On 19/10/2018 14:40, Christophe Lyon wrote:
> On 12/10/2018 12:45, Richard Earnshaw (lists) wrote:
>> On 11/10/18 14:34, Christophe Lyon wrote:
>>> 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.
>>>
>>> 2018-XX-XX Christophe Lyon <christophe.l...@st.com>
>>> Mickaël Guêné <mickael.gu...@st.com>
>>>
>>> * 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
>>
>> Missing colon.
>>
>>> have no decl or go through PLT.
>>> (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_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.
>>>
>>
>> Other comments inline.
>>
>>> diff --git a/gcc/config/arm/arm-c.c b/gcc/config/arm/arm-c.c
>>> index 4471f79..90733cc 100644
>>> --- a/gcc/config/arm/arm-c.c
>>> +++ b/gcc/config/arm/arm-c.c
>>> @@ -202,6 +202,8 @@ arm_cpu_builtins (struct cpp_reader* pfile)
>>> builtin_define ("__ARM_EABI__");
>>> }
>>> + def_or_undef_macro (pfile, "__FDPIC__", TARGET_FDPIC);
>>> +
>>> def_or_undef_macro (pfile, "__ARM_ARCH_EXT_IDIV__", TARGET_IDIV);
>>> def_or_undef_macro (pfile, "__ARM_FEATURE_IDIV", TARGET_IDIV);
>>> diff --git a/gcc/config/arm/arm-protos.h b/gcc/config/arm/arm-protos.h
>>> index 0dfb3ac..28cafa8 100644
>>> --- a/gcc/config/arm/arm-protos.h
>>> +++ b/gcc/config/arm/arm-protos.h
>>> @@ -136,6 +136,7 @@ extern int arm_max_const_double_inline_cost (void);
>>> extern int arm_const_double_inline_cost (rtx);
>>> extern bool arm_const_double_by_parts (rtx);
>>> extern bool arm_const_double_by_immediates (rtx);
>>> +extern rtx arm_load_function_descriptor (rtx funcdesc);
>>> extern void arm_emit_call_insn (rtx, rtx, bool);
>>> bool detect_cmse_nonsecure_call (tree);
>>> extern const char *output_call (rtx *);
>>> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
>>> index 8810df5..92ae24b 100644
>>> --- a/gcc/config/arm/arm.c
>>> +++ b/gcc/config/arm/arm.c
>>> @@ -3470,6 +3470,14 @@ arm_option_override (void)
>>> if (flag_pic && TARGET_VXWORKS_RTP)
>>> arm_pic_register = 9;
>>> + /* If in FDPIC mode then force arm_pic_register to be r9. */
>>> + if (TARGET_FDPIC)
>>> + {
>>> + arm_pic_register = FDPIC_REGNUM;
>>> + if (TARGET_ARM_ARCH < 7)
>>> + error ("FDPIC mode is not supported on architectures older than
>>> Armv7");
>>
>> What properties of FDPIC impose this requirement? Does it also apply to
>> Armv8-m.baseline?
>>
> In fact, there was miscommunication on my side, resulting in a
> misunderstanding between Kyrill and myself, which I badly translated
> into this condition.
>
> My initial plan was to submit a patch series tested on v7, and send the
> patches needed to support older architectures as a follow-up. The proper
> restriction is actually "CPUs that do not support ARM or Thumb2". As you
> may have noticed during the iterations of this patch series, I had
> failed to remove partial Thumb1 support hunks.
>
> So really this should be rephrased, and rewritten as "FDPIC mode is
> supported on architecture versions that support ARM or Thumb-2", if that
> suits you. And the condition should thus be:
> if (! TARGET_ARM && ! TARGET_THUMB2)
> error ("...")
>
> This would also exclude Armv8-m.baseline, since it doesn't support Thumb2.
When we get to v8-m.baseline the thumb1/2 distinction starts to become a
lot more blurred. A lot of thumb2 features needed for stand-alone
systems are then available. So what feature is it that you require in
order to make fdpic work in (traditional) thumb2 that isn't in
(traditional) thumb1?
> As a side note, I tried to build GCC master (without my patches)
> --with-cpu=cortex-m23, and both targets arm-eabi and arm-linux-gnueabi
> failed to buid.
>
> For arm-eabi, there are problems in newlib:
> newlib/libc/sys/arm/crt0.S:145: Error: lo register required -- `add
> sl,r2,#256'
> newlib/libc/sys/arm/trap.S:88: Error: lo register required -- `sub
> ip,sp,ip'
>
These all sound like basic CPU detection issues in newlib and need to be
fixed at some point (it's probably still using some pre-ACLE macros to
detect system capabilities).
R.
> For arm-linux-gnueabi, the failure happens while building libgcc:
> /home/christophe.lyon/src/GCC/sources/newlib/newlib/libc/machine/arm/setjmp.S:169:
> Error: selected processor does not support ARM opcodes
> /newlib/newlib/libc/machine/arm/setjmp.S:176: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `stmea a1!,{
> v1-v7,fp,ip,sp,lr }'
> /newlib/newlib/libc/machine/arm/setjmp.S:186: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `mov a1,#0'
> /newlib/newlib/libc/machine/arm/setjmp.S:188: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `tst lr,#1'
> /newlib/newlib/libc/machine/arm/setjmp.S:188: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `moveq pc,lr'
> /newlib/newlib/libc/machine/arm/setjmp.S:194: Error: selected processor
> does not support ARM opcodes
> /newlib/newlib/libc/machine/arm/setjmp.S:203: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `ldmfd a1!,{
> v1-v7,fp,ip,sp,lr }'
> /newlib/newlib/libc/machine/arm/setjmp.S:214: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `movs a1,a2'
> /newlib/newlib/libc/machine/arm/setjmp.S:218: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `moveq a1,#1'
> /newlib/newlib/libc/machine/arm/setjmp.S:220: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `tst lr,#1'
> /newlib/newlib/libc/machine/arm/setjmp.S:220: Error: attempt to use an
> ARM instruction on a Thumb-only processor -- `moveq pc,lr'
>
>
>>> + }
>>> +
>>> if (arm_pic_register_string != NULL)
>>> {
>>> int pic_register = decode_reg_name (arm_pic_register_string);
>>> @@ -7251,6 +7259,21 @@ arm_function_ok_for_sibcall (tree decl, tree exp)
>>> if (cfun->machine->sibcall_blocked)
>>> return false;
>>> + if (TARGET_FDPIC)
>>> + {
>>> + /* In FDPIC, never tailcall something for which we have no decl:
>>> + the target function could be in a different module, requiring
>>> + a different FDPIC register value. */
>>> + if (decl == NULL)
>>> + return false;
>>> +
>>> + /* Don't tailcall if we go through the PLT since the FDPIC
>>> + register is then corrupted and we don't restore it after
>>> + static function calls. */
>>> + if (!targetm.binds_local_p (decl))
>>> + return false;
>>> + }
>>> +
>>> /* Never tailcall something if we are generating code for
>>> Thumb-1. */
>>> if (TARGET_THUMB1)
>>> return false;
>>> @@ -7629,7 +7652,9 @@ arm_load_pic_register (unsigned long saved_regs
>>> ATTRIBUTE_UNUSED)
>>> {
>>> rtx l1, labelno, pic_tmp, pic_rtx, pic_reg;
>>> - if (crtl->uses_pic_offset_table == 0 || TARGET_SINGLE_PIC_BASE)
>>> + if (crtl->uses_pic_offset_table == 0
>>> + || TARGET_SINGLE_PIC_BASE
>>> + || TARGET_FDPIC)
>>> return;
>>> gcc_assert (flag_pic);
>>> @@ -7697,28 +7722,140 @@ arm_load_pic_register (unsigned long
>>> saved_regs ATTRIBUTE_UNUSED)
>>> emit_use (pic_reg);
>>> }
>>> +/* Try to know if the object will go in text or data segment. This is
>>
>> "Try to determine whether an object, referenced via ORIG, will be placed
>> in the text or data segment."
>>> + used in FDPIC mode, to decide which relocations to use when
>>> + accessing ORIG. IS_READONLY is set to true if ORIG is a read-only
>>
>> Two spaces after a period.
>>
>>> + location, false otherwise. */
>>
>> You've missed the documentation of the return value: does returning true
>> mean text vs data, or does it mean we know which it will go in, but
>> don't have to return that information here.
>>
>> Generally, won't this break big time if users compile with
>> -ffunction-sections or -fdata-sections? Is it sufficient to match
>> .text.* as being text and .data.* for data?
>>
>
> I compiled a small testcase with -ffunction-sections and -fdata-sections
> and noticed no problem.
> The code below does not attempt to match section names, I'm not sure to
> understand your question?
>
>>
>>> +static bool
>>> +arm_is_segment_info_known (rtx orig, bool *is_readonly)
>>> +{
>>> + bool res = false;
>>> +
>>> + *is_readonly = false;
>>> +
>>> + if (GET_CODE (orig) == LABEL_REF)
>>> + {
>>> + res = true;
>>> + *is_readonly = true;
>>> + }
>>> + else if (SYMBOL_REF_P (orig))
>>> + {
>>> + if (CONSTANT_POOL_ADDRESS_P (orig))
>>> + {
>>> + res = true;
>>> + *is_readonly = true;
>>> + }
>>> + else if (SYMBOL_REF_LOCAL_P (orig)
>>> + && !SYMBOL_REF_EXTERNAL_P (orig)
>>> + && SYMBOL_REF_DECL (orig)
>>> + && (!DECL_P (SYMBOL_REF_DECL (orig))
>>> + || !DECL_COMMON (SYMBOL_REF_DECL (orig))))
>>> + {
>>> + tree decl = SYMBOL_REF_DECL (orig);
>>> + tree init = (TREE_CODE (decl) == VAR_DECL)
>>> + ? DECL_INITIAL (decl) : (TREE_CODE (decl) == CONSTRUCTOR)
>>> + ? decl : 0;
>>> + int reloc = 0;
>>> + bool named_section, readonly;
>>> +
>>> + if (init && init != error_mark_node)
>>> + reloc = compute_reloc_for_constant (init);
>>> +
>>> + named_section = TREE_CODE (decl) == VAR_DECL
>>> + && lookup_attribute ("section", DECL_ATTRIBUTES (decl));
>>> + readonly = decl_readonly_section (decl, reloc);
>>> +
>>> + /* We don't know where the link script will put a named
>>> + section, so return false in such a case. */
>>> + res = !named_section;
>>> +
>>> + if (!named_section)
>>> + *is_readonly = readonly;
>>> + }
>>> + else
>>> + {
>>> + /* We don't know. */
>>> + res = false;
>>> + }
>>> + }
>>> + else
>>> + gcc_unreachable ();
>>> +
>>> + return res;
>>> +}
>>> +
>>> /* Generate code to load the address of a static var when flag_pic
>>> is set. */
>>> static rtx_insn *
>>> arm_pic_static_addr (rtx orig, rtx reg)
>>> {
>>> rtx l1, labelno, offset_rtx;
>>> + rtx_insn *insn;
>>> gcc_assert (flag_pic);
>>> - /* We use an UNSPEC rather than a LABEL_REF because this label
>>> - never appears in the code stream. */
>>> - labelno = GEN_INT (pic_labelno++);
>>> - l1 = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, labelno),
>>> UNSPEC_PIC_LABEL);
>>> - l1 = gen_rtx_CONST (VOIDmode, l1);
>>> + bool is_readonly = false;
>>> + bool info_known = false;
>>> - /* On the ARM the PC register contains 'dot + 8' at the time of the
>>> - addition, on the Thumb it is 'dot + 4'. */
>>> - offset_rtx = plus_constant (Pmode, l1, TARGET_ARM ? 8 : 4);
>>> - offset_rtx = gen_rtx_UNSPEC (Pmode, gen_rtvec (2, orig, offset_rtx),
>>> - UNSPEC_SYMBOL_OFFSET);
>>> - offset_rtx = gen_rtx_CONST (Pmode, offset_rtx);
>>> + if (TARGET_FDPIC
>>> + && SYMBOL_REF_P (orig)
>>> + && !SYMBOL_REF_FUNCTION_P (orig))
>>> + info_known = arm_is_segment_info_known (orig, &is_readonly);
>>> - return emit_insn (gen_pic_load_addr_unified (reg, offset_rtx,
>>> labelno));
>>> + if (TARGET_FDPIC
>>> + && SYMBOL_REF_P (orig)
>>> + && !SYMBOL_REF_FUNCTION_P (orig)
>>> + && !info_known)
>>> + {
>>> + /* We don't know where orig is stored, so we have be
>>> + pessimistic and use a GOT relocation. */
>>> + rtx pat;
>>> + rtx mem;
>>> + rtx pic_reg = gen_rtx_REG (Pmode, FDPIC_REGNUM);
>>> +
>>> + pat = gen_calculate_pic_address (reg, pic_reg, orig);
>>> +
>>> + /* Make the MEM as close to a constant as possible. */
>>> + mem = SET_SRC (pat);
>>> + gcc_assert (MEM_P (mem) && !MEM_VOLATILE_P (mem));
>>> + MEM_READONLY_P (mem) = 1;
>>> + MEM_NOTRAP_P (mem) = 1;
>>> +
>>> + insn = emit_insn (pat);
>>> + }
>>> + else if (TARGET_FDPIC
>>> + && SYMBOL_REF_P (orig)
>>> + && (SYMBOL_REF_FUNCTION_P (orig)
>>> + || (info_known && !is_readonly)))
>>> + {
>>> + /* We use the GOTOFF relocation. */
>>> + rtx pic_reg = gen_rtx_REG (Pmode, FDPIC_REGNUM);
>>> +
>>> + rtx l1 = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, orig),
>>> UNSPEC_PIC_SYM);
>>> + emit_insn (gen_movsi (reg, l1));
>>> + insn = emit_insn (gen_addsi3 (reg, reg, pic_reg));
>>> + }
>>> + else
>>> + {
>>> + /* Not FDPIC, not SYMBOL_REF_P or readonly: we can use
>>> + PC-relative access. */
>>> + /* We use an UNSPEC rather than a LABEL_REF because this label
>>> + never appears in the code stream. */
>>> + labelno = GEN_INT (pic_labelno++);
>>> + l1 = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, labelno),
>>> UNSPEC_PIC_LABEL);
>>> + l1 = gen_rtx_CONST (VOIDmode, l1);
>>> +
>>> + /* On the ARM the PC register contains 'dot + 8' at the time
>>> of the
>>> + addition, on the Thumb it is 'dot + 4'. */
>>> + offset_rtx = plus_constant (Pmode, l1, TARGET_ARM ? 8 : 4);
>>> + offset_rtx = gen_rtx_UNSPEC (Pmode, gen_rtvec (2, orig,
>>> offset_rtx),
>>> + UNSPEC_SYMBOL_OFFSET);
>>> + offset_rtx = gen_rtx_CONST (Pmode, offset_rtx);
>>> +
>>> + insn = emit_insn (gen_pic_load_addr_unified (reg, offset_rtx,
>>> + labelno));
>>> + }
>>> +
>>> + return insn;
>>> }
>>> /* Return nonzero if X is valid as an ARM state addressing
>>> register. */
>>> @@ -15933,9 +16070,36 @@ get_jump_table_size (rtx_jump_table_data *insn)
>>> return 0;
>>> }
>>> +/* Emit insns to load the function address from FUNCDESC (an FDPIC
>>> + function descriptor) into a register and the GOT address into the
>>> + FDPIC register, returning an rtx for the register holding the
>>> + function address. */
>>> +
>>> +rtx
>>> +arm_load_function_descriptor (rtx funcdesc)
>>> +{
>>> + rtx fnaddr_reg = gen_reg_rtx (Pmode);
>>> + rtx pic_reg = gen_rtx_REG (Pmode, FDPIC_REGNUM);
>>> + rtx fnaddr = gen_rtx_MEM (Pmode, funcdesc);
>>> + rtx gotaddr = gen_rtx_MEM (Pmode, plus_constant (Pmode, funcdesc,
>>> 4));
>>> + rtx par = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (3));
>>> +
>>> + emit_move_insn (fnaddr_reg, fnaddr);
>>> + /* The ABI requires the entry point address to be loaded first, so
>>> + prevent the load from being moved after that of the GOT
>>> + address. */
>>> + XVECEXP (par, 0, 0) = gen_rtx_UNSPEC (VOIDmode,
>>> + gen_rtvec (2, pic_reg, gotaddr),
>>> + UNSPEC_PIC_RESTORE);
>>> + XVECEXP (par, 0, 1) = gen_rtx_USE (VOIDmode, gen_rtx_REG (Pmode,
>>> FDPIC_REGNUM))
>>> + XVECEXP (par, 0, 2) = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG
>>> (Pmode, FDPIC_REGNUM));
>>
>> Shouldn't one of these be fnaddr_reg and the other pic_reg?
> I think the USE should be gotaddr, and CLOBBER should be pic_reg, thanks.
>
>>
>>> + emit_insn (par);
>>> +
>>> + return fnaddr_reg;
>>> +}
>>> +
>>> /* Return the maximum amount of padding that will be inserted before
>>> label LABEL. */
>>> -
>>> static HOST_WIDE_INT
>>> get_label_padding (rtx label)
>>> {
>>> @@ -22890,9 +23054,37 @@ arm_assemble_integer (rtx x, unsigned int
>>> size, int aligned_p)
>>> && (!SYMBOL_REF_LOCAL_P (x)
>>> || (SYMBOL_REF_DECL (x)
>>> ? DECL_WEAK (SYMBOL_REF_DECL (x)) : 0))))
>>> - fputs ("(GOT)", asm_out_file);
>>> + {
>>> + if (TARGET_FDPIC && SYMBOL_REF_FUNCTION_P (x))
>>> + fputs ("(GOTFUNCDESC)", asm_out_file);
>>> + else
>>> + fputs ("(GOT)", asm_out_file);
>>> + }
>>> else
>>> - fputs ("(GOTOFF)", asm_out_file);
>>> + {
>>> + if (TARGET_FDPIC && SYMBOL_REF_FUNCTION_P (x))
>>> + fputs ("(GOTOFFFUNCDESC)", asm_out_file);
>>> + else
>>> + {
>>> + bool is_readonly;
>>> +
>>> + if (arm_is_segment_info_known (x, &is_readonly))
>>> + fputs ("(GOTOFF)", asm_out_file);
>>> + else
>>> + fputs ("(GOT)", asm_out_file);
>>> + }
>>> + }
>>> + }
>>> +
>>> + /* For FDPIC we also have to mark symbol for .data section. */
>>> + if (TARGET_FDPIC
>>> + && NEED_GOT_RELOC
>>> + && flag_pic
>>> + && !making_const_table
>>> + && SYMBOL_REF_P (x))
>>> + {
>>> + if (SYMBOL_REF_FUNCTION_P (x))
>>> + fputs ("(FUNCDESC)", asm_out_file);
>>> }
>>> fputc ('\n', asm_out_file);
>>> return true;
>>> diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
>>> index 34894c0..4671d64 100644
>>> --- a/gcc/config/arm/arm.h
>>> +++ b/gcc/config/arm/arm.h
>>> @@ -871,6 +871,9 @@ extern int arm_arch_cmse;
>>> Pascal), so the following is not true. */
>>> #define STATIC_CHAIN_REGNUM 12
>>> +/* r9 is the FDPIC register (base register for GOT and FUNCDESC
>>> accesses). */
>>> +#define FDPIC_REGNUM 9
>>> +
>>> /* Define this to be where the real frame pointer is if it is not
>>> possible to
>>> work out the offset between the frame pointer and the automatic
>>> variables
>>> until after register allocation has taken place.
>>> FRAME_POINTER_REGNUM
>>> @@ -1927,6 +1930,10 @@ extern unsigned arm_pic_register;
>>> data addresses in memory. */
>>> #define PIC_OFFSET_TABLE_REGNUM arm_pic_register
>>> +/* For FDPIC, the FDPIC register is call-clobbered (otherwise PLT
>>> + entries would need to handle saving and restoring it). */
>>> +#define PIC_OFFSET_TABLE_REG_CALL_CLOBBERED TARGET_FDPIC
>>> +
>>> /* We can't directly access anything that contains a symbol,
>>> nor can we indirect via the constant pool. One exception is
>>> UNSPEC_TLS, which is always PIC. */
>>> diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
>>> index 270b8e4..09a0701 100644
>>> --- a/gcc/config/arm/arm.md
>>> +++ b/gcc/config/arm/arm.md
>>> @@ -8031,6 +8031,23 @@
>>> rtx callee, pat;
>>> tree addr = MEM_EXPR (operands[0]);
>>> + /* Force FDPIC register (r9) before call. */
>>> + if (TARGET_FDPIC)
>>> + {
>>> + /* No need to update r9 if calling a static function.
>>> + In other words: set r9 for indirect or non-local calls. */
>>> + callee = XEXP (operands[0], 0);
>>> + if (!SYMBOL_REF_P (callee)
>>> + || !SYMBOL_REF_LOCAL_P (callee)
>>> + || arm_is_long_call_p (SYMBOL_REF_DECL (callee)))
>>> + {
>>> + emit_insn (gen_blockage ());
>>> + rtx pic_reg = gen_rtx_REG (Pmode, FDPIC_REGNUM);
>>> + emit_move_insn (pic_reg, get_hard_reg_initial_val (Pmode,
>>> FDPIC_REGNUM));
>>> + emit_insn (gen_rtx_USE (VOIDmode, pic_reg));
>>> + }
>>> + }
>>> +
>>> /* In an untyped call, we can get NULL for operand 2. */
>>> if (operands[2] == NULL_RTX)
>>> operands[2] = const0_rtx;
>>> @@ -8044,6 +8061,13 @@
>>> : !REG_P (callee))
>>> XEXP (operands[0], 0) = force_reg (Pmode, callee);
>>> + if (TARGET_FDPIC && !SYMBOL_REF_P (XEXP (operands[0], 0)))
>>> + {
>>> + /* Indirect call: set r9 with FDPIC value of callee. */
>>> + XEXP (operands[0], 0)
>>> + = arm_load_function_descriptor (XEXP (operands[0], 0));
>>> + }
>>> +
>>> if (detect_cmse_nonsecure_call (addr))
>>> {
>>> pat = gen_nonsecure_call_internal (operands[0], operands[1],
>>> @@ -8055,10 +8079,38 @@
>>> pat = gen_call_internal (operands[0], operands[1], operands[2]);
>>> arm_emit_call_insn (pat, XEXP (operands[0], 0), false);
>>> }
>>> +
>>> + /* Restore FDPIC register (r9) after call. */
>>> + if (TARGET_FDPIC)
>>> + {
>>> + /* No need to update r9 if calling a static function. */
>>> + if (!SYMBOL_REF_P (callee)
>>> + || !SYMBOL_REF_LOCAL_P (callee)
>>> + || arm_is_long_call_p (SYMBOL_REF_DECL (callee)))
>>> + {
>>> + rtx pic_reg = gen_rtx_REG (Pmode, FDPIC_REGNUM);
>>> + emit_move_insn (pic_reg, get_hard_reg_initial_val (Pmode,
>>> FDPIC_REGNUM));
>>> + emit_insn (gen_rtx_USE (VOIDmode, pic_reg));
>>> + emit_insn (gen_blockage ());
>>> + }
>>> + }
>>> DONE;
>>> }"
>>> )
>>> +(define_insn "*restore_pic_register_after_call"
>>> + [(parallel [(unspec [(match_operand:SI 0 "s_register_operand" "=r,r")
>>> + (match_operand:SI 1 "nonimmediate_operand" "r,m")]
>>> + UNSPEC_PIC_RESTORE)
>>> + (use (match_dup 0))
>>> + (clobber (match_dup 0))])
>>> + ]
>>> + ""
>>> + "@
>>> + mov\t%0, %1
>>> + ldr\t%0, %1"
>>> +)
>>> +
>>> (define_expand "call_internal"
>>> [(parallel [(call (match_operand 0 "memory_operand" "")
>>> (match_operand 1 "general_operand" ""))
>>> @@ -8119,6 +8171,30 @@
>>> rtx pat, callee;
>>> tree addr = MEM_EXPR (operands[1]);
>>> + /* Force FDPIC register (r9) before call. */
>>> + if (TARGET_FDPIC)
>>> + {
>>> + /* No need to update the FDPIC register (r9) if calling a static
>>> function.
>>> + In other words: set r9 for indirect or non-local calls. */
>>> + callee = XEXP (operands[1], 0);
>>> + if (!SYMBOL_REF_P (callee)
>>> + || !SYMBOL_REF_LOCAL_P (callee)
>>> + || arm_is_long_call_p (SYMBOL_REF_DECL (callee)))
>>> + {
>>> + rtx par = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (3));
>>> +
>>> + XVECEXP (par, 0, 0) = gen_rtx_UNSPEC (VOIDmode,
>>> + gen_rtvec (2, gen_rtx_REG (Pmode, FDPIC_REGNUM),
>>> + get_hard_reg_initial_val (Pmode, FDPIC_REGNUM)),
>>> + UNSPEC_PIC_RESTORE);
>>> + XVECEXP (par, 0, 1)
>>> + = gen_rtx_USE (VOIDmode, gen_rtx_REG (Pmode, FDPIC_REGNUM));
>>> + XVECEXP (par, 0, 2)
>>> + = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (Pmode,
>>> FDPIC_REGNUM));
>>
>> Again, this looks suspicious.
>>
> Yes, fixed for follow-up patch, with
> USE for get_hard_reg_initial_val (Pmode, FDPIC_REGNUM)
> CLOBBER for gen_rtx_REG (Pmode, FDPIC_REGNUM)
>
>>> + emit_insn (par);
>>> + }
>>> + }
>>> +
>>> /* In an untyped call, we can get NULL for operand 2. */
>>> if (operands[3] == 0)
>>> operands[3] = const0_rtx;
>>> @@ -8132,6 +8208,14 @@
>>> : !REG_P (callee))
>>> XEXP (operands[1], 0) = force_reg (Pmode, callee);
>>> + if (TARGET_FDPIC
>>> + && !SYMBOL_REF_P (XEXP (operands[1], 0)))
>>> + {
>>> + /* Indirect call: set r9 with FDPIC value of callee. */
>>> + XEXP (operands[1], 0)
>>> + = arm_load_function_descriptor (XEXP (operands[1], 0));
>>> + }
>>> +
>>> if (detect_cmse_nonsecure_call (addr))
>>> {
>>> pat = gen_nonsecure_call_value_internal (operands[0], operands[1],
>>> @@ -8144,6 +8228,28 @@
>>> operands[2], operands[3]);
>>> arm_emit_call_insn (pat, XEXP (operands[1], 0), false);
>>> }
>>> + /* Restore FDPIC register (r9) after call. */
>>> + if (TARGET_FDPIC)
>>> + {
>>> + /* No need to update r9 if calling a static function. */
>>> + if (!SYMBOL_REF_P (callee)
>>> + || !SYMBOL_REF_LOCAL_P (callee)
>>> + || arm_is_long_call_p (SYMBOL_REF_DECL (callee)))
>>> + {
>>> + rtx par = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (3));
>>> +
>>> + XVECEXP (par, 0, 0) = gen_rtx_UNSPEC (VOIDmode,
>>> + gen_rtvec (2, gen_rtx_REG (Pmode, FDPIC_REGNUM),
>>> + get_hard_reg_initial_val (Pmode, FDPIC_REGNUM)),
>>> + UNSPEC_PIC_RESTORE);
>>> + XVECEXP (par, 0, 1)
>>> + = gen_rtx_USE (VOIDmode, gen_rtx_REG (Pmode, FDPIC_REGNUM));
>>> + XVECEXP (par, 0, 2)
>>> + = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (Pmode,
>>> FDPIC_REGNUM));
>>
>> And again.
> Yes
>
>>
>>> + emit_insn (par);
>>> + }
>>> + }
>>> +
>>> DONE;
>>> }"
>>> )
>>> @@ -8486,7 +8592,7 @@
>>> (const_int 0))
>>> (match_operand 1 "" "")
>>> (match_operand 2 "" "")])]
>>> - "TARGET_EITHER"
>>> + "TARGET_EITHER && !TARGET_FDPIC"
>>> "
>>> {
>>> int i;
>>> @@ -8553,7 +8659,7 @@
>>> (define_expand "untyped_return"
>>> [(match_operand:BLK 0 "memory_operand" "")
>>> (match_operand 1 "" "")]
>>> - "TARGET_EITHER"
>>> + "TARGET_EITHER && !TARGET_FDPIC"
>>> "
>>> {
>>> int i;
>>> diff --git a/gcc/config/arm/unspecs.md b/gcc/config/arm/unspecs.md
>>> index 1941673..349ae0e 100644
>>> --- a/gcc/config/arm/unspecs.md
>>> +++ b/gcc/config/arm/unspecs.md
>>> @@ -86,6 +86,7 @@
>>> UNSPEC_PROBE_STACK ; Probe stack memory reference
>>> UNSPEC_NONSECURE_MEM ; Represent non-secure memory in ARMv8-M
>>> with
>>> ; security extension
>>> + UNSPEC_PIC_RESTORE ; Use to restore fdpic register
>>> ])
>>> (define_c_enum "unspec" [
>>>
>>
>> .
>>
>
