[NFC][GVN] Add a (horrible) test for D84181 demonstrating non-NFC'ness

llvm/test/Transforms/GVN/loadpre-missed-opportunity.ll

@@ -0,0 +1,62 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -gvn -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @use(i32*)
+
+define dso_local void @_Z2axv(i32** %arg, i1 %arg1, i1 %arg2, i1 %arg3) local_unnamed_addr {
+; CHECK-LABEL: @_Z2axv(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    br label [[BB9:%.*]]
+; CHECK:       bb6:
+; CHECK-NEXT:    br label [[BB9]]
+; CHECK:       bb9:
+; CHECK-NEXT:    br i1 [[ARG1:%.*]], label [[BB6:%.*]], label [[BB10:%.*]]
+; CHECK:       bb10:
+; CHECK-NEXT:    [[I11:%.*]] = tail call i32* @zzz()
+; CHECK-NEXT:    br i1 [[ARG2:%.*]], label [[BB12:%.*]], label [[BB15:%.*]]
+; CHECK:       bb12:
+; CHECK-NEXT:    br label [[BB13:%.*]]
+; CHECK:       bb13:
+; CHECK-NEXT:    br i1 [[ARG3:%.*]], label [[BB14:%.*]], label [[BB13]]
+; CHECK:       bb14:
+; CHECK-NEXT:    br label [[BB15]]
+; CHECK:       bb15:
+; CHECK-NEXT:    br label [[BB6]]
+;
+bb:
+  %i = load i32*, i32** %arg, align 8
+  %i4 = getelementptr inbounds i32, i32* %i, i64 0
+  br label %bb5
+
+bb5:                                              ; preds = %bb
+  br label %bb9
+
+bb6:                                              ; preds = %bb15, %bb9
+  %i7 = load i32*, i32** %arg, align 8
+  %i8 = getelementptr inbounds i32, i32* %i7, i64 0
+  br label %bb9
+
+bb9:                                              ; preds = %bb6, %bb5
+  br i1 %arg1, label %bb6, label %bb10
+
+bb10:                                             ; preds = %bb9
+  %i11 = tail call i32* @zzz()
+  br i1 %arg2, label %bb12, label %bb15
+
+bb12:                                             ; preds = %bb10
+  br label %bb13
+
+bb13:                                             ; preds = %bb13, %bb12
+  br i1 %arg3, label %bb14, label %bb13
+
+bb14:                                             ; preds = %bb13
+  br label %bb15
+
+bb15:                                             ; preds = %bb14, %bb10
+  br label %bb6
+}
+
+declare dso_local i32* @zzz() local_unnamed_addr