Index: llvm/trunk/test/Transforms/MergeICmps/X86/alias-merge-blocks.ll
===================================================================
--- llvm/trunk/test/Transforms/MergeICmps/X86/alias-merge-blocks.ll
+++ llvm/trunk/test/Transforms/MergeICmps/X86/alias-merge-blocks.ll
@@ -0,0 +1,66 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -mtriple=x86_64-unknown-unknown -mergeicmps -S | FileCheck %s --check-prefix=X86
+
+%"struct.std::pair" = type { i32, i32, i32, i32 }
+
+; Before patch D51550
+define zeroext i1 @opeq1(
+; X86-LABEL: @opeq1(
+; X86-NEXT:  entry:
+; X86-NEXT:    [[PTR:%.*]] = alloca i32
+; X86-NEXT:    [[FIRST_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A:%.*]], i64 0, i32 0
+; X86-NEXT:    [[TMP0:%.*]] = load i32, i32* [[FIRST_I]], align 4
+; X86-NEXT:    [[FIRST1_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B:%.*]], i64 0, i32 0
+; X86-NEXT:    [[TMP1:%.*]] = load i32, i32* [[FIRST1_I]], align 4
+; X86-NEXT:    store i32 42, i32* [[PTR]]
+; X86-NEXT:    [[CMP_I:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
+; X86-NEXT:    br i1 [[CMP_I]], label [[LAND_RHS_I:%.*]], label [[OPEQ1_EXIT:%.*]]
+; X86:       land.rhs.i:
+; X86-NEXT:    [[SECOND_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A]], i64 0, i32 1
+; X86-NEXT:    [[TMP2:%.*]] = load i32, i32* [[SECOND_I]], align 4
+; X86-NEXT:    [[SECOND2_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B]], i64 0, i32 1
+; X86-NEXT:    [[TMP3:%.*]] = load i32, i32* [[SECOND2_I]], align 4
+; X86-NEXT:    [[CMP2_I:%.*]] = icmp eq i32 [[TMP2]], [[TMP3]]
+; X86-NEXT:    br i1 [[CMP2_I]], label [[LAND_RHS_I_2:%.*]], label [[OPEQ1_EXIT]]
+
+  %"struct.std::pair"* nocapture readonly dereferenceable(16) %a,
+  %"struct.std::pair"* nocapture readonly dereferenceable(16) %b) local_unnamed_addr #0 {
+entry:
+  %ptr = alloca i32
+  %first.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 0
+  %0 = load i32, i32* %first.i, align 4
+  %first1.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 0
+  %1 = load i32, i32* %first1.i, align 4
+  ; Does other work, has no interference, merge block
+  store i32 42, i32* %ptr
+  %cmp.i = icmp eq i32 %0, %1
+  br i1 %cmp.i, label %land.rhs.i, label %opeq1.exit
+
+land.rhs.i:
+  %second.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 1
+  %2 = load i32, i32* %second.i, align 4
+  %second2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 1
+  %3 = load i32, i32* %second2.i, align 4
+  %cmp2.i = icmp eq i32 %2, %3
+  br i1 %cmp2.i, label %land.rhs.i.2, label %opeq1.exit
+
+land.rhs.i.2:
+  %third.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 2
+  %4 = load i32, i32* %third.i, align 4
+  %third2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 2
+  %5 = load i32, i32* %third2.i, align 4
+  %cmp3.i = icmp eq i32 %4, %5
+  br i1 %cmp3.i, label %land.rhs.i.3, label %opeq1.exit
+
+land.rhs.i.3:
+  %fourth.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %a, i64 0, i32 3
+  %6 = load i32, i32* %fourth.i, align 4
+  %fourth2.i = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* %b, i64 0, i32 3
+  %7 = load i32, i32* %fourth2.i, align 4
+  %cmp4.i = icmp eq i32 %6, %7
+  br label %opeq1.exit
+
+opeq1.exit:
+  %8 = phi i1 [ false, %entry ], [ false, %land.rhs.i] , [ false, %land.rhs.i.2 ], [ %cmp4.i, %land.rhs.i.3 ]
+  ret i1 %8
+}