add comments to test

Author: OCHyams

llvm/test/DebugInfo/KeyInstructions/Generic/loop-unswitch.ll

@@ -1,4 +1,3 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt %s -S --passes="loop-mssa(simple-loop-unswitch<nontrivial>)" -o - \
 ; RUN: | FileCheck %s
 
@@ -27,26 +26,42 @@
 
 ; CHECK-LABEL: define i32 @partial_unswitch_true_successor_hoist_invariant(
 ; CHECK-SAME: ptr [[PTR:%.*]], i32 [[N:%.*]]) !dbg [[DBG5:![0-9]+]] {
+
+;; Instructions duplicated from loop.header need remapped atoms.
 ; CHECK-NEXT:  [[ENTRY:.*:]]
 ; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr i32, ptr [[PTR]], i64 1, !dbg [[DBG8:![0-9]+]]
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i32, ptr [[TMP0]], align 4, !dbg [[DBG9:![0-9]+]]
 ; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 100, !dbg [[DBG10:![0-9]+]]
 ; CHECK-NEXT:    br i1 [[TMP2]], label %[[ENTRY_SPLIT_US:.*]], label %[[ENTRY_SPLIT:.*]]
+
+;; Same source location as entry's original br, with remapped atom group.
 ; CHECK:       [[ENTRY_SPLIT_US]]:
 ; CHECK-NEXT:    br label %[[LOOP_HEADER_US:.*]], !dbg [[DBG11:![0-9]+]]
+
+;; Instructions duplicated from loop.header need remapped atoms.
 ; CHECK:       [[LOOP_HEADER_US]]:
 ; CHECK-NEXT:    [[IV_US:%.*]] = phi i32 [ 0, %[[ENTRY_SPLIT_US]] ], [ [[IV_NEXT_US:%.*]], %[[LOOP_LATCH_US:.*]] ], !dbg [[DBG12:![0-9]+]]
 ; CHECK-NEXT:    br label %[[NOCLOBBER_US:.*]], !dbg [[DBG13:![0-9]+]]
+
+;; Instructions duplicated from noclobber need remapped atoms.
 ; CHECK:       [[NOCLOBBER_US]]:
 ; CHECK-NEXT:    br label %[[LOOP_LATCH_US]], !dbg [[DBG14:![0-9]+]]
+
 ; CHECK:       [[LOOP_LATCH_US]]:
 ; CHECK-NEXT:    [[C_US:%.*]] = icmp ult i32 [[IV_US]], [[N]], !dbg [[DBG15:![0-9]+]]
 ; CHECK-NEXT:    [[IV_NEXT_US]] = add i32 [[IV_US]], 1, !dbg [[DBG16:![0-9]+]]
 ; CHECK-NEXT:    br i1 [[C_US]], label %[[LOOP_HEADER_US]], label %[[EXIT_SPLIT_US:.*]], !dbg [[DBG17:![0-9]+]]
+
+;; Split from exit, this DILocation shouldn't have source atom info.
 ; CHECK:       [[EXIT_SPLIT_US]]:
 ; CHECK-NEXT:    br label %[[EXIT:.*]], !dbg [[DBG18:![0-9]+]]
+
+;; Same source location as entry's original br, with remapped atom group.
 ; CHECK:       [[ENTRY_SPLIT]]:
 ; CHECK-NEXT:    br label %[[LOOP_HEADER:.*]], !dbg [[DBG19:![0-9]+]]
+
+;; Original loop blocks - the atoms groups should be distinct from those
+;; on duplicated instructions in the blocks above.
 ; CHECK:       [[LOOP_HEADER]]:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, %[[ENTRY_SPLIT]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ], !dbg [[DBG20:![0-9]+]]
 ; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i32, ptr [[PTR]], i64 1, !dbg [[DBG21:![0-9]+]]
@@ -61,9 +76,14 @@
 ; CHECK:       [[LOOP_LATCH]]:
 ; CHECK-NEXT:    [[C:%.*]] = icmp ult i32 [[IV]], [[N]], !dbg [[DBG28:![0-9]+]]
 ; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1, !dbg [[DBG29:![0-9]+]]
-; CHECK-NEXT:    br i1 [[C]], label %[[LOOP_HEADER]], label %[[EXIT_SPLIT:.*]], !dbg [[DBG30:![0-9]+]], !llvm.loop [[LOOP31:![0-9]+]]
+; CHECK-NEXT:    br i1 [[C]], label %[[LOOP_HEADER]], label %[[EXIT_SPLIT:.*]], !dbg [[DBG30:![0-9]+]]
+
+;; Split from exit, this DILocation shouldn't have source atom info.
 ; CHECK:       [[EXIT_SPLIT]]:
 ; CHECK-NEXT:    br label %[[EXIT]], !dbg [[DBG18]]
+
+;; exit.split and exit.split.us take the source location from here but drop its
+;; source atom info.
 ; CHECK:       [[EXIT]]:
 ; CHECK-NEXT:    ret i32 10, !dbg [[DBG33:![0-9]+]]