1 files changed, 112 insertions, 0 deletions
diff --git a/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll b/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
index 3687327..81079b1 100644
--- a/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
+++ b/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
@@ -806,3 +806,115 @@ return:
 ; CHECK-NOT: @switch.table
 ; CHECK: switch i32 %c
 }
+
+; If we can build a lookup table without any holes, we don't need a default result.
+declare void @exit(i32)
+define i32 @nodefaultnoholes(i32 %c) {
+entry:
+  switch i32 %c, label %sw.default [
+    i32 0, label %return
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+    i32 3, label %sw.bb3
+  ]
+
+sw.bb1: br label %return
+sw.bb2: br label %return
+sw.bb3: br label %return
+sw.default: call void @exit(i32 1)
+            unreachable
+return:
+  %x = phi i32 [ -1, %sw.bb3 ], [ 0, %sw.bb2 ], [ 123, %sw.bb1 ], [ 55, %entry ]
+  ret i32 %x
+
+; CHECK-LABEL: @nodefaultnoholes(
+; CHECK: @switch.table
+; CHECK-NOT: switch i32
+}
+
+; This lookup table will have holes, so we need to test for the holes.
+define i32 @nodefaultwithholes(i32 %c) {
+entry:
+  switch i32 %c, label %sw.default [
+    i32 0, label %return
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+    i32 3, label %sw.bb3
+    i32 5, label %sw.bb3
+  ]
+
+sw.bb1: br label %return
+sw.bb2: br label %return
+sw.bb3: br label %return
+sw.default: call void @exit(i32 1)
+            unreachable
+return:
+  %x = phi i32 [ -1, %sw.bb3 ], [ 0, %sw.bb2 ], [ 123, %sw.bb1 ], [ 55, %entry ]
+  ret i32 %x
+
+; CHECK-LABEL: @nodefaultwithholes(
+; CHECK: entry:
+; CHECK: br i1 %{{.*}}, label %switch.hole_check, label %sw.default
+; CHECK: switch.hole_check:
+; CHECK-NEXT: %switch.maskindex = trunc i32 %switch.tableidx to i6
+; CHECK-NEXT: %switch.shifted = lshr i6 -17, %switch.maskindex
+; The mask is binary 101111.
+; CHECK-NEXT: %switch.lobit = trunc i6 %switch.shifted to i1
+; CHECK-NEXT: br i1 %switch.lobit, label %switch.lookup, label %sw.default
+; CHECK-NOT: switch i32
+}
+
+; We don't build lookup tables with holes for switches with less than four cases.
+define i32 @threecasesholes(i32 %c) {
+entry:
+  switch i32 %c, label %sw.default [
+    i32 0, label %return
+    i32 1, label %sw.bb1
+    i32 3, label %sw.bb2
+  ]
+sw.bb1: br label %return
+sw.bb2: br label %return
+sw.default: br label %return
+return:
+  %x = phi i32 [ %c, %sw.default ], [ 5, %sw.bb2 ], [ 7, %sw.bb1 ], [ 9, %entry ]
+  ret i32 %x
+; CHECK-LABEL: @threecasesholes(
+; CHECK: switch i32
+; CHECK-NOT: @switch.table
+}
+
+; We build lookup tables for switches with three or more cases.
+define i32 @threecases(i32 %c) {
+entry:
+  switch i32 %c, label %sw.default [
+    i32 0, label %return
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+  ]
+sw.bb1: br label %return
+sw.bb2: br label %return
+sw.default: br label %return
+return:
+  %x = phi i32 [ 3, %sw.default ], [ 5, %sw.bb2 ], [ 7, %sw.bb1 ], [ 9, %entry ]
+  ret i32 %x
+; CHECK-LABEL: @threecases(
+; CHECK-NOT: switch i32
+; CHECK: @switch.table
+}
+
+; We don't build tables for switches with two cases.
+define i32 @twocases(i32 %c) {
+entry:
+  switch i32 %c, label %sw.default [
+    i32 0, label %return
+    i32 1, label %sw.bb1
+  ]
+sw.bb1: br label %return
+sw.default: br label %return
+return:
+  %x = phi i32 [ 3, %sw.default ], [ 7, %sw.bb1 ], [ 9, %entry ]
+  ret i32 %x
+; CHECK-LABEL: @twocases(
+; CHECK: switch i32
+; CHECK-NOT: @switch.table
+}