[clang] [llvm] [LoongArch] Support sc.q instruction for 128bit cmpxchg operation (PR #116771)

[via cfe-commits]

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@@ -0,0 +1,342 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc --mtriple=loongarch64 -mattr=+d,-scq,-ld-seq-sa < %s | FileCheck %s --check-prefix=LA64
+; RUN: llc --mtriple=loongarch64 -mattr=+d,+scq,-ld-seq-sa < %s | FileCheck %s --check-prefixes=LA64-SCQ,NO-LD-SEQ-SA
+; RUN: llc --mtriple=loongarch64 -mattr=+d,+scq,+ld-seq-sa < %s | FileCheck %s --check-prefixes=LA64-SCQ,LD-SEQ-SA
+
+define void @cmpxchg_i128_acquire_acquire(ptr %ptr, i128 %cmp, i128 %val) nounwind {
+; LA64-LABEL: cmpxchg_i128_acquire_acquire:
+; LA64:       # %bb.0:
+; LA64-NEXT:    addi.d $sp, $sp, -32
+; LA64-NEXT:    st.d $ra, $sp, 24 # 8-byte Folded Spill
+; LA64-NEXT:    move $a6, $a4
+; LA64-NEXT:    st.d $a2, $sp, 8
+; LA64-NEXT:    st.d $a1, $sp, 0
+; LA64-NEXT:    addi.d $a1, $sp, 0
+; LA64-NEXT:    ori $a4, $zero, 2
+; LA64-NEXT:    ori $a5, $zero, 2
+; LA64-NEXT:    move $a2, $a3
+; LA64-NEXT:    move $a3, $a6
+; LA64-NEXT:    bl %plt(__atomic_compare_exchange_16)
+; LA64-NEXT:    ld.d $ra, $sp, 24 # 8-byte Folded Reload
+; LA64-NEXT:    addi.d $sp, $sp, 32
+; LA64-NEXT:    ret
+;
+; LA64-SCQ-LABEL: cmpxchg_i128_acquire_acquire:
+; LA64-SCQ:       # %bb.0:
+; LA64-SCQ-NEXT:  .LBB0_1: # =>This Inner Loop Header: Depth=1
+; LA64-SCQ-NEXT:    ll.d $a5, $a0, 0
+; LA64-SCQ-NEXT:    ld.d $a6, $a0, 8
+; LA64-SCQ-NEXT:    bne $a5, $a1, .LBB0_3
+; LA64-SCQ-NEXT:    bne $a6, $a2, .LBB0_3
+; LA64-SCQ-NEXT:  # %bb.2: # in Loop: Header=BB0_1 Depth=1
+; LA64-SCQ-NEXT:    move $a7, $a3
+; LA64-SCQ-NEXT:    sc.q $a7, $a4, $a0
+; LA64-SCQ-NEXT:    beqz $a7, .LBB0_1
+; LA64-SCQ-NEXT:    b .LBB0_4
+; LA64-SCQ-NEXT:  .LBB0_3:
+; LA64-SCQ-NEXT:    dbar 20
+; LA64-SCQ-NEXT:  .LBB0_4:
+; LA64-SCQ-NEXT:    ret
+  %res = cmpxchg ptr %ptr, i128 %cmp, i128 %val acquire acquire
+  ret void
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heiher wrote:

It is better to return result of `cmpxchg` here to help verify the correctness of its return value implementation.

https://github.com/llvm/llvm-project/pull/116771