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.
gcc/ChangeLog:
2017-11-17 Daniel Cederman <ceder...@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.
---
gcc/config/sparc/sparc.c | 57 +++++++++++++++++++++++++++++++++++++++++++----
gcc/config/sparc/sparc.md | 21 ++++++++++++++++-
2 files changed, 73 insertions(+), 5 deletions(-)
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 83ca1dc..c656b78 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -914,6 +914,31 @@ 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
@@ -939,11 +964,34 @@ 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:
@@ -1272,7 +1320,8 @@ 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 *)
diff --git a/gcc/config/sparc/sparc.md b/gcc/config/sparc/sparc.md
index 5e1f0b7..2a83bab 100644
--- a/gcc/config/sparc/sparc.md
+++ b/gcc/config/sparc/sparc.md
@@ -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)])
--
2.9.3
