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Commit 2c8ec431 by Don Lindsay Committed by Don Lindsay
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Added -mpcrel flag, and underlying support for PC-relative addressing on m68k. 

h
Added -mpcrel flag, and underlying support for PC-relative addressing
on m68k. Patch is tested, and approved by Jim Wilson.

From-SVN: r27576
parent fb868474
Showing with 279 additions and 14 deletions
ChangeLog
Thu Jun 17 15:06:10 PDT 1999 Don Lindsay <dlindsay@cygnus.com>
* added support for -mpcrel (PC relative addressing for m68k)
based on code done by Michael Tiemann <tiemann@axon.cygnus.com>.
* invoke.texi (m68000 options): Add documentation for -mpcrel flag.
* m68k.c (print_operand_address): Handle 32-bit PIC case.
(comments for general_src_operand): Add some explanation
about EXTRA_CONSTRAINTS.
(OVERRIDE_OPTIONS): Enable -fPIC in combination with -mpcrel.
* m68kelf.h (OVERRIDE_OPTIONS): Ditto.
(LEGITIMATE_PIC_OPERAND_P): Fix typo.
(LEGITIMATE_PIC_OPERAND_P): Re-derive from m68k.h case.
* m68k.h (LEGITIMATE_PIC_OPERAND_P): Fix delete-o.
(INDIRECTABLE_1_ADDRESS): Delete spurious '/' at end of macro.
(OVERRIDE_OPTIONS): Change behavior so that -mpcrel implies -fpic
if not already set.
(OVERRIDE_OPTIONS): Merge in changes from m68k.h.
* m68k.h (TARGET_PCREL): New target flag.
(TARGET_SWITCHES): Add "pcrel" as a recognized switch.
(OVERRIDE_OPTIONS): Add checks for -mpcrel.
(LEGITIMATE_PIC_OPERAND_P): Don't normally accept anything that
contains a SYMBOL_REF. Relax this constraint during reload, since
we want to use the predicates, not reload's built-in concept of a
valid memory address, to control what insns need reloading.
(EXTRA_CONSTRAINT): Define constraints to accept pc-relative
operands (essentially 'g', 'm', and 's' under normal circumstances).
* m68k.c (print_operand): Cause printing of pc-relative addresses
to include pc register.
(print_operand_address): Ditto.
(general_src_operand): Accept operands that are not only
general_operands, but are also valid when used as a pc-relative
source.
(nonimmediate_src_operand): Similar, for nonimmediate_operands.
(memory_src_operand): Similar, for memory_operands.
(pcrel_address): New predicate to accept the special case of a
pc-relative address.
* m68k.md (many patterns): Rewrite common SImode, HImode, and
QImode insns to accept *_src_operand instead of *_operand where
pc-relative operands can fit. For example, a pc-relative operand
can be used as a memory source operand for addsi3, but not as a
memory destination.
* hp320.h linux.h m68kv4.h (LEGITIMATE_PIC_OPERAND_P) as in m68k.h.
Sun May 30 16:03:16 1999 Cort Dougan <cort@cs.nmt.edu>
* config.guess (ppc-*-linux-gnu): Also use ld emul elf32ppclinux.
......
gcc/config/m68k/hp320.h
......@@ -635,7 +635,8 @@ do { register int i; \
&& ! (GET_CODE (X) == CONST_DOUBLE && CONST_DOUBLE_MEM (X) \
&& GET_CODE (CONST_DOUBLE_MEM (X)) == MEM \
&& symbolic_operand (XEXP (CONST_DOUBLE_MEM (X), 0), VOIDmode))) \
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)))
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)) \
|| PCREL_GENERAL_OPERAND_OK)
/* hpux8 and later have C++ compatible include files, so do not
pretend they are `extern "C"'. */
......
gcc/config/m68k/linux.h
......@@ -310,7 +310,8 @@ do { \
&& ! (GET_CODE (X) == CONST_DOUBLE && CONST_DOUBLE_MEM (X) \
&& GET_CODE (CONST_DOUBLE_MEM (X)) == MEM \
&& symbolic_operand (XEXP (CONST_DOUBLE_MEM (X), 0), VOIDmode))) \
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)))
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)) \
|| PCREL_GENERAL_OPERAND_OK)
/* Turn off function cse if we are doing PIC. We always want function
call to be done as `bsr foo@PLTPC', so it will force the assembler
......
gcc/config/m68k/m68k.c
......@@ -54,6 +54,7 @@ int switch_table_difference_label_flag;
static rtx find_addr_reg ();
rtx legitimize_pic_address ();
void print_operand_address ();
/* Alignment to use for loops and jumps */
......@@ -2717,6 +2718,8 @@ standard_sun_fpa_constant_p (x)
'b' for byte insn (no effect, on the Sun; this is for the ISI).
'd' to force memory addressing to be absolute, not relative.
'f' for float insn (print a CONST_DOUBLE as a float rather than in hex)
'o' for operands to go directly to output_operand_address (bypassing
print_operand_address--used only for SYMBOL_REFs under TARGET_PCREL)
'w' for FPA insn (print a CONST_DOUBLE as a SunFPA constant rather
than directly). Second part of 'y' below.
'x' for float insn (print a CONST_DOUBLE as a float rather than in hex),
......@@ -2793,6 +2796,14 @@ print_operand (file, op, letter)
{
asm_fprintf (file, "%R");
}
else if (letter == 'o')
{
/* This is only for direct addresses with TARGET_PCREL */
if (GET_CODE (op) != MEM || GET_CODE (XEXP (op, 0)) != SYMBOL_REF
|| !TARGET_PCREL)
abort ();
output_addr_const (file, XEXP (op, 0));
}
else if (GET_CODE (op) == REG)
{
#ifdef SUPPORT_SUN_FPA
......@@ -2858,7 +2869,14 @@ print_operand (file, op, letter)
}
else
{
asm_fprintf (file, "%0I"); output_addr_const (file, op);
/* Use `print_operand_address' instead of `output_addr_const'
to ensure that we print relevant PIC stuff. */
asm_fprintf (file, "%0I");
if (TARGET_PCREL
&& (GET_CODE (op) == SYMBOL_REF || GET_CODE (op) == CONST))
print_operand_address (file, op);
else
output_addr_const (file, op);
}
}
......@@ -3159,7 +3177,7 @@ print_operand_address (file, addr)
fprintf (file, "l)");
break;
}
/* FALL-THROUGH (is this really what we want? */
/* FALL-THROUGH (is this really what we want?) */
default:
if (GET_CODE (addr) == CONST_INT
&& INTVAL (addr) < 0x8000
......@@ -3176,6 +3194,25 @@ print_operand_address (file, addr)
fprintf (file, "%d:w", INTVAL (addr));
#endif
}
else if (GET_CODE (addr) == CONST_INT)
{
fprintf (file,
#if HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_INT
"%d",
#else
"%ld",
#endif
INTVAL (addr));
}
else if (TARGET_PCREL)
{
fputc ('(', file);
output_addr_const (file, addr);
if (flag_pic == 1)
asm_fprintf (file, ":w,%Rpc)");
else
asm_fprintf (file, ":l,%Rpc)");
}
else
{
/* Special case for SYMBOL_REF if the symbol name ends in
......@@ -3288,6 +3325,128 @@ const_sint32_operand (op, mode)
&& (INTVAL (op) >= (-0x7fffffff - 1) && INTVAL (op) <= 0x7fffffff));
}
/* Operand predicates for implementing asymmetric pc-relative addressing
on m68k. The m68k supports pc-relative addressing (mode 7, register 2)
when used as a source operand, but not as a destintation operand.
We model this by restricting the meaning of the basic predicates
(general_operand, memory_operand, etc) to forbid the use of this
addressing mode, and then define the following predicates that permit
this addressing mode. These predicates can then be used for the
source operands of the appropriate instructions.
n.b. While it is theoretically possible to change all machine patterns
to use this addressing more where permitted by the architecture,
it has only been implemented for "common" cases: SImode, HImode, and
QImode operands, and only for the principle operations that would
require this addressing mode: data movement and simple integer operations.
In parallel with these new predicates, two new constraint letters
were defined: 'S' and 'T'. 'S' is the -mpcrel analog of 'm'.
'T' replaces 's' in the non-pcrel case. It is a no-op in the pcrel case.
In the pcrel case 's' is only valid in combination with 'a' registers.
See addsi3, subsi3, cmpsi, and movsi patterns for a better understanding
of how these constraints are used.
The use of these predicates is strictly optional, though patterns that
don't will cause an extra reload register to be allocated where one
was not necessary:
lea (abc:w,%pc),%a0 ; need to reload address
moveq &1,%d1 ; since write to pc-relative space
movel %d1,%a0@ ; is not allowed
...
lea (abc:w,%pc),%a1 ; no need to reload address here
movel %a1@,%d0 ; since "movel (abc:w,%pc),%d0" is ok
For more info, consult tiemann@cygnus.com.
All of the ugliness with predicates and constraints is due to the
simple fact that the m68k does not allow a pc-relative addressing
mode as a destination. gcc does not distinguish between source and
destination addresses. Hence, if we claim that pc-relative address
modes are valid, e.g. GO_IF_LEGITIMATE_ADDRESS accepts them, then we
end up with invalid code. To get around this problem, we left
pc-relative modes as invalid addresses, and then added special
predicates and constraints to accept them.
A cleaner way to handle this is to modify gcc to distinguish
between source and destination addresses. We can then say that
pc-relative is a valid source address but not a valid destination
address, and hopefully avoid a lot of the predicate and constraint
hackery. Unfortunately, this would be a pretty big change. It would
be a useful change for a number of ports, but there aren't any current
plans to undertake this.
***************************************************************************/
/* Special case of a general operand that's used as a source operand.
Use this to permit reads from PC-relative memory when -mpcrel
is specified. */
int
general_src_operand (op, mode)
rtx op;
enum machine_mode mode;
{
if (TARGET_PCREL
&& GET_CODE (op) == MEM
&& (GET_CODE (XEXP (op, 0)) == SYMBOL_REF
|| GET_CODE (XEXP (op, 0)) == LABEL_REF
|| GET_CODE (XEXP (op, 0)) == CONST))
return 1;
return general_operand (op, mode);
}
/* Special case of a nonimmediate operand that's used as a source.
Use this to permit reads from PC-relative memory when -mpcrel
is specified. */
int
nonimmediate_src_operand (op, mode)
rtx op;
enum machine_mode mode;
{
if (TARGET_PCREL && GET_CODE (op) == MEM
&& (GET_CODE (XEXP (op, 0)) == SYMBOL_REF
|| GET_CODE (XEXP (op, 0)) == LABEL_REF
|| GET_CODE (XEXP (op, 0)) == CONST))
return 1;
return nonimmediate_operand (op, mode);
}
/* Special case of a memory operand that's used as a source.
Use this to permit reads from PC-relative memory when -mpcrel
is specified. */
int
memory_src_operand (op, mode)
rtx op;
enum machine_mode mode;
{
if (TARGET_PCREL && GET_CODE (op) == MEM
&& (GET_CODE (XEXP (op, 0)) == SYMBOL_REF
|| GET_CODE (XEXP (op, 0)) == LABEL_REF
|| GET_CODE (XEXP (op, 0)) == CONST))
return 1;
return memory_operand (op, mode);
}
/* Predicate that accepts only a pc-relative address. This is needed
because pc-relative addresses don't satisfy the predicate
"general_src_operand". */
int
pcrel_address (op, mode)
rtx op;
enum machine_mode mode;
{
return (GET_CODE (op) == SYMBOL_REF || GET_CODE (op) == LABEL_REF
|| GET_CODE (op) == CONST);
}
char *
output_andsi3 (operands)
rtx *operands;
......
gcc/config/m68k/m68k.h
......@@ -123,6 +123,18 @@ extern int target_flags;
/* A 68020 without bitfields is a good heuristic for a CPU32 */
#define TARGET_CPU32 (TARGET_68020 && !TARGET_BITFIELD)
/* Use PC-relative addressing modes (without using a global offset table).
The m68000 supports 16-bit PC-relative addressing.
The m68020 supports 32-bit PC-relative addressing
(using outer displacements).
Under this model, all SYMBOL_REFs (and CONSTs) and LABEL_REFs are
treated as all containing an implicit PC-relative component, and hence
cannot be used directly as addresses for memory writes. See the comments
in m68k.c for more information. */
#define MASK_PCREL 4096
#define TARGET_PCREL (target_flags & MASK_PCREL)
/* Macro to define tables used to set the flags.
This is a list in braces of pairs in braces,
each pair being { "NAME", VALUE }
......@@ -181,6 +193,7 @@ extern int target_flags;
{ "cpu32", MASK_68020}, \
{ "align-int", MASK_ALIGN_INT }, \
{ "no-align-int", -MASK_ALIGN_INT }, \
{ "pcrel", MASK_PCREL}, \
SUBTARGET_SWITCHES \
{ "", TARGET_DEFAULT}}
/* TARGET_DEFAULT is defined in sun*.h and isi.h, etc. */
......@@ -215,6 +228,8 @@ extern int target_flags;
override_options(); \
if (! TARGET_68020 && flag_pic == 2) \
error("-fPIC is not currently supported on the 68000 or 68010\n"); \
if (TARGET_PCREL && flag_pic == 0) \
flag_pic = 1; \
SUBTARGET_OVERRIDE_OPTIONS; \
}
......@@ -760,11 +775,35 @@ extern enum reg_class regno_reg_class[];
C. If C is not defined as an extra constraint, the value returned should
be 0 regardless of VALUE. */
/* For the m68k, `Q' means address register indirect addressing mode. */
#define EXTRA_CONSTRAINT(OP, C) \
((C) == 'Q' ? (GET_CODE (OP) == MEM && GET_CODE (XEXP (OP, 0)) == REG) : \
0 )
/* Letters in the range `Q' through `U' may be defined in a
machine-dependent fashion to stand for arbitrary operand types.
The machine description macro `EXTRA_CONSTRAINT' is passed the
operand as its first argument and the constraint letter as its
second operand.
`Q' means address register indirect addressing mode.
`S' is for operands that satisfy 'm' when -mpcrel is in effect.
`T' is for operands that satisfy 's' when -mpcrel is not in effect. */
#define EXTRA_CONSTRAINT(OP,CODE) \
(((CODE) == 'S') \
? (TARGET_PCREL \
&& GET_CODE (OP) == MEM \
&& (GET_CODE (XEXP (OP, 0)) == SYMBOL_REF \
|| GET_CODE (XEXP (OP, 0)) == LABEL_REF \
|| GET_CODE (XEXP (OP, 0)) == CONST)) \
: \
(((CODE) == 'T') \
? ( !TARGET_PCREL \
&& (GET_CODE (OP) == SYMBOL_REF \
|| GET_CODE (OP) == LABEL_REF \
|| GET_CODE (OP) == CONST)) \
: \
(((CODE) == 'Q') \
? (GET_CODE (OP) == MEM \
&& GET_CODE (XEXP (OP, 0)) == REG) \
: \
0)))
/* Given an rtx X being reloaded into a reg required to be
in class CLASS, return the class of reg to actually use.
......@@ -789,6 +828,10 @@ extern enum reg_class regno_reg_class[];
? (! CONST_DOUBLE_OK_FOR_LETTER_P (X, 'G') \
&& (CLASS == FP_REGS || CLASS == DATA_OR_FP_REGS) \
? FP_REGS : NO_REGS) \
: (TARGET_PCREL \
&& (GET_CODE (X) == SYMBOL_REF || GET_CODE (X) == CONST \
|| GET_CODE (X) == LABEL_REF)) \
? ADDR_REGS \
: (CLASS))
/* Force QImode output reloads from subregs to be allocated to data regs,
......@@ -1353,7 +1396,17 @@ __transfer_from_trampoline () \
/* Nonzero if the constant value X is a legitimate general operand
when generating PIC code. It is given that flag_pic is on and
that X satisfies CONSTANT_P or is a CONST_DOUBLE. */
that X satisfies CONSTANT_P or is a CONST_DOUBLE.
PCREL_GENERAL_OPERAND_OK makes reload accept addresses that are
accepted by insn predicates, but which would otherwise fail the
`general_operand' test. */
#ifndef REG_OK_STRICT
#define PCREL_GENERAL_OPERAND_OK 0
#else
#define PCREL_GENERAL_OPERAND_OK (TARGET_PCREL)
#endif
#define LEGITIMATE_PIC_OPERAND_P(X) \
((! symbolic_operand (X, VOIDmode) \
......@@ -1361,7 +1414,8 @@ __transfer_from_trampoline () \
&& GET_CODE (CONST_DOUBLE_MEM (X)) == MEM \
&& symbolic_operand (XEXP (CONST_DOUBLE_MEM (X), 0), \
VOIDmode))) \
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)))
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)) \
|| PCREL_GENERAL_OPERAND_OK)
/* The macros REG_OK_FOR..._P assume that the arg is a REG rtx
and check its validity for a certain class.
......@@ -1431,7 +1485,7 @@ __transfer_from_trampoline () \
|| (GET_CODE (X) == PLUS && XEXP (X, 0) == pic_offset_table_rtx \
&& flag_pic && GET_CODE (XEXP (X, 1)) == SYMBOL_REF) \
|| (GET_CODE (X) == PLUS && XEXP (X, 0) == pic_offset_table_rtx \
&& flag_pic && GET_CODE (XEXP (X, 1)) == LABEL_REF)) \
&& flag_pic && GET_CODE (XEXP (X, 1)) == LABEL_REF))
#define GO_IF_NONINDEXED_ADDRESS(X, ADDR) \
{ if (INDIRECTABLE_1_ADDRESS_P (X)) goto ADDR; }
......@@ -2032,6 +2086,8 @@ do { long l; \
'b' for byte insn (no effect, on the Sun; this is for the ISI).
'd' to force memory addressing to be absolute, not relative.
'f' for float insn (print a CONST_DOUBLE as a float rather than in hex)
'o' for operands to go directly to output_operand_address (bypassing
print_operand_address--used only for SYMBOL_REFs under TARGET_PCREL)
'w' for FPA insn (print a CONST_DOUBLE as a SunFPA constant rather
than directly). Second part of 'y' below.
'x' for float insn (print a CONST_DOUBLE as a float rather than in hex),
......
gcc/config/m68k/m68kelf.h
......@@ -246,9 +246,11 @@ extern int switch_table_difference_label_flag;
/* In m68k svr4, a symbol_ref rtx can be a valid PIC operand if it is an
operand of a function call. */
#undef LEGITIMATE_PIC_OPERAND_P
#define LEGITIMATE_PIC_OPERAND_P(X) \
(! symbolic_operand (X, VOIDmode) \
|| ((GET_CODE(X) == SYMBOL_REF) && SYMBOL_REF_FLAG(X)))
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)) \
|| PCREL_GENERAL_OPERAND_OK)
/* Turn off function cse if we are doing PIC. We always want function call
to be done as `bsr foo@PLTPC', so it will force the assembler to create
......@@ -261,6 +263,8 @@ extern int switch_table_difference_label_flag;
if (flag_pic) flag_no_function_cse = 1; \
if (! TARGET_68020 && flag_pic == 2) \
error("-fPIC is not currently supported on the 68000 or 68010\n"); \
if (TARGET_PCREL && flag_pic == 0) \
flag_pic = 1; \
}
/* end of stuff from m68kv4.h */
......
gcc/config/m68k/m68kv4.h
......@@ -297,7 +297,8 @@ int switch_table_difference_label_flag;
&& ! (GET_CODE (X) == CONST_DOUBLE && CONST_DOUBLE_MEM (X) \
&& GET_CODE (CONST_DOUBLE_MEM (X)) == MEM \
&& symbolic_operand (XEXP (CONST_DOUBLE_MEM (X), 0), VOIDmode))) \
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)))
|| (GET_CODE (X) == SYMBOL_REF && SYMBOL_REF_FLAG (X)) \
|| PCREL_GENERAL_OPERAND_OK)
/* Turn off function cse if we are doing PIC. We always want function call
to be done as `bsr foo@PLTPC', so it will force the assembler to create
......
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