[ARM/FDPIC v6 04/24] [ARM] FDPIC: Add support for FDPIC for arm architecture

[ARM/FDPIC v6 04/24] [ARM] FDPIC: Add support for FDPIC for arm architecture

The FDPIC register is hard-coded to r9, as defined in the ABI.

We have to disable tailcall optimizations if we don't know if the
target function is in the same module. If not, we have to set r9 to
the value associated with the target module.

When generating a symbol address, we have to take into account whether
it is a pointer to data or to a function, because different
relocations are needed.

2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné <mickael.guene@st.com>

	gcc/
	* config/arm/arm-c.c (__FDPIC__): Define new pre-processor macro
	in FDPIC mode.
	* config/arm/arm-protos.h (arm_load_function_descriptor): Declare
	new function.
	* config/arm/arm.c (arm_option_override): Define pic register to
	FDPIC_REGNUM.
	(arm_function_ok_for_sibcall): Disable sibcall optimization if we
	have no decl or go through PLT.
	(calculate_pic_address_constant): New function.
	(legitimize_pic_address): Call calculate_pic_address_constant.
	(arm_load_pic_register): Handle TARGET_FDPIC.
	(arm_is_segment_info_known): New function.
	(arm_pic_static_addr): Add support for FDPIC.
	(arm_load_function_descriptor): New function.
	(arm_emit_call_insn): Add support for FDPIC.
	(arm_assemble_integer): Add support for FDPIC.
	* config/arm/arm.h (PIC_OFFSET_TABLE_REG_CALL_CLOBBERED):
	Define. (FDPIC_REGNUM): New define.
	* config/arm/arm.md (call): Add support for FDPIC.
	(call_value): Likewise.
	(restore_pic_register_after_call): New pattern.
	(untyped_call): Disable if FDPIC.
	(untyped_return): Likewise.
	* config/arm/unspecs.md (UNSPEC_PIC_RESTORE): New.

	gcc/testsuite/
	* gcc.target/arm/fp16-aapcs-2.c: Adjust scan-assembler-times.
	* gcc.target/arm/fp16-aapcs-4.c: Likewise.

Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
From-SVN: r275566