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Commit 07338cf8 by Hans-Peter Nilsson Committed by Hans-Peter Nilsson
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Remove workaround for register stack overwrite bug in mmix. 

	* config/mmix/mmix.c (mmix_target_asm_function_prologue): Remove
	support for TARGET_REG_STACK_FILL_BUG.
	* config/mmix/mmix.h: Remove member has_call_without_parameters.
	(TARGET_MASK_REG_STACK_FILL_BUG, TARGET_REG_STACK_FILL_BUG):
	Delete.
	(TARGET_DEFAULT): Remove TARGET_MASK_REG_STACK_FILL_BUG.
	(TARGET_SWITCHES): Remove -mreg-stack-fill-bug-workaround and
	-mno-reg-stack-fill-bug-workaround.
	* config/mmix/mmix.md ("call", "call_value"): Don't set struct
	machine member has_call_without_parameters.
	* doc/invoke.texi (Option Summary) <MMIX Options>: Remove
	-mreg-stack-fill-bug-workaround	and
	-mno-reg-stack-fill-bug-workaround.
	(MMIX Options): Ditto.

From-SVN: r49035
parent 7192cbf1
Showing with 22 additions and 76 deletions
gcc/ChangeLog
2002-01-21 Hans-Peter Nilsson <hp@bitrange.com>
Remove workaround for register stack overwrite bug in mmix.
* config/mmix/mmix.c (mmix_target_asm_function_prologue): Remove
support for TARGET_REG_STACK_FILL_BUG.
* config/mmix/mmix.h: Remove member has_call_without_parameters.
(TARGET_MASK_REG_STACK_FILL_BUG, TARGET_REG_STACK_FILL_BUG):
Delete.
(TARGET_DEFAULT): Remove TARGET_MASK_REG_STACK_FILL_BUG.
(TARGET_SWITCHES): Remove -mreg-stack-fill-bug-workaround and
-mno-reg-stack-fill-bug-workaround.
* config/mmix/mmix.md ("call", "call_value"): Don't set struct
machine member has_call_without_parameters.
* doc/invoke.texi (Option Summary) <MMIX Options>: Remove
-mreg-stack-fill-bug-workaround and
-mno-reg-stack-fill-bug-workaround.
(MMIX Options): Ditto.
2002-01-21 Kazu Hirata <kazu@hxi.com>
* config/h8300/h8300.c (function_arg): Replace 0 with NULL_RTX
......
gcc/config/mmix/mmix.c
......@@ -966,52 +966,6 @@ mmix_target_asm_function_prologue (stream, locals_size)
break;
mmix_highest_saved_stack_register = regno;
/* FIXME: Remove this when a corrected mmix version is released.
This kludge is a work-around for a presumed bug in the mmix simulator
(reported to knuth-bug), all versions up and including "Version of 14
October 2001". When the circular register stack fills up, the parts
that would be overwritten need to be written to memory. If the
"filling" instruction is a PUSHJ or PUSHGO, rL == 0 afterwards. That
precise condition (rS == rO && rL == 0) is the same as for an empty
register stack, which means no more data is written to memory for
that round. A hack is to remove the "&& L!=0" from "@<Increase
rL@>=" in mmix-sim.w: the register stack isn't empty under normal
circumstances, unless SAVE or UNSAVE is used, interrupts are enabled
or cases where rS == rO and rL is explicitly written to 0 as in
"PUT rL,0".
A workaround is to make sure PUSHJ or PUSHGO isn't filling up the
register stac. This is accomplished if $16 or higher is written
before the function call. This doesn't happen from a leaf functions
of course. For the MMIXware ABI, this can't happen if all called
functions have parameters, because parameters start at $16.
Otherwise, and for the GNU ABI, if any register $16 and up is used,
we can see if it's mentioned before any function-call without
parameters. This isn't too important; the bug will probably be fixed
soon and there's an option to not emit the work-around code. The
call-with-parameters kludge wouldn't be there if it hadn't been for
it being left-over from a previous mmix version.
The actual code makes sure any register stack fill happens as early
as in the function prologue with a "SET $16,$16" (essentially a nop
except for the effects on the register stack). */
if (TARGET_REG_STACK_FILL_BUG
&& ((TARGET_ABI_GNU && !leaf_function_p ())
|| (!TARGET_ABI_GNU
&& cfun->machine->has_call_without_parameters)))
{
/* We don't have a specific macro or derivable expression for the
first non-call-saved register. If we need it in other places
than here (which is temporary code anyway), such a macro should
be added. */
int flush_regno
= TARGET_ABI_GNU ? mmix_highest_saved_stack_register + 2 : 16;
fprintf (stream, "\tSET %s,%s\n",
reg_names[flush_regno], reg_names[flush_regno]);
}
}
/* TARGET_ASM_FUNCTION_EPILOGUE. */
......
gcc/config/mmix/mmix.h
......@@ -90,7 +90,6 @@ extern struct rtx_def *mmix_compare_op1;
mmix.md too. */
struct machine_function
{
int has_call_without_parameters;
int has_landing_pad;
};
......@@ -157,7 +156,6 @@ extern int target_flags;
#define TARGET_MASK_KNUTH_DIVISION 16
#define TARGET_MASK_TOPLEVEL_SYMBOLS 32
#define TARGET_MASK_BRANCH_PREDICT 64
#define TARGET_MASK_REG_STACK_FILL_BUG 128
/* FIXME: Get rid of this one. */
#define TARGET_LIBFUNC (target_flags & TARGET_MASK_LIBFUNCS)
......@@ -167,11 +165,9 @@ extern int target_flags;
#define TARGET_KNUTH_DIVISION (target_flags & TARGET_MASK_KNUTH_DIVISION)
#define TARGET_TOPLEVEL_SYMBOLS (target_flags & TARGET_MASK_TOPLEVEL_SYMBOLS)
#define TARGET_BRANCH_PREDICT (target_flags & TARGET_MASK_BRANCH_PREDICT)
#define TARGET_REG_STACK_FILL_BUG \
(target_flags & TARGET_MASK_REG_STACK_FILL_BUG)
#define TARGET_DEFAULT \
(TARGET_MASK_BRANCH_PREDICT | TARGET_MASK_REG_STACK_FILL_BUG)
(TARGET_MASK_BRANCH_PREDICT)
/* FIXME: Provide a way to *load* the epsilon register. */
#define TARGET_SWITCHES \
......@@ -202,12 +198,6 @@ extern int target_flags;
N_("Use P-mnemonics for branches statically predicted as taken")}, \
{"no-branch-predict", -TARGET_MASK_BRANCH_PREDICT, \
N_("Don't use P-mnemonics for branches")}, \
{"reg-stack-fill-bug-workaround", TARGET_MASK_REG_STACK_FILL_BUG, \
N_("Work around inconsistent behavior when a PUSHJ or PUSHGO\
instruction fills the register stack")}, \
{"no-reg-stack-fill-bug-workaround", -TARGET_MASK_REG_STACK_FILL_BUG,\
N_("Don't work around inconsistent behavior when a PUSHJ or PUSHGO\
instruction fills the register stack")}, \
{"", TARGET_DEFAULT, ""}}
/* Unfortunately, this must not reference anything in "mmix.c". */
......
gcc/config/mmix/mmix.md
......@@ -996,11 +996,6 @@ DIVU %1,%1,%2\;GET %0,:rR\;NEGU %2,0,%0\;CSNN %0,$255,%2")
if (operands[2] == NULL_RTX)
operands[2] = const0_rtx;
/* FIXME: Documentation bug: operands[3] (operands[2] for 'call') is the
*next* argument register, not the number of arguments in registers. */
cfun->machine->has_call_without_parameters
|= REG_P (operands[2]) && REGNO (operands[2]) == MMIX_FIRST_ARG_REGNUM;
operands[4] = gen_rtx_REG (DImode, MMIX_INCOMING_RETURN_ADDRESS_REGNUM);
}")
......@@ -1025,9 +1020,8 @@ DIVU %1,%1,%2\;GET %0,:rR\;NEGU %2,0,%0\;CSNN %0,$255,%2")
operands[3] = const0_rtx;
/* FIXME: Documentation bug: operands[3] (operands[2] for 'call') is the
*next* argument register, not the number of arguments in registers. */
cfun->machine->has_call_without_parameters
|= REG_P (operands[3]) && REGNO (operands[3]) == MMIX_FIRST_ARG_REGNUM;
*next* argument register, not the number of arguments in registers.
(There used to be code here where that mattered.) */
operands[5] = gen_rtx_REG (DImode, MMIX_INCOMING_RETURN_ADDRESS_REGNUM);
}")
......
gcc/doc/invoke.texi
......@@ -593,8 +593,7 @@ in the following sections.
@gccoptlist{
-mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu @gol
-mabi=mmixware -mzero-extend -mknuthdiv -mtoplevel-symbols @gol
-melf -mbranch-predict -mreg-stack-fill-bug-workaround @gol
-mno-branch-predict -mno-reg-stack-fill-bug-workaround}
-melf -mbranch-predict -mno-branch-predict}
@emph{IA-64 Options}
@gccoptlist{
......@@ -9486,15 +9485,6 @@ Generate an executable in the ELF format, rather than the default
@opindex mno-branch-predict
Use (do not use) the probable-branch instructions, when static branch
prediction indicates a probable branch.
@item -mreg-stack-fill-bug-workaround
@itemx -mno-reg-stack-fill-bug-workaround
@opindex mreg-stack-fill-bug-workaround
@opindex mno-reg-stack-fill-bug-workaround
Work around (do not work around) an inconsistency in the circular
register stack mechanism in the @command{mmix} simulator, which
causes entries in the register stack to not be flushed to memory if
the instruction causing the fill-up is @code{PUSHJ} or @code{PUSHGO}.
@end table
@node PDP-11 Options
......
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