The "io", "io_low", and "address" attributes require to asm output
the definition of respective symbols in a manner that was not supported
until the introduction of the new target hook TARGET_ASM_VARIABLE.
The previous implementation of these attributes abused tls_common_section
which is a noswitch section. Notice that the middle-end doesn't allow to
introduce own, custom noswitch sections.
The tls_comm_section->noswitch.callback allowed for a custom asm output
regardless of -f[no-]data-sections and -f[no-]common. However, it would
not work with checking enabled due to varasm.cc::assemble_variable()'s
/* Emulated TLS had better not get this far. */
gcc_checking_assert (targetm.have_tls || !DECL_THREAD_LOCAL_P (decl));
This patch avoids that hack and uses the new TARGET_ASM_VARIABLE target
hook to output variables with the mentioned attributes.
Ok for trunk?
Johann
--
AVR: target/112952 - Use new TARGET_ASM_VARIABLE for io, io_low, address.
The "io", "io_low", and "address" attributes require to asm output
the definition of respective symbols in a manner that was not supported
until the introduction of the new target hook TARGET_ASM_VARIABLE.
The previous implementation of these attributes abused tls_common_section
which is a noswitch section. Notice that the middle-end doesn't allow to
introduce own, custom noswitch sections.
The tls_comm_section->noswitch.callback allowed for a custom asm output
regardless of -f[no-]data-sections and -f[no-]common. However, it would
not work with checking enabled due to varasm.cc::assemble_variable()'s
/* Emulated TLS had better not get this far. */
gcc_checking_assert (targetm.have_tls || !DECL_THREAD_LOCAL_P (decl));
This patch avoids that hack and uses the new TARGET_ASM_VARIABLE target
hook to output variables with the mentioned attributes.
PR target/112952
gcc/
* config/avr/avr.cc (avr_output_addr_attrib): Rename and
rewrite to avr_asm_variable.
(avr_asm_init_sections): Leave tls_comm_section alone.
(avr_encode_section_info) [io, io_low, address]: Don't
abuse tls_comm_section.
(TARGET_ASM_VARIABLE): New define to avr_asm_variable.
diff --git a/gcc/config/avr/avr.cc b/gcc/config/avr/avr.cc
index 05a6905b5d6..a326d029412 100644
--- a/gcc/config/avr/avr.cc
+++ b/gcc/config/avr/avr.cc
@@ -11689,24 +11689,25 @@ avr_output_progmem_section_asm_op (const char *data)
}
-/* A noswitch section callback to output symbol definitions for
- attributes "io", "io_low" and "address". */
+/* Implement `TARGET_ASM_VARIABLE'. */
+/* Output symbol definitions for attributes "io", "io_low" and "address".
+ This hook is the only way to output the definitions in the required way
+ since the middle-end makes assumptions on the asm representation that
+ don't hold for these attributes. */
static bool
-avr_output_addr_attrib (tree decl, const char *name,
- unsigned HOST_WIDE_INT /* size */,
- unsigned HOST_WIDE_INT /* align */)
+avr_asm_variable (FILE *stream, tree decl, const char *name)
{
- gcc_assert (DECL_RTL_SET_P (decl));
+ rtx mem, symbol;
- FILE *stream = asm_out_file;
- bool local_p = ! DECL_WEAK (decl) && ! TREE_PUBLIC (decl);
- rtx symbol, mem = DECL_RTL (decl);
-
- if (mem != NULL_RTX && MEM_P (mem)
- && SYMBOL_REF_P ((symbol = XEXP (mem, 0)))
+ if (VAR_P (decl)
+ && DECL_RTL_SET_P (decl)
+ && MEM_P (mem = DECL_RTL (decl))
+ && SYMBOL_REF_P (symbol = XEXP (mem, 0))
&& (SYMBOL_REF_FLAGS (symbol) & (SYMBOL_FLAG_IO | SYMBOL_FLAG_ADDRESS)))
{
+ bool local_p = ! DECL_WEAK (decl) && ! TREE_PUBLIC (decl);
+
if (! local_p)
{
fprintf (stream, "\t%s\t", DECL_WEAK (decl) ? ".weak" : ".globl");
@@ -11735,8 +11736,6 @@ avr_output_addr_attrib (tree decl, const char *name,
return true;
}
- gcc_unreachable ();
-
return false;
}
@@ -11754,7 +11753,6 @@ avr_asm_init_sections (void)
readonly_data_section->unnamed.callback = avr_output_data_section_asm_op;
data_section->unnamed.callback = avr_output_data_section_asm_op;
bss_section->unnamed.callback = avr_output_bss_section_asm_op;
- tls_comm_section->noswitch.callback = avr_output_addr_attrib;
}
@@ -11974,18 +11972,11 @@ avr_encode_section_info (tree decl, rtx rtl, int new_decl_p)
}
else
{
- /* PR112952: The only way to output a variable declaration in a
- custom manner is by means of a noswitch section callback.
- There are only three noswitch sections: comm_section,
- lcomm_section and tls_comm_section. And there is no way to
- wire a custom noswitch section to a decl. As lcomm_section
- is bypassed with -fdata-sections -fno-common, there is no
- other way than making use of tls_comm_section. As we are
- using that section anyway, also use it in the public case. */
-
- DECL_COMMON (decl) = 1;
+ /* PR112952: Thanks to TARGET_ASM_VARIABLE, we can output
+ a variable / symbol definition in a custom way entirely.
+ There's no more need to abuse tls_comm_section. */
+
set_decl_section_name (decl, (const char *) nullptr);
- set_decl_tls_model (decl, (tls_model) 2);
}
}
}
@@ -16076,6 +16067,9 @@ avr_use_lra_p ()
#undef TARGET_ASM_FUNCTION_BEGIN_EPILOGUE
#define TARGET_ASM_FUNCTION_BEGIN_EPILOGUE avr_asm_function_begin_epilogue
+#undef TARGET_ASM_VARIABLE
+#define TARGET_ASM_VARIABLE avr_asm_variable
+
#undef TARGET_FUNCTION_VALUE
#define TARGET_FUNCTION_VALUE avr_function_value
#undef TARGET_LIBCALL_VALUE
