Add test

Author: arsenm

llvm/test/CodeGen/AArch64/machine-combiner-subregs.mir

@@ -0,0 +1,35 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
+# RUN: llc -mtriple=aarch64-gnu-linux -mcpu=neoverse-n2 -run-pass=machine-combiner -o - %s | FileCheck %s
+
+# Make sure machine combiner doesn't drop subregister indexes.
+
+---
+name:            reassociate_adds2_reassoc
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $q0, $q1, $q2, $q3
+
+    ; CHECK-LABEL: name: reassociate_adds2_reassoc
+    ; CHECK: liveins: $q0, $q1, $q2, $q3
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:fpr128 = COPY $q0
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:fpr128 = COPY $q1
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:fpr128 = COPY $q2
+    ; CHECK-NEXT: [[COPY3:%[0-9]+]]:fpr128 = COPY $q3
+    ; CHECK-NEXT: [[FADDSrr:%[0-9]+]]:fpr32 = nsz reassoc nofpexcept FADDSrr [[COPY]].ssub, [[COPY1]].ssub, implicit $fpcr
+    ; CHECK-NEXT: [[FADDSrr1:%[0-9]+]]:fpr32 = nsz reassoc nofpexcept FADDSrr [[COPY2]].ssub, [[COPY3]].ssub, implicit $fpcr
+    ; CHECK-NEXT: [[FADDSrr2:%[0-9]+]]:fpr32 = nsz reassoc nofpexcept FADDSrr killed [[FADDSrr1]], killed [[FADDSrr]], implicit $fpcr
+    ; CHECK-NEXT: $s0 = COPY [[FADDSrr2]]
+    ; CHECK-NEXT: RET_ReallyLR implicit $s0
+    %0:fpr128 = COPY $q0
+    %1:fpr128 = COPY $q1
+    %2:fpr128 = COPY $q2
+    %3:fpr128 = COPY $q3
+    %4:fpr32 = nsz reassoc nofpexcept FADDSrr %0.ssub, %1.ssub, implicit $fpcr
+    %5:fpr32 = nsz reassoc nofpexcept FADDSrr %2.ssub, killed %4, implicit $fpcr
+    %6:fpr32 = nsz reassoc nofpexcept FADDSrr killed %5, %3.ssub, implicit $fpcr
+    $s0 = COPY %6
+    RET_ReallyLR implicit $s0
+
+...