[ARM/FDPIC v6 09/24] [ARM] FDPIC: Add support for taking address of nested function

[ARM/FDPIC v6 09/24] [ARM] FDPIC: Add support for taking address of nested function

In FDPIC mode, the trampoline generated to support pointers to nested
functions looks like:

	   .word	trampoline address
	   .word	trampoline GOT address
	   ldr 		r12, [pc, #8]
	   ldr 		r9, [pc, #8]
	   ldr		pc, [pc, #8]
	   .word	static chain value
	   .word	GOT address
	   .word	function's address

because in FDPIC function pointers are actually pointers to function
descriptors, we have to actually generate a function descriptor for
the trampoline.

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

	gcc/
	* config/arm/arm.c (arm_asm_trampoline_template): Add FDPIC
	support.
	(arm_trampoline_init): Likewise.
	(arm_trampoline_adjust_address): Likewise.
	* config/arm/arm.h (TRAMPOLINE_SIZE): Likewise.

Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
From-SVN: r275571