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[SPARC] Errata workaround for GRLIB-TN-0012

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This patch provides a workaround for the errata described in GRLIB-TN-0012.

If the workaround is enabled it will:

 * Prevent any floating-point operation from being placed in the
   delay slot of an annulled integer branch.

 * Place a NOP at the branch target of an integer branch if it is
   a floating-point operation or a floating-point branch.

It is applicable to GR712RC.

2017-11-29  Daniel Cederman  <cederman@gaisler.com>

gcc/
	* config/sparc/sparc.c (fpop_insn_p): New function.
	(sparc_do_work_around_errata): Insert NOP instructions to
	prevent sequences that could trigger the TN-0012 errata for
	GR712RC.
	(pass_work_around_errata::gate): Also test sparc_fix_gr712rc.
	* config/sparc/sparc.md (fix_gr712rc): New attribute.
	(in_branch_annul_delay): Prevent floating-point instructions
	in delay slot of annulled integer branch.

From-SVN: r255234
This commit is contained in:
Daniel Cederman 2017-11-29 15:15:48 +00:00 committed by Daniel Hellstrom
parent f7300fff74
commit dcacda0cc1
3 changed files with 84 additions and 5 deletions
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11
gcc/ChangeLog
View File

@ -1,3 +1,14 @@
2017-11-29 Daniel Cederman <cederman@gaisler.com>
* config/sparc/sparc.c (fpop_insn_p): New function.
(sparc_do_work_around_errata): Insert NOP instructions to
prevent sequences that could trigger the TN-0012 errata for
GR712RC.
(pass_work_around_errata::gate): Also test sparc_fix_gr712rc.
* config/sparc/sparc.md (fix_gr712rc): New attribute.
(in_branch_annul_delay): Prevent floating-point instructions
in delay slot of annulled integer branch.
2017-11-29 Richard Biener <rguenther@suse.de>
PR tree-optimization/83202

57
gcc/config/sparc/sparc.c
View File

@ -945,6 +945,31 @@ mem_ref (rtx x)
return NULL_RTX;
}
/* True if INSN is a floating-point instruction. */
static bool
fpop_insn_p (rtx_insn *insn)
{
if (GET_CODE (PATTERN (insn)) != SET)
return false;
switch (get_attr_type (insn))
{
case TYPE_FPMOVE:
case TYPE_FPCMOVE:
case TYPE_FP:
case TYPE_FPCMP:
case TYPE_FPMUL:
case TYPE_FPDIVS:
case TYPE_FPSQRTS:
case TYPE_FPDIVD:
case TYPE_FPSQRTD:
return true;
default:
return false;
}
}
/* We use a machine specific pass to enable workarounds for errata.
We need to have the (essentially) final form of the insn stream in order
@ -970,11 +995,34 @@ sparc_do_work_around_errata (void)
{
bool insert_nop = false;
rtx set;
rtx_insn *jump;
rtx_sequence *seq;
/* Look into the instruction in a delay slot. */
if (NONJUMP_INSN_P (insn))
if (rtx_sequence *seq = dyn_cast <rtx_sequence *> (PATTERN (insn)))
insn = seq->insn (1);
if (NONJUMP_INSN_P (insn)
&& (seq = dyn_cast <rtx_sequence *> (PATTERN (insn))))
{
jump = seq->insn (0);
insn = seq->insn (1);
}
else if (JUMP_P (insn))
jump = insn;
else
jump = NULL;
/* Place a NOP at the branch target of an integer branch if it is
a floating-point operation or a floating-point branch. */
if (sparc_fix_gr712rc
&& jump != NULL_RTX
&& get_attr_branch_type (jump) == BRANCH_TYPE_ICC)
{
rtx_insn *target = next_active_insn (JUMP_LABEL_AS_INSN (jump));
if (target
&& (fpop_insn_p (target)
|| ((JUMP_P (target)
&& get_attr_branch_type (target) == BRANCH_TYPE_FCC))))
emit_insn_before (gen_nop (), target);
}
/* Look for either of these two sequences:
@ -1303,7 +1351,8 @@ public:
/* opt_pass methods: */
virtual bool gate (function *)
{
return sparc_fix_at697f || sparc_fix_ut699 || sparc_fix_b2bst;
return sparc_fix_at697f || sparc_fix_ut699 || sparc_fix_b2bst
|| sparc_fix_gr712rc;
}
virtual unsigned int execute (function *)

21
gcc/config/sparc/sparc.md
View File

@ -430,6 +430,10 @@
(symbol_ref "(sparc_fix_b2bst != 0
? FIX_B2BST_TRUE : FIX_B2BST_FALSE)"))
(define_attr "fix_gr712rc" "false,true"
(symbol_ref "(sparc_fix_gr712rc != 0
? FIX_GR712RC_TRUE : FIX_GR712RC_FALSE)"))
;; Length (in # of insns).
;; Beware that setting a length greater or equal to 3 for conditional branches
;; has a side-effect (see output_cbranch and output_v9branch).
@ -590,6 +594,15 @@
(const_string "true")
] (const_string "false")))
(define_attr "in_integer_branch_annul_delay" "false,true"
(cond [(and (eq_attr "fix_gr712rc" "true")
(eq_attr "type" "fp,fpcmp,fpmove,fpcmove,fpmul,
fpdivs,fpsqrts,fpdivd,fpsqrtd"))
(const_string "false")
(eq_attr "in_branch_delay" "true")
(const_string "true")
] (const_string "false")))
(define_delay (eq_attr "type" "call")
[(eq_attr "in_call_delay" "true") (nil) (nil)])
@ -599,9 +612,15 @@
(define_delay (eq_attr "type" "return")
[(eq_attr "in_return_delay" "true") (nil) (nil)])
(define_delay (eq_attr "type" "branch")
(define_delay (and (eq_attr "type" "branch")
(not (eq_attr "branch_type" "icc")))
[(eq_attr "in_branch_delay" "true") (nil) (eq_attr "in_branch_delay" "true")])
(define_delay (and (eq_attr "type" "branch")
(eq_attr "branch_type" "icc"))
[(eq_attr "in_branch_delay" "true") (nil)
(eq_attr "in_integer_branch_annul_delay" "true")])
(define_delay (eq_attr "type" "uncond_branch")
[(eq_attr "in_branch_delay" "true") (nil) (nil)])