This is a proposed GCC patch that allows targets to modify the names of
the libmvec routines that get called. Currently, if you build ToT GCC
on Aarch64 and include this glibc patch:
https://sourceware.org/ml/libc-alpha/2019-03/msg00106.html
And then compile a call to expf which gets vectorized, GCC will
generate a libmvec call to '_ZGVnN4v___expf_finite' instead of
_ZGVnN4v_expf because the limvec name is based on the assembly name
of the scalar function (__expf_finite) and not the 'real' name (expf).
This means that libmvec needs to provide both names, even though the
routines don't differ.
Rather than create both names I would like to make it possible for
GCC to generate calls to libmvec based on the real name by having
a target specific function that allows GCC to use the DECL_NAME instead
of DECL_ASSEMBLER_NAME to create the libmvec name.
The responses to my glibc patch (referenced above) has a pointer
to where this was discussed in the GCC mailing list a couple of years
ago:
https://gcc.gnu.org/ml/gcc/2015-06/msg00173.html
and which has a pointer back to an older glibc string as well:
https://sourceware.org/ml/libc-alpha/2015-06/msg00213.html
Any thoughts on this patch as a way of 'fixing' GCC to not use the
finite alias names?
Steve Ellcey
sell...@marvell.com
2018-03-11 Steve Ellcey <sell...@marvell.com>
* config/aarch64/aarch64.c (aarch64_simd_clone_vec_base_name):
New function.
(TARGET_SIMD_CLONE_VEC_BASE_NAME): New macro.
* doc/tm.texi.in (TARGET_SIMD_CLONE_VEC_BASE_NAME): New hook.
* doc/tm.texi: Regenerate.
* omp-simd-clone.c (simd_clone_mangle): Call vec_base_name hook.
* target.def (vec_base_name): New hook.
* targhooks.c (cgraph.h): New include.
(default_vec_base_name): New function.
* targhooks.h (default_vec_base_name): New function declaration.
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 252bed7..cddab80 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -18711,6 +18711,14 @@ aarch64_simd_clone_usable (struct cgraph_node *node)
}
}
+/* Implement TARGET_SIMD_CLONE_VEC_BASE_NAME */
+
+static const char *
+aarch64_simd_clone_vec_base_name (struct cgraph_node *node)
+{
+ return IDENTIFIER_POINTER (DECL_NAME (node->decl));
+}
+
/* Implement TARGET_COMP_TYPE_ATTRIBUTES */
static int
@@ -19251,6 +19259,9 @@ aarch64_libgcc_floating_mode_supported_p
#undef TARGET_SIMD_CLONE_USABLE
#define TARGET_SIMD_CLONE_USABLE aarch64_simd_clone_usable
+#undef TARGET_SIMD_CLONE_VEC_BASE_NAME
+#define TARGET_SIMD_CLONE_VEC_BASE_NAME aarch64_simd_clone_vec_base_name
+
#undef TARGET_COMP_TYPE_ATTRIBUTES
#define TARGET_COMP_TYPE_ATTRIBUTES aarch64_comp_type_attributes
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index fe1194e..de4bdb42 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4196,6 +4196,8 @@ address; but often a machine-dependent strategy can generate better code.
@hook TARGET_SIMD_CLONE_USABLE
+@hook TARGET_SIMD_CLONE_VEC_BASE_NAME
+
@hook TARGET_SIMT_VF
@hook TARGET_GOACC_VALIDATE_DIMS
diff --git a/gcc/omp-simd-clone.c b/gcc/omp-simd-clone.c
index 388198b..b3a57aa 100644
--- a/gcc/omp-simd-clone.c
+++ b/gcc/omp-simd-clone.c
@@ -409,7 +409,7 @@ simd_clone_mangle (struct cgraph_node *node,
}
pp_underscore (&pp);
- const char *str = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl));
+ const char *str = targetm.simd_clone.vec_base_name (node);
if (*str == '*')
++str;
pp_string (&pp, str);
diff --git a/gcc/target.def b/gcc/target.def
index 66cee07..da60249 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -1655,6 +1655,13 @@ usable. In that case, the smaller the number is, the more desirable it is\n\
to use it.",
int, (struct cgraph_node *), NULL)
+DEFHOOK
+(vec_base_name,
+"This hook should return the name of the scalar function being cloned.\n\
+This defaults to DECL_ASSEMBLER_NAME, but targets could use DECL_NAME\n\
+instead or some other variation of the function name.",
+const char *, (struct cgraph_node *), default_vec_base_name)
+
HOOK_VECTOR_END (simd_clone)
/* Functions relating to OpenMP SIMT vectorization transform. */
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 318f7e9..6792ee5 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -83,6 +83,7 @@ along with GCC; see the file COPYING3. If not see
#include "real.h"
#include "langhooks.h"
#include "sbitmap.h"
+#include "cgraph.h"
bool
default_legitimate_address_p (machine_mode mode ATTRIBUTE_UNUSED,
@@ -2379,4 +2380,10 @@ default_remove_extra_call_preserved_regs (rtx_insn *, HARD_REG_SET *)
{
}
+const char *
+default_vec_base_name (struct cgraph_node * node)
+{
+ return IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl));
+}
+
#include "gt-targhooks.h"
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index 5943627..85dce1a 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -286,5 +286,6 @@ extern bool speculation_safe_value_not_needed (bool);
extern rtx default_speculation_safe_value (machine_mode, rtx, rtx, rtx);
extern void default_remove_extra_call_preserved_regs (rtx_insn *,
HARD_REG_SET *);
+extern const char * default_vec_base_name (struct cgraph_node *);
#endif /* GCC_TARGHOOKS_H */
