diff mbox series

[2/2] sparc: Add errata workaround to membar patterns

Message ID 20240105071913.593978-4-cederman@gaisler.com
State New
Headers show
Series [1/2] sparc: Revert membar optimization that is not suitable for LEON5 | expand

Commit Message

Daniel Cederman Jan. 5, 2024, 7:19 a.m. UTC 
LEON now uses the standard V8 membar patterns that contains an ldstub
instruction. This instruction needs to be aligned properly when the
GR712RC errata workaround is enabled.

gcc/ChangeLog:

	* config/sparc/sparc.cc (atomic_insn_for_leon3_p): Treat membar_storeload as atomic
	* config/sparc/sync.md: Add GR712RC errata workaround
---
 gcc/config/sparc/sparc.cc |  1 +
 gcc/config/sparc/sync.md  | 23 ++++++++++++++++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)

Comments

Eric Botcazou Jan. 8, 2024, 9:32 a.m. UTC | #1 
> LEON now uses the standard V8 membar patterns that contains an ldstub
> instruction. This instruction needs to be aligned properly when the
> GR712RC errata workaround is enabled.
> 
> gcc/ChangeLog:
> 
> 	* config/sparc/sparc.cc (atomic_insn_for_leon3_p): Treat 
membar_storeload as atomic
> 	* config/sparc/sync.md: Add GR712RC errata workaround

The second ChangeLog entry should be more detailed:

	* config/sparc/sync.md (membar_storeload): Turn into named insn
	and add GR712RC errata workaround.
	(membar_v8): Add GR712RC errata workaround.

OK with this change.
diff mbox series

Patch

diff --git a/gcc/config/sparc/sparc.cc b/gcc/config/sparc/sparc.cc
index ebf1a557a49d..62c57cc53159 100644
--- a/gcc/config/sparc/sparc.cc
+++ b/gcc/config/sparc/sparc.cc
@@ -1052,6 +1052,7 @@  atomic_insn_for_leon3_p (rtx_insn *insn)
 {
   switch (INSN_CODE (insn))
     {
+    case CODE_FOR_membar_storeload:
     case CODE_FOR_swapsi:
     case CODE_FOR_ldstub:
     case CODE_FOR_atomic_compare_and_swap_leon3_1:
diff --git a/gcc/config/sparc/sync.md b/gcc/config/sparc/sync.md
index ac291420b8b9..fa249908a55f 100644
--- a/gcc/config/sparc/sync.md
+++ b/gcc/config/sparc/sync.md
@@ -65,12 +65,19 @@ 
   [(set_attr "type" "multi")])
 
 ;; For V8, LDSTUB has the effect of membar #StoreLoad.
-(define_insn "*membar_storeload"
+(define_insn "membar_storeload"
   [(set (match_operand:BLK 0 "" "")
 	(unspec:BLK [(match_dup 0) (const_int 2)] UNSPEC_MEMBAR))]
   "TARGET_V8"
-  "ldstub\t[%%sp-1], %%g0"
-  [(set_attr "type" "multi")])
+{
+  if (sparc_fix_gr712rc)
+    return ".align\t16\n\tldstub\t[%%sp-1], %%g0";
+  else
+    return "ldstub\t[%%sp-1], %%g0";
+}
+  [(set_attr "type" "multi")
+   (set (attr "length") (if_then_else (eq_attr "fix_gr712rc" "true")
+		      (const_int 4) (const_int 1)))])
 
 ;; Put the two together, in combination with the fact that V8 implements PSO
 ;; as its weakest memory model, means a full barrier.  Match all remaining
@@ -80,9 +87,15 @@ 
 	(unspec:BLK [(match_dup 0) (match_operand:SI 1 "const_int_operand")]
 		    UNSPEC_MEMBAR))]
   "TARGET_V8"
-  "stbar\n\tldstub\t[%%sp-1], %%g0"
+{
+  if (sparc_fix_gr712rc)
+    return "stbar\n.align\t16\n\tldstub\t[%%sp-1], %%g0";
+  else
+    return "stbar\n\tldstub\t[%%sp-1], %%g0";
+}
   [(set_attr "type" "multi")
-   (set_attr "length" "2")])
+   (set (attr "length") (if_then_else (eq_attr "fix_gr712rc" "true")
+		      (const_int 5) (const_int 2)))])
 
 ;; For V9, we have the full membar instruction.
 (define_insn "*membar"