Index: llvm/test/Transforms/GVN/condprop.ll
===================================================================
--- llvm/test/Transforms/GVN/condprop.ll
+++ llvm/test/Transforms/GVN/condprop.ll
@@ -512,9 +512,7 @@
   ret i32 %res
 }
 
-; On the path from entry->if->end we know that ptr1==ptr2, so we can determine
-; that gep2 does not alias ptr1 on that path (as it would require that
-; ptr2==ptr2+2), so we can perform PRE of the load.
+; Check that we dont propagate pointer equalities when illegal.
 define i32 @test13(ptr %ptr1, ptr %ptr2) {
 ; CHECK-LABEL: @test13(
 ; CHECK-NEXT:  entry:
@@ -556,14 +554,14 @@
   ret i32 %ret
 }
 
-define void @test14(ptr %ptr1, ptr noalias %ptr2) {
+define void @test14(ptr %ptr1, ptr noalias %ptr2, i1 %c1, i1 %c2) {
 ; CHECK-LABEL: @test14(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[PTR1:%.*]], i32 1
 ; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr inbounds i32, ptr [[PTR1]], i32 2
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    br i1 undef, label [[LOOP_IF1_CRIT_EDGE:%.*]], label [[THEN:%.*]]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[LOOP_IF1_CRIT_EDGE:%.*]], label [[THEN:%.*]]
 ; CHECK:       loop.if1_crit_edge:
 ; CHECK-NEXT:    [[VAL2_PRE:%.*]] = load i32, ptr [[GEP2]], align 4
 ; CHECK-NEXT:    br label [[IF1:%.*]]
@@ -581,7 +579,7 @@
 ; CHECK-NEXT:    [[PHI3:%.*]] = phi ptr [ [[PTR2]], [[THEN]] ], [ [[PTR1]], [[IF2]] ]
 ; CHECK-NEXT:    [[VAL3]] = load i32, ptr [[GEP2]], align 4
 ; CHECK-NEXT:    store i32 [[VAL3]], ptr [[PHI3]], align 4
-; CHECK-NEXT:    br i1 undef, label [[LOOP]], label [[IF1]]
+; CHECK-NEXT:    br i1 [[C2:%.*]], label [[LOOP]], label [[IF1]]
 ;
 entry:
   %gep1 = getelementptr inbounds i32, ptr %ptr1, i32 1
@@ -590,7 +588,7 @@
 
 loop:
   %phi1 = phi ptr [ %gep3, %loop.end ], [ %gep1, %entry ]
-  br i1 undef, label %if1, label %then
+  br i1 %c1, label %if1, label %then
 
 
 if1:
@@ -611,5 +609,204 @@
   %val3 = load i32, ptr %gep2, align 4
   store i32 %val3, ptr %phi3, align 4
   %gep3 = getelementptr inbounds i32, ptr %ptr1, i32 1
-  br i1 undef, label %loop, label %if1
+  br i1 %c2, label %loop, label %if1
 }
+
+define void @single_phi1(ptr %p1) {
+; CHECK-LABEL: @single_phi1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr poison, align 8
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq ptr [[P2]], [[P1:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[BB4:%.*]], label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    switch i8 poison, label [[BB2:%.*]] [
+; CHECK-NEXT:    i8 0, label [[BB1]]
+; CHECK-NEXT:    i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       bb2:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb3:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb4:
+; CHECK-NEXT:    call void @use_bool(i1 true)
+; CHECK-NEXT:    call void @use_ptr(ptr [[P1]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %p2 = load ptr, ptr poison, align 8
+  %cmp1 = icmp eq ptr %p2, %p1
+  br i1 %cmp1, label %bb4, label %bb1
+
+bb1:
+  switch i8 poison, label %bb2 [
+  i8 0, label %bb1
+  i8 1, label %bb3
+  ]
+
+bb2:
+  unreachable
+
+bb3:
+  br label %bb4
+
+bb4:
+  %phi1 = phi ptr [ %p2, %entry ], [ poison, %bb3 ]
+  %cmp2 = icmp eq ptr %phi1, %p1
+  call void @use_bool(i1 %cmp2)
+  call void @use_ptr(ptr %phi1)
+  ret void
+}
+
+define void @single_phi2(ptr %p1) {
+; CHECK-LABEL: @single_phi2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr poison, align 8
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq ptr [[P2]], [[P1:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[BB4:%.*]], label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    switch i8 poison, label [[BB2:%.*]] [
+; CHECK-NEXT:    i8 0, label [[BB1]]
+; CHECK-NEXT:    i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb3:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb4:
+; CHECK-NEXT:    [[PHI1:%.*]] = phi ptr [ [[P1]], [[ENTRY:%.*]] ], [ [[P2]], [[BB2]] ], [ poison, [[BB3]] ]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq ptr [[PHI1]], [[P1]]
+; CHECK-NEXT:    call void @use_bool(i1 [[CMP2]])
+; CHECK-NEXT:    call void @use_ptr(ptr [[PHI1]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %p2 = load ptr, ptr poison, align 8
+  %cmp1 = icmp eq ptr %p2, %p1
+  br i1 %cmp1, label %bb4, label %bb1
+
+bb1:
+  switch i8 poison, label %bb2 [
+  i8 0, label %bb1
+  i8 1, label %bb3
+  ]
+
+bb2:
+  br label %bb4
+
+bb3:
+  br label %bb4
+
+bb4:
+  %phi1 = phi ptr [ %p2, %entry ], [ %p2, %bb2 ], [ poison, %bb3 ]
+  %cmp2 = icmp eq ptr %phi1, %p1
+  call void @use_bool(i1 %cmp2)
+  call void @use_ptr(ptr %phi1)
+  ret void
+}
+
+define void @multiple_phi1(ptr %p1) {
+; CHECK-LABEL: @multiple_phi1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr poison, align 8
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq ptr [[P2]], [[P1:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[BB4:%.*]], label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    switch i8 poison, label [[BB2:%.*]] [
+; CHECK-NEXT:    i8 0, label [[BB1]]
+; CHECK-NEXT:    i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       bb2:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb3:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb4:
+; CHECK-NEXT:    call void @use_bool(i1 true)
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       bb5:
+; CHECK-NEXT:    call void @use_ptr(ptr [[P1]])
+; CHECK-NEXT:    br label [[BB5]]
+;
+entry:
+  %p2 = load ptr, ptr poison, align 8
+  %cmp1 = icmp eq ptr %p2, %p1
+  br i1 %cmp1, label %bb4, label %bb1
+
+bb1:
+  switch i8 poison, label %bb2 [
+  i8 0, label %bb1
+  i8 1, label %bb3
+  ]
+
+bb2:
+  unreachable
+
+bb3:
+  br label %bb4
+
+bb4:
+  %phi1 = phi ptr [ %p2, %entry ], [ poison, %bb3 ]
+  %cmp2 = icmp eq ptr %phi1, %p1
+  call void @use_bool(i1 %cmp2)
+  br label %bb5
+
+bb5:
+  %phi2 = phi ptr [ poison, %bb5 ], [ %phi1, %bb4 ]
+  call void @use_ptr(ptr %phi2)
+  br label %bb5
+}
+
+define void @multiple_phi2(ptr %p1) {
+; CHECK-LABEL: @multiple_phi2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr poison, align 8
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq ptr [[P2]], [[P1:%.*]]
+; CHECK-NEXT:    br i1 [[CMP1]], label [[BB4:%.*]], label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    switch i8 poison, label [[BB2:%.*]] [
+; CHECK-NEXT:    i8 0, label [[BB1]]
+; CHECK-NEXT:    i8 1, label [[BB3:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb3:
+; CHECK-NEXT:    br label [[BB4]]
+; CHECK:       bb4:
+; CHECK-NEXT:    [[PHI1:%.*]] = phi ptr [ [[P1]], [[ENTRY:%.*]] ], [ [[P2]], [[BB2]] ], [ poison, [[BB3]] ]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq ptr [[PHI1]], [[P1]]
+; CHECK-NEXT:    call void @use_bool(i1 [[CMP2]])
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       bb5:
+; CHECK-NEXT:    call void @use_ptr(ptr [[PHI1]])
+; CHECK-NEXT:    br label [[BB5]]
+;
+entry:
+  %p2 = load ptr, ptr poison, align 8
+  %cmp1 = icmp eq ptr %p2, %p1
+  br i1 %cmp1, label %bb4, label %bb1
+
+bb1:
+  switch i8 poison, label %bb2 [
+  i8 0, label %bb1
+  i8 1, label %bb3
+  ]
+
+bb2:
+  br label %bb4
+
+bb3:
+  br label %bb4
+
+bb4:
+  %phi1 = phi ptr [ %p2, %entry ], [ %p2, %bb2 ], [ poison, %bb3 ]
+  %cmp2 = icmp eq ptr %phi1, %p1
+  call void @use_bool(i1 %cmp2)
+  br label %bb5
+
+bb5:
+  %phi2 = phi ptr [ poison, %bb5 ], [ %phi1, %bb4 ]
+  call void @use_ptr(ptr %phi2)
+  br label %bb5
+}
+
+declare void @use_bool(i1)
+declare void @use_ptr(ptr)