[PATCH v3 7/9] RISC-V: Model INSNs for LR and SC [PR 100266]

[Christoph Muellner via Gcc-patches]

In order to emit LR/SC sequences, let's provide INSNs, which
take care of memory ordering constraints.

    gcc/
        PR 100266
        * config/rsicv/sync.md (UNSPEC_LOAD_RESERVED): New.
        * config/rsicv/sync.md (UNSPEC_STORE_CONDITIONAL): New.
        * config/riscv/sync.md (riscv_load_reserved): New.
        * config/riscv/sync.md (riscv_store_conditional): New.
---
 gcc/config/riscv/sync.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/gcc/config/riscv/sync.md b/gcc/config/riscv/sync.md
index 9eb0dde9086..3494683947e 100644
--- a/gcc/config/riscv/sync.md
+++ b/gcc/config/riscv/sync.md
@@ -26,6 +26,8 @@ (define_c_enum "unspec" [
   UNSPEC_ATOMIC_LOAD
   UNSPEC_ATOMIC_STORE
   UNSPEC_MEMORY_BARRIER
+  UNSPEC_LOAD_RESERVED
+  UNSPEC_STORE_CONDITIONAL
 ])
 
 (define_code_iterator any_atomic [plus ior xor and])
@@ -113,6 +115,28 @@ (define_expand "atomic_store<mode>"
     DONE;
 })
 
+(define_insn "@riscv_load_reserved<mode>"
+  [(set (match_operand:GPR 0 "register_operand" "=r")
+    (unspec_volatile:GPR
+      [(match_operand:GPR 1 "memory_operand" "A")
+       (match_operand:SI 2 "const_int_operand")]      ;; model
+      UNSPEC_LOAD_RESERVED))]
+  "TARGET_ATOMIC"
+  "lr.<amo>%A2 %0, %1"
+)
+
+(define_insn "@riscv_store_conditional<mode>"
+  [(set (match_operand:GPR 0 "register_operand" "=&r")
+    (unspec_volatile:GPR [(const_int 0)] UNSPEC_STORE_CONDITIONAL))
+   (set (match_operand:GPR 1 "memory_operand" "=A")
+    (unspec_volatile:GPR
+      [(match_operand:GPR 2 "reg_or_0_operand" "rJ")
+       (match_operand:SI 3 "const_int_operand")]      ;; model
+      UNSPEC_STORE_CONDITIONAL))]
+  "TARGET_ATOMIC"
+  "sc.<amo>%A3 %0, %z2, %1"
+)
+
 (define_insn "atomic_<atomic_optab><mode>"
   [(set (match_operand:GPR 0 "memory_operand" "+A")
        (unspec_volatile:GPR
-- 
2.35.3