[AArch64][CodeGen] Add +lsfe atomicrmw tests where the result is unused. (#132022)

Following the discussion on #131174, update generate-tests.py script to
emit atomicrmw tests where the result is unused and add a note to
explain why these do use ST[F]ADD.

3 files changed, 379 insertions, 4 deletions

diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64-atomicrmw-lsfe.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64-atomicrmw-lsfe.ll
index fc9a126..ef1f11e 100644
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64-atomicrmw-lsfe.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64-atomicrmw-lsfe.ll
@@ -3,6 +3,9 @@
 ; RUN: llc %s -o - -verify-machineinstrs -mtriple=aarch64 -mattr=+lsfe -O0 | FileCheck %s --check-prefixes=CHECK,-O0
 ; RUN: llc %s -o - -verify-machineinstrs -mtriple=aarch64 -mattr=+lsfe -O1 | FileCheck %s --check-prefixes=CHECK,-O1
 
+; NOTE: '_unused' tests are added to ensure we do not lower to ST[F]ADD when the destination register is WZR/XZR.
+; See discussion on https://github.com/llvm/llvm-project/pull/131174
+
 define dso_local half @atomicrmw_fadd_half_aligned_monotonic(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_monotonic:
 ; CHECK:    ldfadd h0, h0, [x0]
@@ -10,6 +13,13 @@ define dso_local half @atomicrmw_fadd_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fadd_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fadd_half_aligned_monotonic_unused:
+; CHECK:    ldfadd h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fadd_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_acquire:
 ; CHECK:    ldfadda h0, h0, [x0]
@@ -24,6 +34,13 @@ define dso_local half @atomicrmw_fadd_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fadd_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fadd_half_aligned_release_unused:
+; CHECK:    ldfaddl h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fadd_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_acq_rel:
 ; CHECK:    ldfaddal h0, h0, [x0]
@@ -45,6 +62,13 @@ define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fadd_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfadd h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_acquire:
 ; CHECK:    ldbfadda h0, h0, [x0]
@@ -59,6 +83,13 @@ define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fadd_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_release_unused:
+; CHECK:    ldbfaddl h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfaddal h0, h0, [x0]
@@ -80,6 +111,13 @@ define dso_local float @atomicrmw_fadd_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fadd_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fadd_float_aligned_monotonic_unused:
+; CHECK:    ldfadd s0, s0, [x0]
+    %r = atomicrmw fadd ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fadd_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fadd_float_aligned_acquire:
 ; CHECK:    ldfadda s0, s0, [x0]
@@ -94,6 +132,13 @@ define dso_local float @atomicrmw_fadd_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fadd_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fadd_float_aligned_release_unused:
+; CHECK:    ldfaddl s0, s0, [x0]
+    %r = atomicrmw fadd ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fadd_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fadd_float_aligned_acq_rel:
 ; CHECK:    ldfaddal s0, s0, [x0]
@@ -115,6 +160,13 @@ define dso_local double @atomicrmw_fadd_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fadd_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fadd_double_aligned_monotonic_unused:
+; CHECK:    ldfadd d0, d0, [x0]
+    %r = atomicrmw fadd ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fadd_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fadd_double_aligned_acquire:
 ; CHECK:    ldfadda d0, d0, [x0]
@@ -129,6 +181,13 @@ define dso_local double @atomicrmw_fadd_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fadd_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fadd_double_aligned_release_unused:
+; CHECK:    ldfaddl d0, d0, [x0]
+    %r = atomicrmw fadd ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fadd_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fadd_double_aligned_acq_rel:
 ; CHECK:    ldfaddal d0, d0, [x0]
@@ -805,6 +864,13 @@ define dso_local half @atomicrmw_fmax_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmax_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmax_half_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmax_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmax_half_aligned_acquire:
 ; CHECK:    ldfmaxnma h0, h0, [x0]
@@ -819,6 +885,13 @@ define dso_local half @atomicrmw_fmax_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmax_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmax_half_aligned_release_unused:
+; CHECK:    ldfmaxnml h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmax_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmax_half_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal h0, h0, [x0]
@@ -840,6 +913,13 @@ define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmax_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfmaxnm h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_acquire:
 ; CHECK:    ldbfmaxnma h0, h0, [x0]
@@ -854,6 +934,13 @@ define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmax_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_release_unused:
+; CHECK:    ldbfmaxnml h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfmaxnmal h0, h0, [x0]
@@ -875,6 +962,13 @@ define dso_local float @atomicrmw_fmax_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmax_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmax_float_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm s0, s0, [x0]
+    %r = atomicrmw fmax ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmax_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmax_float_aligned_acquire:
 ; CHECK:    ldfmaxnma s0, s0, [x0]
@@ -889,6 +983,13 @@ define dso_local float @atomicrmw_fmax_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmax_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmax_float_aligned_release_unused:
+; CHECK:    ldfmaxnml s0, s0, [x0]
+    %r = atomicrmw fmax ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmax_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmax_float_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal s0, s0, [x0]
@@ -910,6 +1011,13 @@ define dso_local double @atomicrmw_fmax_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmax_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmax_double_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm d0, d0, [x0]
+    %r = atomicrmw fmax ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmax_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmax_double_aligned_acquire:
 ; CHECK:    ldfmaxnma d0, d0, [x0]
@@ -924,6 +1032,13 @@ define dso_local double @atomicrmw_fmax_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmax_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmax_double_aligned_release_unused:
+; CHECK:    ldfmaxnml d0, d0, [x0]
+    %r = atomicrmw fmax ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmax_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmax_double_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal d0, d0, [x0]
@@ -1120,6 +1235,13 @@ define dso_local half @atomicrmw_fmin_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmin_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmin_half_aligned_monotonic_unused:
+; CHECK:    ldfminnm h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmin_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmin_half_aligned_acquire:
 ; CHECK:    ldfminnma h0, h0, [x0]
@@ -1134,6 +1256,13 @@ define dso_local half @atomicrmw_fmin_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmin_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmin_half_aligned_release_unused:
+; CHECK:    ldfminnml h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmin_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmin_half_aligned_acq_rel:
 ; CHECK:    ldfminnmal h0, h0, [x0]
@@ -1155,6 +1284,13 @@ define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmin_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfminnm h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_acquire:
 ; CHECK:    ldbfminnma h0, h0, [x0]
@@ -1169,6 +1305,13 @@ define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmin_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_release_unused:
+; CHECK:    ldbfminnml h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfminnmal h0, h0, [x0]
@@ -1190,6 +1333,13 @@ define dso_local float @atomicrmw_fmin_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmin_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmin_float_aligned_monotonic_unused:
+; CHECK:    ldfminnm s0, s0, [x0]
+    %r = atomicrmw fmin ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmin_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmin_float_aligned_acquire:
 ; CHECK:    ldfminnma s0, s0, [x0]
@@ -1204,6 +1354,13 @@ define dso_local float @atomicrmw_fmin_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmin_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmin_float_aligned_release_unused:
+; CHECK:    ldfminnml s0, s0, [x0]
+    %r = atomicrmw fmin ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmin_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmin_float_aligned_acq_rel:
 ; CHECK:    ldfminnmal s0, s0, [x0]
@@ -1225,6 +1382,13 @@ define dso_local double @atomicrmw_fmin_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmin_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmin_double_aligned_monotonic_unused:
+; CHECK:    ldfminnm d0, d0, [x0]
+    %r = atomicrmw fmin ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmin_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmin_double_aligned_acquire:
 ; CHECK:    ldfminnma d0, d0, [x0]
@@ -1239,6 +1403,13 @@ define dso_local double @atomicrmw_fmin_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmin_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmin_double_aligned_release_unused:
+; CHECK:    ldfminnml d0, d0, [x0]
+    %r = atomicrmw fmin ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmin_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmin_double_aligned_acq_rel:
 ; CHECK:    ldfminnmal d0, d0, [x0]
diff --git a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-atomicrmw-lsfe.ll b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-atomicrmw-lsfe.ll
index a22cc58..b43d6eb 100644
--- a/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-atomicrmw-lsfe.ll
+++ b/llvm/test/CodeGen/AArch64/Atomics/aarch64_be-atomicrmw-lsfe.ll
@@ -3,6 +3,9 @@
 ; RUN: llc %s -o - -verify-machineinstrs -mtriple=aarch64_be -mattr=+lsfe -O0 | FileCheck %s --check-prefixes=CHECK,-O0
 ; RUN: llc %s -o - -verify-machineinstrs -mtriple=aarch64_be -mattr=+lsfe -O1 | FileCheck %s --check-prefixes=CHECK,-O1
 
+; NOTE: '_unused' tests are added to ensure we do not lower to ST[F]ADD when the destination register is WZR/XZR.
+; See discussion on https://github.com/llvm/llvm-project/pull/131174
+
 define dso_local half @atomicrmw_fadd_half_aligned_monotonic(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_monotonic:
 ; CHECK:    ldfadd h0, h0, [x0]
@@ -10,6 +13,13 @@ define dso_local half @atomicrmw_fadd_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fadd_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fadd_half_aligned_monotonic_unused:
+; CHECK:    ldfadd h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fadd_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_acquire:
 ; CHECK:    ldfadda h0, h0, [x0]
@@ -24,6 +34,13 @@ define dso_local half @atomicrmw_fadd_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fadd_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fadd_half_aligned_release_unused:
+; CHECK:    ldfaddl h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fadd_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fadd_half_aligned_acq_rel:
 ; CHECK:    ldfaddal h0, h0, [x0]
@@ -45,6 +62,13 @@ define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fadd_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfadd h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_acquire:
 ; CHECK:    ldbfadda h0, h0, [x0]
@@ -59,6 +83,13 @@ define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fadd_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_release_unused:
+; CHECK:    ldbfaddl h0, h0, [x0]
+    %r = atomicrmw fadd ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fadd_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fadd_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfaddal h0, h0, [x0]
@@ -80,6 +111,13 @@ define dso_local float @atomicrmw_fadd_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fadd_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fadd_float_aligned_monotonic_unused:
+; CHECK:    ldfadd s0, s0, [x0]
+    %r = atomicrmw fadd ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fadd_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fadd_float_aligned_acquire:
 ; CHECK:    ldfadda s0, s0, [x0]
@@ -94,6 +132,13 @@ define dso_local float @atomicrmw_fadd_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fadd_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fadd_float_aligned_release_unused:
+; CHECK:    ldfaddl s0, s0, [x0]
+    %r = atomicrmw fadd ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fadd_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fadd_float_aligned_acq_rel:
 ; CHECK:    ldfaddal s0, s0, [x0]
@@ -115,6 +160,13 @@ define dso_local double @atomicrmw_fadd_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fadd_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fadd_double_aligned_monotonic_unused:
+; CHECK:    ldfadd d0, d0, [x0]
+    %r = atomicrmw fadd ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fadd_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fadd_double_aligned_acquire:
 ; CHECK:    ldfadda d0, d0, [x0]
@@ -129,6 +181,13 @@ define dso_local double @atomicrmw_fadd_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fadd_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fadd_double_aligned_release_unused:
+; CHECK:    ldfaddl d0, d0, [x0]
+    %r = atomicrmw fadd ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fadd_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fadd_double_aligned_acq_rel:
 ; CHECK:    ldfaddal d0, d0, [x0]
@@ -820,6 +879,13 @@ define dso_local half @atomicrmw_fmax_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmax_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmax_half_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmax_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmax_half_aligned_acquire:
 ; CHECK:    ldfmaxnma h0, h0, [x0]
@@ -834,6 +900,13 @@ define dso_local half @atomicrmw_fmax_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmax_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmax_half_aligned_release_unused:
+; CHECK:    ldfmaxnml h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmax_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmax_half_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal h0, h0, [x0]
@@ -855,6 +928,13 @@ define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmax_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfmaxnm h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_acquire:
 ; CHECK:    ldbfmaxnma h0, h0, [x0]
@@ -869,6 +949,13 @@ define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmax_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_release_unused:
+; CHECK:    ldbfmaxnml h0, h0, [x0]
+    %r = atomicrmw fmax ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmax_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmax_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfmaxnmal h0, h0, [x0]
@@ -890,6 +977,13 @@ define dso_local float @atomicrmw_fmax_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmax_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmax_float_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm s0, s0, [x0]
+    %r = atomicrmw fmax ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmax_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmax_float_aligned_acquire:
 ; CHECK:    ldfmaxnma s0, s0, [x0]
@@ -904,6 +998,13 @@ define dso_local float @atomicrmw_fmax_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmax_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmax_float_aligned_release_unused:
+; CHECK:    ldfmaxnml s0, s0, [x0]
+    %r = atomicrmw fmax ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmax_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmax_float_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal s0, s0, [x0]
@@ -925,6 +1026,13 @@ define dso_local double @atomicrmw_fmax_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmax_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmax_double_aligned_monotonic_unused:
+; CHECK:    ldfmaxnm d0, d0, [x0]
+    %r = atomicrmw fmax ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmax_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmax_double_aligned_acquire:
 ; CHECK:    ldfmaxnma d0, d0, [x0]
@@ -939,6 +1047,13 @@ define dso_local double @atomicrmw_fmax_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmax_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmax_double_aligned_release_unused:
+; CHECK:    ldfmaxnml d0, d0, [x0]
+    %r = atomicrmw fmax ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmax_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmax_double_aligned_acq_rel:
 ; CHECK:    ldfmaxnmal d0, d0, [x0]
@@ -1135,6 +1250,13 @@ define dso_local half @atomicrmw_fmin_half_aligned_monotonic(ptr %ptr, half %val
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmin_half_aligned_monotonic_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmin_half_aligned_monotonic_unused:
+; CHECK:    ldfminnm h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, half %value monotonic, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmin_half_aligned_acquire(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmin_half_aligned_acquire:
 ; CHECK:    ldfminnma h0, h0, [x0]
@@ -1149,6 +1271,13 @@ define dso_local half @atomicrmw_fmin_half_aligned_release(ptr %ptr, half %value
     ret half %r
 }
 
+define dso_local void @atomicrmw_fmin_half_aligned_release_unused(ptr %ptr, half %value) {
+; CHECK-LABEL: atomicrmw_fmin_half_aligned_release_unused:
+; CHECK:    ldfminnml h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, half %value release, align 2
+    ret void
+}
+
 define dso_local half @atomicrmw_fmin_half_aligned_acq_rel(ptr %ptr, half %value) {
 ; CHECK-LABEL: atomicrmw_fmin_half_aligned_acq_rel:
 ; CHECK:    ldfminnmal h0, h0, [x0]
@@ -1170,6 +1299,13 @@ define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_monotonic(ptr %ptr, bfloa
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmin_bfloat_aligned_monotonic_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_monotonic_unused:
+; CHECK:    ldbfminnm h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, bfloat %value monotonic, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_acquire(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_acquire:
 ; CHECK:    ldbfminnma h0, h0, [x0]
@@ -1184,6 +1320,13 @@ define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_release(ptr %ptr, bfloat
     ret bfloat %r
 }
 
+define dso_local void @atomicrmw_fmin_bfloat_aligned_release_unused(ptr %ptr, bfloat %value) {
+; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_release_unused:
+; CHECK:    ldbfminnml h0, h0, [x0]
+    %r = atomicrmw fmin ptr %ptr, bfloat %value release, align 2
+    ret void
+}
+
 define dso_local bfloat @atomicrmw_fmin_bfloat_aligned_acq_rel(ptr %ptr, bfloat %value) {
 ; CHECK-LABEL: atomicrmw_fmin_bfloat_aligned_acq_rel:
 ; CHECK:    ldbfminnmal h0, h0, [x0]
@@ -1205,6 +1348,13 @@ define dso_local float @atomicrmw_fmin_float_aligned_monotonic(ptr %ptr, float %
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmin_float_aligned_monotonic_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmin_float_aligned_monotonic_unused:
+; CHECK:    ldfminnm s0, s0, [x0]
+    %r = atomicrmw fmin ptr %ptr, float %value monotonic, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmin_float_aligned_acquire(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmin_float_aligned_acquire:
 ; CHECK:    ldfminnma s0, s0, [x0]
@@ -1219,6 +1369,13 @@ define dso_local float @atomicrmw_fmin_float_aligned_release(ptr %ptr, float %va
     ret float %r
 }
 
+define dso_local void @atomicrmw_fmin_float_aligned_release_unused(ptr %ptr, float %value) {
+; CHECK-LABEL: atomicrmw_fmin_float_aligned_release_unused:
+; CHECK:    ldfminnml s0, s0, [x0]
+    %r = atomicrmw fmin ptr %ptr, float %value release, align 4
+    ret void
+}
+
 define dso_local float @atomicrmw_fmin_float_aligned_acq_rel(ptr %ptr, float %value) {
 ; CHECK-LABEL: atomicrmw_fmin_float_aligned_acq_rel:
 ; CHECK:    ldfminnmal s0, s0, [x0]
@@ -1240,6 +1397,13 @@ define dso_local double @atomicrmw_fmin_double_aligned_monotonic(ptr %ptr, doubl
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmin_double_aligned_monotonic_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmin_double_aligned_monotonic_unused:
+; CHECK:    ldfminnm d0, d0, [x0]
+    %r = atomicrmw fmin ptr %ptr, double %value monotonic, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmin_double_aligned_acquire(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmin_double_aligned_acquire:
 ; CHECK:    ldfminnma d0, d0, [x0]
@@ -1254,6 +1418,13 @@ define dso_local double @atomicrmw_fmin_double_aligned_release(ptr %ptr, double
     ret double %r
 }
 
+define dso_local void @atomicrmw_fmin_double_aligned_release_unused(ptr %ptr, double %value) {
+; CHECK-LABEL: atomicrmw_fmin_double_aligned_release_unused:
+; CHECK:    ldfminnml d0, d0, [x0]
+    %r = atomicrmw fmin ptr %ptr, double %value release, align 8
+    ret void
+}
+
 define dso_local double @atomicrmw_fmin_double_aligned_acq_rel(ptr %ptr, double %value) {
 ; CHECK-LABEL: atomicrmw_fmin_double_aligned_acq_rel:
 ; CHECK:    ldfminnmal d0, d0, [x0]
diff --git a/llvm/test/CodeGen/AArch64/Atomics/generate-tests.py b/llvm/test/CodeGen/AArch64/Atomics/generate-tests.py
index f40bbae..24d1ef1 100755
--- a/llvm/test/CodeGen/AArch64/Atomics/generate-tests.py
+++ b/llvm/test/CodeGen/AArch64/Atomics/generate-tests.py
@@ -189,19 +189,29 @@ def relpath():
     return fp
 
 
+def generate_unused_res_test(featname, ordering, op, alignval):
+    if featname != "lsfe" or op == "fsub" or alignval == 1:
+        return False
+    if ordering not in [AtomicOrder.monotonic, AtomicOrder.release]:
+        return False
+    return True
+
+
 def align(val, aligned: bool) -> int:
     return val if aligned else 1
 
 
-def all_atomicrmw(f, datatype, atomicrmw_ops):
+def all_atomicrmw(f, datatype, atomicrmw_ops, featname):
+    instr = "atomicrmw"
+    generate_unused = False
+    tests = []
     for op in atomicrmw_ops:
         for aligned in Aligned:
             for ty, val in datatype:
                 alignval = align(val, aligned)
                 for ordering in ATOMICRMW_ORDERS:
                     name = f"atomicrmw_{op}_{ty}_{aligned}_{ordering}"
-                    instr = "atomicrmw"
-                    f.write(
+                    tests.append(
                         textwrap.dedent(
                             f"""
                         define dso_local {ty} @{name}(ptr %ptr, {ty} %value) {{
@@ -211,6 +221,29 @@ def all_atomicrmw(f, datatype, atomicrmw_ops):
                     """
                         )
                     )
+                    if generate_unused_res_test(featname, ordering, op, alignval):
+                        generate_unused = True
+                        name = f"atomicrmw_{op}_{ty}_{aligned}_{ordering}_unused"
+                        tests.append(
+                            textwrap.dedent(
+                                f"""
+                           define dso_local void @{name}(ptr %ptr, {ty} %value) {{
+                               %r = {instr} {op} ptr %ptr, {ty} %value {ordering}, align {alignval}
+                               ret void
+                           }}
+                        """
+                            )
+                        )
+
+    if generate_unused:
+        f.write(
+            "\n; NOTE: '_unused' tests are added to ensure we do not lower to "
+            "ST[F]ADD when the destination register is WZR/XZR.\n"
+            "; See discussion on https://github.com/llvm/llvm-project/pull/131174\n"
+        )
+
+    for test in tests:
+        f.write(test)
 
 
 def all_load(f):
@@ -340,7 +373,7 @@ def write_lit_tests(feature, datatypes, ops):
             with open(f"{triple}-atomicrmw-{feat.name}.ll", "w") as f:
                 filter_args = r'--filter-out "\b(sp)\b" --filter "^\s*(ld[^r]|st[^r]|swp|cas|bl|add|and|eor|orn|orr|sub|mvn|sxt|cmp|ccmp|csel|dmb)"'
                 header(f, triple, [feat], filter_args)
-                all_atomicrmw(f, datatypes, ops)
+                all_atomicrmw(f, datatypes, ops, feat.name)
 
             # Floating point atomics only supported for atomicrmw currently
             if feature.test_scope() == "atomicrmw":