*refs_basepcs[]) (void) = {
+	f_ifunc_basepcs,
+};
+
+void (*ATTR refs_vpcs[]) (void) = {
+	f_ifunc_vpcs,
+	f_hidden_ifunc_vpcs,
+	f_local_ifunc_vpcs,
+};
+
+/* Note: local symbols don't need .variant_pcs, but gcc generates it, so
+   we check them here.  */
+
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_local_basepcs} } } */
+/* { dg-final { scan-assembler-not {\.variant_pcs\tf_ifunc_basepcs} } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_ifunc_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_hidden_ifunc_vpcs} 1 } } */
+/* { dg-final { scan-assembler-times {\.variant_pcs\tf_local_ifunc_vpcs} 1 } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
index e399690f364..b8d7ce09b74 100644
--- a/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
+++ b/gcc/testsuite/gcc.target/aarch64/torture/simd-abi-4.c
@@ -1,4 +1,5 @@
-/* dg-do run */
+/* { dg-do run } */
+/* { dg-require-effective-target aarch64_variant_pcs } */
 /* { dg-additional-options "-std=c99" }  */
 
 
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 737ca6d57ad..831204dc03c 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -8588,6 +8588,17 @@ proc check_effective_target_aarch64_large { } {
     }
 }
 
+# Return 1 if the assembler accepts the aarch64 .variant_pcs directive.
+
+proc check_effective_target_aarch64_variant_pcs { } {
+    if { [istarget aarch64*-*-*] } {
+	return [check_no_compiler_messages aarch64_variant_pcs object {
+	    __asm__ (".variant_pcs foo");
+	}]
+    } else {
+	return 0
+    }
+}
 
 # Return 1 if this is a reduced AVR Tiny core.  Such cores have different
 # register set, instruction set, addressing capabilities and ABI.
-- 
2.17.1

Re: [PATCH v2] aarch64: emit .variant_pcs for aarch64_vector_pcs symbol references

[Richard Sandiford]

Szabolcs Nagy <Szabolcs.Nagy@arm.com> writes:
> On 28/05/2019 16:01, Szabolcs Nagy wrote:
>> v2:
>> - use aarch64_simd_decl_p to check for aarch64_vector_pcs.
>> - emit the .variant_pcs directive even for local functions.
>> - don't require .variant_pcs asm support in compile only tests.
>> - add weakref tests.
>> 
>> A dynamic linker with lazy binding support may need to handle vector PCS
>> function symbols specially, so an ELF symbol table marking was
>> introduced for such symbols.
>> 
>> Function symbol references and definitions that follow the vector PCS
>> are marked in the generated assembly with .variant_pcs and then the
>> STO_AARCH64_VARIANT_PCS st_other flag is set on the symbol in the object
>> file.  The marking is propagated to the dynamic symbol table by the
>> static linker so a dynamic linker can handle such symbols specially.
>> 
>> For this to work, the assembler, the static linker and the dynamic
>> linker has to be updated on a system.  Old assembler does not support
>> the new .variant_pcs directive, so a toolchain with old binutils won't
>> be able to compile code that references vector PCS symbols.
>> 
>> gcc/ChangeLog:
>> 
>> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>> 
>> 	* config/aarch64/aarch64-protos.h (aarch64_asm_output_alias): Declare.
>> 	(aarch64_asm_output_external): Declare.
>> 	* config/aarch64/aarch64.c (aarch64_asm_output_variant_pcs): New.
>> 	(aarch64_declare_function_name): Call aarch64_asm_output_variant_pcs.
>> 	(aarch64_asm_output_alias): New.
>> 	(aarch64_asm_output_external): New.
>> 	* config/aarch64/aarch64.h (ASM_OUTPUT_DEF_FROM_DECLS): Define.
>> 	(ASM_OUTPUT_EXTERNAL): Define.
>> 
>> gcc/testsuite/ChangeLog:
>> 
>> 2019-05-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
>> 
>> 	* gcc.target/aarch64/pcs_attribute-2.c: New test.
>> 	* gcc.target/aarch64/torture/simd-abi-4.c: Check .variant_pcs support.
>> 	* lib/target-supports.exp (check_effective_target_aarch64_variant_pcs):
>> 	New.
>> 
>
> i'd like to backport this and follow up fixes to the gcc-9 branch,
> see attached patch.

OK.  I agree this makes sense since vector PCS functions were a new
feature in GCC 9 and since not backporting it could lead to silent
wrong code.

Richard