From 80f74eb50e932e2fb8c4fd3313010d611376769c Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Thu, 25 Apr 2024 18:58:18 -0700
Subject: [PATCH] [CIR][CIRGen] Atomics: handle atomic_compare_exchange_strong

---
 clang/lib/CIR/CodeGen/CIRGenAtomic.cpp |  3 ++-
 clang/test/CIR/CodeGen/atomic.cpp      | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp b/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
index 2e736206c775..d5799ddf0e93 100644
--- a/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
@@ -416,7 +416,8 @@ static void buildAtomicOp(CIRGenFunction &CGF, AtomicExpr *E, Address Dest,
   case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
   case AtomicExpr::AO__hip_atomic_compare_exchange_strong:
   case AtomicExpr::AO__opencl_atomic_compare_exchange_strong:
-    llvm_unreachable("NYI");
+    buildAtomicCmpXchgFailureSet(CGF, E, false, Dest, Ptr, Val1, Val2,
+                                 FailureOrder, Size, Order, Scope);
     return;
   case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
   case AtomicExpr::AO__opencl_atomic_compare_exchange_weak:
diff --git a/clang/test/CIR/CodeGen/atomic.cpp b/clang/test/CIR/CodeGen/atomic.cpp
index d617b627c73b..0971d47b5ca3 100644
--- a/clang/test/CIR/CodeGen/atomic.cpp
+++ b/clang/test/CIR/CodeGen/atomic.cpp
@@ -272,4 +272,15 @@ bool fi4b(int *i) {
 // LLVM-LABEL: @_Z4fi4bPi
 // LLVM: %[[R:.*]] = cmpxchg weak ptr {{.*}}, i32 {{.*}}, i32 {{.*}} acquire acquire, align 4
 // LLVM: extractvalue { i32, i1 } %[[R]], 0
-// LLVM: extractvalue { i32, i1 } %[[R]], 1
\ No newline at end of file
+// LLVM: extractvalue { i32, i1 } %[[R]], 1
+
+bool fi4c(atomic_int *i) {
+  int cmp = 0;
+  return atomic_compare_exchange_strong(i, &cmp, 1);
+}
+
+// CHECK-LABEL: @_Z4fi4cPU7_Atomici
+// CHECK: cir.atomic.cmp_xchg({{.*}} : !cir.ptr<!s32i>, {{.*}} : <!s32i>, {{.*}} : !cir.ptr<!s32i>, success = seq_cst, failure = seq_cst) : !cir.bool
+
+// LLVM-LABEL: @_Z4fi4cPU7_Atomici
+// LLVM: cmpxchg ptr {{.*}}, i32 {{.*}}, i32 {{.*}} seq_cst seq_cst, align 4
\ No newline at end of file