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

via llvm-commits llvm-commits at lists.llvm.org
Wed Jan 10 10:47:09 PST 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

<details>
<summary>Changes</summary>

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.

This is an alternative to #<!-- -->67918.

---

Patch is 122.35 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/77666.diff


5 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVFeatures.td (+1) 
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfoA.td (+8-6) 
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfoZa.td (+51) 
- (modified) llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll (+217-57) 
- (modified) llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll (+1700-124) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index bb7a3291085d43..279509575bb52a 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/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
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td b/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
index 1ff5189260a9c7..44552c00c62e55 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
+++ b/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
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoZa.td b/llvm/lib/Target/RISCV/RISCVInstrInfoZa.td
index ea8046d119d042..ffcdd001074938 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoZa.td
+++ b/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)
 //===----------------------------------------------------------------------===//
diff --git a/llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll b/llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll
index 651f58d324422f..a8477cc550fe6a 100644
--- a/llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll
+++ b/llvm/test/CodeGen/RISCV/atomic-cmpxchg-branch-on-result.ll
@@ -1,30 +1,44 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=riscv32 -mattr=+a -verify-machineinstrs < %s \
-; RUN:   | FileCheck -check-prefixes=CHECK,RV32IA %s
+; RUN:   | FileCheck -check-prefixes=NOZACAS,RV32IA %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+experimental-zacas -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=ZACAS,RV32IA-ZACAS %s
 ; RUN: llc -mtriple=riscv64 -mattr=+a -verify-machineinstrs < %s \
-; RUN:   | FileCheck -check-prefixes=CHECK,RV64IA %s
+; RUN:   | FileCheck -check-prefixes=NOZACAS,RV64IA %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+experimental-zacas -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=ZACAS,RV64IA-ZACAS %s
 
 ; Test cmpxchg followed by a branch on the cmpxchg success value to see if the
 ; branch is folded into the cmpxchg expansion.
 
 define void @cmpxchg_and_branch1(ptr %ptr, i32 signext %cmp, i32 signext %val) nounwind {
-; CHECK-LABEL: cmpxchg_and_branch1:
-; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:  .LBB0_1: # %do_cmpxchg
-; CHECK-NEXT:    # =>This Loop Header: Depth=1
-; CHECK-NEXT:    # Child Loop BB0_3 Depth 2
-; CHECK-NEXT:  .LBB0_3: # %do_cmpxchg
-; CHECK-NEXT:    # Parent Loop BB0_1 Depth=1
-; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
-; CHECK-NEXT:    lr.w.aqrl a3, (a0)
-; CHECK-NEXT:    bne a3, a1, .LBB0_1
-; CHECK-NEXT:  # %bb.4: # %do_cmpxchg
-; CHECK-NEXT:    # in Loop: Header=BB0_3 Depth=2
-; CHECK-NEXT:    sc.w.rl a4, a2, (a0)
-; CHECK-NEXT:    bnez a4, .LBB0_3
-; CHECK-NEXT:  # %bb.5: # %do_cmpxchg
-; CHECK-NEXT:  # %bb.2: # %exit
-; CHECK-NEXT:    ret
+; NOZACAS-LABEL: cmpxchg_and_branch1:
+; NOZACAS:       # %bb.0: # %entry
+; NOZACAS-NEXT:  .LBB0_1: # %do_cmpxchg
+; NOZACAS-NEXT:    # =>This Loop Header: Depth=1
+; NOZACAS-NEXT:    # Child Loop BB0_3 Depth 2
+; NOZACAS-NEXT:  .LBB0_3: # %do_cmpxchg
+; NOZACAS-NEXT:    # Parent Loop BB0_1 Depth=1
+; NOZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; NOZACAS-NEXT:    lr.w.aqrl a3, (a0)
+; NOZACAS-NEXT:    bne a3, a1, .LBB0_1
+; NOZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; NOZACAS-NEXT:    # in Loop: Header=BB0_3 Depth=2
+; NOZACAS-NEXT:    sc.w.rl a4, a2, (a0)
+; NOZACAS-NEXT:    bnez a4, .LBB0_3
+; NOZACAS-NEXT:  # %bb.5: # %do_cmpxchg
+; NOZACAS-NEXT:  # %bb.2: # %exit
+; NOZACAS-NEXT:    ret
+;
+; ZACAS-LABEL: cmpxchg_and_branch1:
+; ZACAS:       # %bb.0: # %entry
+; ZACAS-NEXT:  .LBB0_1: # %do_cmpxchg
+; ZACAS-NEXT:    # =>This Inner Loop Header: Depth=1
+; ZACAS-NEXT:    mv a3, a1
+; ZACAS-NEXT:    amocas.w.aqrl a3, a2, (a0)
+; ZACAS-NEXT:    bne a3, a1, .LBB0_1
+; ZACAS-NEXT:  # %bb.2: # %exit
+; ZACAS-NEXT:    ret
 entry:
   br label %do_cmpxchg
 do_cmpxchg:
@@ -36,25 +50,35 @@ exit:
 }
 
 define void @cmpxchg_and_branch2(ptr %ptr, i32 signext %cmp, i32 signext %val) nounwind {
-; CHECK-LABEL: cmpxchg_and_branch2:
-; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:  .LBB1_1: # %do_cmpxchg
-; CHECK-NEXT:    # =>This Loop Header: Depth=1
-; CHECK-NEXT:    # Child Loop BB1_3 Depth 2
-; CHECK-NEXT:  .LBB1_3: # %do_cmpxchg
-; CHECK-NEXT:    # Parent Loop BB1_1 Depth=1
-; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
-; CHECK-NEXT:    lr.w.aqrl a3, (a0)
-; CHECK-NEXT:    bne a3, a1, .LBB1_5
-; CHECK-NEXT:  # %bb.4: # %do_cmpxchg
-; CHECK-NEXT:    # in Loop: Header=BB1_3 Depth=2
-; CHECK-NEXT:    sc.w.rl a4, a2, (a0)
-; CHECK-NEXT:    bnez a4, .LBB1_3
-; CHECK-NEXT:  .LBB1_5: # %do_cmpxchg
-; CHECK-NEXT:    # in Loop: Header=BB1_1 Depth=1
-; CHECK-NEXT:    beq a3, a1, .LBB1_1
-; CHECK-NEXT:  # %bb.2: # %exit
-; CHECK-NEXT:    ret
+; NOZACAS-LABEL: cmpxchg_and_branch2:
+; NOZACAS:       # %bb.0: # %entry
+; NOZACAS-NEXT:  .LBB1_1: # %do_cmpxchg
+; NOZACAS-NEXT:    # =>This Loop Header: Depth=1
+; NOZACAS-NEXT:    # Child Loop BB1_3 Depth 2
+; NOZACAS-NEXT:  .LBB1_3: # %do_cmpxchg
+; NOZACAS-NEXT:    # Parent Loop BB1_1 Depth=1
+; NOZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; NOZACAS-NEXT:    lr.w.aqrl a3, (a0)
+; NOZACAS-NEXT:    bne a3, a1, .LBB1_5
+; NOZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; NOZACAS-NEXT:    # in Loop: Header=BB1_3 Depth=2
+; NOZACAS-NEXT:    sc.w.rl a4, a2, (a0)
+; NOZACAS-NEXT:    bnez a4, .LBB1_3
+; NOZACAS-NEXT:  .LBB1_5: # %do_cmpxchg
+; NOZACAS-NEXT:    # in Loop: Header=BB1_1 Depth=1
+; NOZACAS-NEXT:    beq a3, a1, .LBB1_1
+; NOZACAS-NEXT:  # %bb.2: # %exit
+; NOZACAS-NEXT:    ret
+;
+; ZACAS-LABEL: cmpxchg_and_branch2:
+; ZACAS:       # %bb.0: # %entry
+; ZACAS-NEXT:  .LBB1_1: # %do_cmpxchg
+; ZACAS-NEXT:    # =>This Inner Loop Header: Depth=1
+; ZACAS-NEXT:    mv a3, a1
+; ZACAS-NEXT:    amocas.w.aqrl a3, a2, (a0)
+; ZACAS-NEXT:    beq a3, a1, .LBB1_1
+; ZACAS-NEXT:  # %bb.2: # %exit
+; ZACAS-NEXT:    ret
 entry:
   br label %do_cmpxchg
 do_cmpxchg:
@@ -96,6 +120,36 @@ define void @cmpxchg_masked_and_branch1(ptr %ptr, i8 signext %cmp, i8 signext %v
 ; RV32IA-NEXT:  # %bb.2: # %exit
 ; RV32IA-NEXT:    ret
 ;
+; RV32IA-ZACAS-LABEL: cmpxchg_masked_and_branch1:
+; RV32IA-ZACAS:       # %bb.0: # %entry
+; RV32IA-ZACAS-NEXT:    andi a3, a0, -4
+; RV32IA-ZACAS-NEXT:    slli a4, a0, 3
+; RV32IA-ZACAS-NEXT:    li a0, 255
+; RV32IA-ZACAS-NEXT:    sll a0, a0, a4
+; RV32IA-ZACAS-NEXT:    andi a1, a1, 255
+; RV32IA-ZACAS-NEXT:    sll a1, a1, a4
+; RV32IA-ZACAS-NEXT:    andi a2, a2, 255
+; RV32IA-ZACAS-NEXT:    sll a2, a2, a4
+; RV32IA-ZACAS-NEXT:  .LBB2_1: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # =>This Loop Header: Depth=1
+; RV32IA-ZACAS-NEXT:    # Child Loop BB2_3 Depth 2
+; RV32IA-ZACAS-NEXT:  .LBB2_3: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # Parent Loop BB2_1 Depth=1
+; RV32IA-ZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; RV32IA-ZACAS-NEXT:    lr.w.aqrl a4, (a3)
+; RV32IA-ZACAS-NEXT:    and a5, a4, a0
+; RV32IA-ZACAS-NEXT:    bne a5, a1, .LBB2_1
+; RV32IA-ZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # in Loop: Header=BB2_3 Depth=2
+; RV32IA-ZACAS-NEXT:    xor a5, a4, a2
+; RV32IA-ZACAS-NEXT:    and a5, a5, a0
+; RV32IA-ZACAS-NEXT:    xor a5, a4, a5
+; RV32IA-ZACAS-NEXT:    sc.w.rl a5, a5, (a3)
+; RV32IA-ZACAS-NEXT:    bnez a5, .LBB2_3
+; RV32IA-ZACAS-NEXT:  # %bb.5: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:  # %bb.2: # %exit
+; RV32IA-ZACAS-NEXT:    ret
+;
 ; RV64IA-LABEL: cmpxchg_masked_and_branch1:
 ; RV64IA:       # %bb.0: # %entry
 ; RV64IA-NEXT:    andi a3, a0, -4
@@ -125,6 +179,36 @@ define void @cmpxchg_masked_and_branch1(ptr %ptr, i8 signext %cmp, i8 signext %v
 ; RV64IA-NEXT:  # %bb.5: # %do_cmpxchg
 ; RV64IA-NEXT:  # %bb.2: # %exit
 ; RV64IA-NEXT:    ret
+;
+; RV64IA-ZACAS-LABEL: cmpxchg_masked_and_branch1:
+; RV64IA-ZACAS:       # %bb.0: # %entry
+; RV64IA-ZACAS-NEXT:    andi a3, a0, -4
+; RV64IA-ZACAS-NEXT:    slli a4, a0, 3
+; RV64IA-ZACAS-NEXT:    li a0, 255
+; RV64IA-ZACAS-NEXT:    sllw a0, a0, a4
+; RV64IA-ZACAS-NEXT:    andi a1, a1, 255
+; RV64IA-ZACAS-NEXT:    sllw a1, a1, a4
+; RV64IA-ZACAS-NEXT:    andi a2, a2, 255
+; RV64IA-ZACAS-NEXT:    sllw a2, a2, a4
+; RV64IA-ZACAS-NEXT:  .LBB2_1: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # =>This Loop Header: Depth=1
+; RV64IA-ZACAS-NEXT:    # Child Loop BB2_3 Depth 2
+; RV64IA-ZACAS-NEXT:  .LBB2_3: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # Parent Loop BB2_1 Depth=1
+; RV64IA-ZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; RV64IA-ZACAS-NEXT:    lr.w.aqrl a4, (a3)
+; RV64IA-ZACAS-NEXT:    and a5, a4, a0
+; RV64IA-ZACAS-NEXT:    bne a5, a1, .LBB2_1
+; RV64IA-ZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # in Loop: Header=BB2_3 Depth=2
+; RV64IA-ZACAS-NEXT:    xor a5, a4, a2
+; RV64IA-ZACAS-NEXT:    and a5, a5, a0
+; RV64IA-ZACAS-NEXT:    xor a5, a4, a5
+; RV64IA-ZACAS-NEXT:    sc.w.rl a5, a5, (a3)
+; RV64IA-ZACAS-NEXT:    bnez a5, .LBB2_3
+; RV64IA-ZACAS-NEXT:  # %bb.5: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:  # %bb.2: # %exit
+; RV64IA-ZACAS-NEXT:    ret
 entry:
   br label %do_cmpxchg
 do_cmpxchg:
@@ -169,6 +253,39 @@ define void @cmpxchg_masked_and_branch2(ptr %ptr, i8 signext %cmp, i8 signext %v
 ; RV32IA-NEXT:  # %bb.2: # %exit
 ; RV32IA-NEXT:    ret
 ;
+; RV32IA-ZACAS-LABEL: cmpxchg_masked_and_branch2:
+; RV32IA-ZACAS:       # %bb.0: # %entry
+; RV32IA-ZACAS-NEXT:    andi a3, a0, -4
+; RV32IA-ZACAS-NEXT:    slli a4, a0, 3
+; RV32IA-ZACAS-NEXT:    li a0, 255
+; RV32IA-ZACAS-NEXT:    sll a0, a0, a4
+; RV32IA-ZACAS-NEXT:    andi a1, a1, 255
+; RV32IA-ZACAS-NEXT:    sll a1, a1, a4
+; RV32IA-ZACAS-NEXT:    andi a2, a2, 255
+; RV32IA-ZACAS-NEXT:    sll a2, a2, a4
+; RV32IA-ZACAS-NEXT:  .LBB3_1: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # =>This Loop Header: Depth=1
+; RV32IA-ZACAS-NEXT:    # Child Loop BB3_3 Depth 2
+; RV32IA-ZACAS-NEXT:  .LBB3_3: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # Parent Loop BB3_1 Depth=1
+; RV32IA-ZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; RV32IA-ZACAS-NEXT:    lr.w.aqrl a4, (a3)
+; RV32IA-ZACAS-NEXT:    and a5, a4, a0
+; RV32IA-ZACAS-NEXT:    bne a5, a1, .LBB3_5
+; RV32IA-ZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # in Loop: Header=BB3_3 Depth=2
+; RV32IA-ZACAS-NEXT:    xor a5, a4, a2
+; RV32IA-ZACAS-NEXT:    and a5, a5, a0
+; RV32IA-ZACAS-NEXT:    xor a5, a4, a5
+; RV32IA-ZACAS-NEXT:    sc.w.rl a5, a5, (a3)
+; RV32IA-ZACAS-NEXT:    bnez a5, .LBB3_3
+; RV32IA-ZACAS-NEXT:  .LBB3_5: # %do_cmpxchg
+; RV32IA-ZACAS-NEXT:    # in Loop: Header=BB3_1 Depth=1
+; RV32IA-ZACAS-NEXT:    and a4, a4, a0
+; RV32IA-ZACAS-NEXT:    beq a1, a4, .LBB3_1
+; RV32IA-ZACAS-NEXT:  # %bb.2: # %exit
+; RV32IA-ZACAS-NEXT:    ret
+;
 ; RV64IA-LABEL: cmpxchg_masked_and_branch2:
 ; RV64IA:       # %bb.0: # %entry
 ; RV64IA-NEXT:    andi a3, a0, -4
@@ -201,6 +318,39 @@ define void @cmpxchg_masked_and_branch2(ptr %ptr, i8 signext %cmp, i8 signext %v
 ; RV64IA-NEXT:    beq a1, a4, .LBB3_1
 ; RV64IA-NEXT:  # %bb.2: # %exit
 ; RV64IA-NEXT:    ret
+;
+; RV64IA-ZACAS-LABEL: cmpxchg_masked_and_branch2:
+; RV64IA-ZACAS:       # %bb.0: # %entry
+; RV64IA-ZACAS-NEXT:    andi a3, a0, -4
+; RV64IA-ZACAS-NEXT:    slli a4, a0, 3
+; RV64IA-ZACAS-NEXT:    li a0, 255
+; RV64IA-ZACAS-NEXT:    sllw a0, a0, a4
+; RV64IA-ZACAS-NEXT:    andi a1, a1, 255
+; RV64IA-ZACAS-NEXT:    sllw a1, a1, a4
+; RV64IA-ZACAS-NEXT:    andi a2, a2, 255
+; RV64IA-ZACAS-NEXT:    sllw a2, a2, a4
+; RV64IA-ZACAS-NEXT:  .LBB3_1: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # =>This Loop Header: Depth=1
+; RV64IA-ZACAS-NEXT:    # Child Loop BB3_3 Depth 2
+; RV64IA-ZACAS-NEXT:  .LBB3_3: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # Parent Loop BB3_1 Depth=1
+; RV64IA-ZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; RV64IA-ZACAS-NEXT:    lr.w.aqrl a4, (a3)
+; RV64IA-ZACAS-NEXT:    and a5, a4, a0
+; RV64IA-ZACAS-NEXT:    bne a5, a1, .LBB3_5
+; RV64IA-ZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # in Loop: Header=BB3_3 Depth=2
+; RV64IA-ZACAS-NEXT:    xor a5, a4, a2
+; RV64IA-ZACAS-NEXT:    and a5, a5, a0
+; RV64IA-ZACAS-NEXT:    xor a5, a4, a5
+; RV64IA-ZACAS-NEXT:    sc.w.rl a5, a5, (a3)
+; RV64IA-ZACAS-NEXT:    bnez a5, .LBB3_3
+; RV64IA-ZACAS-NEXT:  .LBB3_5: # %do_cmpxchg
+; RV64IA-ZACAS-NEXT:    # in Loop: Header=BB3_1 Depth=1
+; RV64IA-ZACAS-NEXT:    and a4, a4, a0
+; RV64IA-ZACAS-NEXT:    beq a1, a4, .LBB3_1
+; RV64IA-ZACAS-NEXT:  # %bb.2: # %exit
+; RV64IA-ZACAS-NEXT:    ret
 entry:
   br label %do_cmpxchg
 do_cmpxchg:
@@ -212,25 +362,35 @@ exit:
 }
 
 define void @cmpxchg_and_irrelevant_branch(ptr %ptr, i32 signext %cmp, i32 signext %val, i1 zeroext %bool) nounwind {
-; CHECK-LABEL: cmpxchg_and_irrelevant_branch:
-; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:  .LBB4_1: # %do_cmpxchg
-; CHECK-NEXT:    # =>This Loop Header: Depth=1
-; CHECK-NEXT:    # Child Loop BB4_3 Depth 2
-; CHECK-NEXT:  .LBB4_3: # %do_cmpxchg
-; CHECK-NEXT:    # Parent Loop BB4_1 Depth=1
-; CHECK-NEXT:    # => This Inner Loop Header: Depth=2
-; CHECK-NEXT:    lr.w.aqrl a4, (a0)
-; CHECK-NEXT:    bne a4, a1, .LBB4_5
-; CHECK-NEXT:  # %bb.4: # %do_cmpxchg
-; CHECK-NEXT:    # in Loop: Header=BB4_3 Depth=2
-; CHECK-NEXT:    sc.w.rl a5, a2, (a0)
-; CHECK-NEXT:    bnez a5, .LBB4_3
-; CHECK-NEXT:  .LBB4_5: # %do_cmpxchg
-; CHECK-NEXT:    # in Loop: Header=BB4_1 Depth=1
-; CHECK-NEXT:    beqz a3, .LBB4_1
-; CHECK-NEXT:  # %bb.2: # %exit
-; CHECK-NEXT:    ret
+; NOZACAS-LABEL: cmpxchg_and_irrelevant_branch:
+; NOZACAS:       # %bb.0: # %entry
+; NOZACAS-NEXT:  .LBB4_1: # %do_cmpxchg
+; NOZACAS-NEXT:    # =>This Loop Header: Depth=1
+; NOZACAS-NEXT:    # Child Loop BB4_3 Depth 2
+; NOZACAS-NEXT:  .LBB4_3: # %do_cmpxchg
+; NOZACAS-NEXT:    # Parent Loop BB4_1 Depth=1
+; NOZACAS-NEXT:    # => This Inner Loop Header: Depth=2
+; NOZACAS-NEXT:    lr.w.aqrl a4, (a0)
+; NOZACAS-NEXT:    bne a4, a1, .LBB4_5
+; NOZACAS-NEXT:  # %bb.4: # %do_cmpxchg
+; NOZACAS-NEXT:    # in Loop: Header=BB4_3 Depth=2
+; NOZACAS-NEXT:    sc.w.rl a5, a2, (a0)
+; NOZACAS-NEXT:    bnez a5, .LBB4_3
+; NOZACAS-NEXT:  .LBB4_5: # %do_cmpxchg
+; NOZACAS-NEXT:    # in Loop: Header=BB4_1 Depth=1
+; NOZACAS-NEXT:    beqz a3, .LBB4_1
+; NOZACAS-NEXT:  # %bb.2: # %exit
+; NOZACAS-NEXT:    ret
+;
+; ZACAS-LABEL: cmpxchg_and_irrelevant_branch:
+; ZACAS:       # %bb.0: # %entry
+; ZACAS-NEXT:  .LBB4_1: # %do_cmpxchg
+; ZACAS-NEXT:    # =>This Inner Loop Header: Depth=1
+; ZACAS-NEXT:    mv a4, a1
+; ZACAS-NEXT:    amocas.w.aqrl a4, a2, (a0)
+; ZACAS-NEXT:    beqz a3, .LBB4_1
+; ZACAS-NEXT:  # %bb.2: # %exit
+; ZACAS-NEXT:    ret
 entry:
   br label %do_cmpxchg
 do_cmpxchg:
diff --git a/llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll b/llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll
index 46ed01b11584f9..b3c9224646ed98 100644
--- a/llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll
+++ b/llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll
@@ -3,14 +3,22 @@
 ; RUN:   | FileCheck -check-prefix=RV32I %s
 ; RUN: llc -mtriple=riscv32 -mattr=+a -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-WMO %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+experimental-zacas -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-ZACAS,RV32IA-WMO-ZACAS %s
 ; RUN: llc -mtriple=riscv32 -mattr=+a,+experimental-ztso -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-TSO %s
+; RUN: ...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/77666


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