[RISCV] Support isel for Zacas for XLen and i32. (#77666)

This adds new isel patterns for Zacas that take priority over the
pseudoinstructions we use for the A extension.

Support for 2x XLen types will come in a separate patch since they need
to be done differently.

Author: topperc

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -736,6 +736,7 @@ def FeatureStdExtZacas
 def HasStdExtZacas : Predicate<"Subtarget->hasStdExtZacas()">,
                                AssemblerPredicate<(all_of FeatureStdExtZacas),
                                "'Zacas' (Atomic Compare-And-Swap Instructions)">;
+def NoStdExtZacas : Predicate<"!Subtarget->hasStdExtZacas()">;
 
 //===----------------------------------------------------------------------===//
 // Vendor extensions

llvm/lib/Target/RISCV/RISCVInstrInfoA.td

@@ -333,11 +333,17 @@ multiclass PseudoCmpXchgPat<string Op, Pseudo CmpXchgInst,
             (CmpXchgInst GPR:$addr, GPR:$cmp, GPR:$new, 7)>;
 }
 
-let Predicates = [HasStdExtA] in {
-
+let Predicates = [HasStdExtA, NoStdExtZacas] in {
 def PseudoCmpXchg32 : PseudoCmpXchg;
 defm : PseudoCmpXchgPat<"atomic_cmp_swap_32", PseudoCmpXchg32>;
+}
+
+let Predicates = [HasStdExtA, NoStdExtZacas, IsRV64] in {
+def PseudoCmpXchg64 : PseudoCmpXchg;
+defm : PseudoCmpXchgPat<"atomic_cmp_swap_64", PseudoCmpXchg64, i64>;
+}
 
+let Predicates = [HasStdExtA] in {
 def PseudoMaskedCmpXchg32
     : Pseudo<(outs GPR:$res, GPR:$scratch),
              (ins GPR:$addr, GPR:$cmpval, GPR:$newval, GPR:$mask,
@@ -356,10 +362,6 @@ def : Pat<(int_riscv_masked_cmpxchg_i32
 } // Predicates = [HasStdExtA]
 
 let Predicates = [HasStdExtA, IsRV64] in {
-
-def PseudoCmpXchg64 : PseudoCmpXchg;
-defm : PseudoCmpXchgPat<"atomic_cmp_swap_64", PseudoCmpXchg64, i64>;
-
 def : Pat<(int_riscv_masked_cmpxchg_i64
             GPR:$addr, GPR:$cmpval, GPR:$newval, GPR:$mask, timm:$ordering),
           (PseudoMaskedCmpXchg32

llvm/lib/Target/RISCV/RISCVInstrInfoZa.td

@@ -67,6 +67,57 @@ defm AMOCAS_D_RV64 : AMO_cas_aq_rl<0b00101, 0b011, "amocas.d", GPR>;
 defm AMOCAS_Q : AMO_cas_aq_rl<0b00101, 0b100, "amocas.q", GPRPairRV64>;
 } // Predicates = [HasStdExtZacas, IsRV64]
 
+multiclass AMOCASPat<string AtomicOp, string BaseInst, ValueType vt = XLenVT,
+                     list<Predicate> ExtraPreds = []> {
+  let Predicates = !listconcat([HasStdExtZacas, NotHasStdExtZtso], ExtraPreds) in {
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_monotonic") (vt GPR:$addr),
+                                                     (vt GPR:$cmp),
+                                                     (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_acquire") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst#"_AQ") GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_release") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst#"_RL") GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_acq_rel") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst#"_AQ_RL") GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_seq_cst") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst#"_AQ_RL") GPR:$cmp, GPR:$addr, GPR:$new)>;
+  } // Predicates = !listconcat([HasStdExtZacas, NotHasStdExtZtso], ExtraPreds)
+  let Predicates = !listconcat([HasStdExtZacas, HasStdExtZtso], ExtraPreds) in {
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_monotonic") (vt GPR:$addr),
+                                                     (vt GPR:$cmp),
+                                                     (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_acquire") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_release") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_acq_rel") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+    def : Pat<(!cast<PatFrag>(AtomicOp#"_seq_cst") (vt GPR:$addr),
+                                                   (vt GPR:$cmp),
+                                                   (vt GPR:$new)),
+              (!cast<RVInst>(BaseInst) GPR:$cmp, GPR:$addr, GPR:$new)>;
+  } // Predicates = !listconcat([HasStdExtZacas, HasStdExtZtso], ExtraPreds)
+}
+
+defm : AMOCASPat<"atomic_cmp_swap_32", "AMOCAS_W">;
+defm : AMOCASPat<"atomic_cmp_swap_64", "AMOCAS_D_RV64", i64, [IsRV64]>;
+
 //===----------------------------------------------------------------------===//
 // Zawrs (Wait-on-Reservation-Set)
 //===----------------------------------------------------------------------===//