On Tue, 23 Oct 2018 at 16:07, Richard Earnshaw (lists) <richard.earns...@arm.com> wrote: > > 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? > At the moment I'm not sure about what feature is missing. It's rather that we haven't made it work it although there were preliminary attempts.
Since building GCC --with-cpu=cortex-m{0,23} --target arm-linux-gnueabi currently fails, I tried using a fdpic toolchain built --with-cpu=cortex-m4, forcing -mcpu=cortex-m{0,23} while building uClibc-ng. I noticed two kinds of failures: - parts of assembly files do not support Thumb-1, so they need porting at least (ldso/ldso/arm/dl-startup.h) - ICEs for lack of .md patterns (cortex-m4 uses pic_load_addr_32bit which is missing for m{0,23} There are probably other problems that would be discovered at runtime. So it can probably be made to work, but I think that would be an enhancement for later (not sure there's a real need: can we reasonably think about running Linux on such small cores?) > > > > 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" [ > >>> > >> > >> . > >> > > >