From 0a87e53fc40ffd644139cdd210e7c382dbe329c8 Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Tue, 5 Jan 2021 22:01:22 +0300
Subject: [PATCH] [NFC][SimplifyCFG] Add a test where
 SimplifyEqualityComparisonWithOnlyPredecessor() deletes existing edge

---
 ...nlyPredecessor-domtree-preservation-edgecase.ll | 51 ++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 llvm/test/Transforms/SimplifyCFG/SimplifyEqualityComparisonWithOnlyPredecessor-domtree-preservation-edgecase.ll

diff --git a/llvm/test/Transforms/SimplifyCFG/SimplifyEqualityComparisonWithOnlyPredecessor-domtree-preservation-edgecase.ll b/llvm/test/Transforms/SimplifyCFG/SimplifyEqualityComparisonWithOnlyPredecessor-domtree-preservation-edgecase.ll
new file mode 100644
index 0000000..d6b9ea7
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/SimplifyEqualityComparisonWithOnlyPredecessor-domtree-preservation-edgecase.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=0 < %s | FileCheck %s
+
+declare void @zzz()
+
+define i32 @lex(i1 %c0, i1 %c1, i32 %r0, i32 %r1, i32 %v) {
+; CHECK-LABEL: @lex(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[C0_NOT:%.*]] = xor i1 [[C0:%.*]], true
+; CHECK-NEXT:    [[C1_NOT:%.*]] = xor i1 [[C1:%.*]], true
+; CHECK-NEXT:    [[BRMERGE:%.*]] = or i1 [[C0_NOT]], [[C1_NOT]]
+; CHECK-NEXT:    [[R0_MUX:%.*]] = select i1 [[C0_NOT]], i32 [[R0:%.*]], i32 [[R1:%.*]]
+; CHECK-NEXT:    br i1 [[BRMERGE]], label [[IF_THEN:%.*]], label [[DO_BODY:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    [[MERGE:%.*]] = phi i32 [ [[R0_MUX]], [[ENTRY:%.*]] ], [ [[R1]], [[DO_BODY]] ]
+; CHECK-NEXT:    ret i32 [[MERGE]]
+; CHECK:       do.body:
+; CHECK-NEXT:    call void @zzz()
+; CHECK-NEXT:    switch i32 [[V:%.*]], label [[IF_THEN]] [
+; CHECK-NEXT:    i32 10, label [[DO_BODY]]
+; CHECK-NEXT:    i32 32, label [[DO_BODY]]
+; CHECK-NEXT:    i32 9, label [[DO_BODY]]
+; CHECK-NEXT:    ]
+;
+entry:
+  br i1 %c0, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  ret i32 %r0
+
+if.end:                                           ; preds = %entry
+  br i1 %c1, label %do.body, label %do.end
+
+do.body:                                          ; preds = %if.then193, %if.then193, %if.then193, %do.body, %do.body, %if.end
+  call void @zzz()
+  switch i32 %v, label %do.end [
+  i32 10, label %if.then193
+  i32 32, label %do.body
+  i32 9, label %do.body
+  ]
+
+if.then193:                                       ; preds = %do.body
+  switch i32 %v, label %do.end [
+  i32 32, label %do.body
+  i32 10, label %do.body
+  i32 9, label %do.body
+  ]
+
+do.end:                                           ; preds = %if.then193, %do.body, %if.end
+  ret i32 %r1
+}
-- 
2.7.4