1 files changed, 41 insertions, 0 deletions
diff --git a/test/CodeGen/X86/tail-merge-identical.ll b/test/CodeGen/X86/tail-merge-identical.ll
new file mode 100644
index 000000000000..024ad582d03f
--- /dev/null
+++ b/test/CodeGen/X86/tail-merge-identical.ll
@@ -0,0 +1,41 @@
+; RUN: llc -o - -verify-machineinstrs %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@data = external global [3 x i32], align 4
+@store = external global i32, align 4
+
+; %else1 and %then2 end up lowering to identical blocks. These blocks should be
+; merged during tail-merging.
+; CHECK-LABEL: merge_identical_blocks
+; CHECK: movl $data+4
+; CHECK-NOT: movl $data+4
+; CHECK: retq
+define void @merge_identical_blocks(i1 %a, i1 %b) {
+entry:
+  br label %if1
+
+if1:                                              ; predfs = %entry
+  br i1 %a, label %else1, label %if2
+
+else1:                                            ; preds = %if1
+  %ptr.else1 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 1
+  br label %phi_join
+
+if2:                                              ; preds = %if1
+  br i1 %b, label %then2, label %else2
+
+then2:                                            ; preds = %if2
+  %ptr.then2 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 1
+  br label %phi_join
+
+else2:                                            ; preds = %if2
+  %ptr.else2 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 2
+  br label %phi_join
+
+phi_join:                                         ; preds = %else1, %then2, %else2
+  %val.ptr = phi i32* [ %ptr.else1, %else1 ], [ %ptr.then2, %then2 ], [ %ptr.else2, %else2 ]
+  %val = load i32, i32* %val.ptr, align 4
+  store i32 %val, i32* @store, align 4
+  ret void
+}