PNaCl: Implement computed gotos (indirectbr) by expanding out to switches

test/Transforms/NaCl/expand-indirectbr.ll

+; RUN: opt %s -expand-indirectbr -S | FileCheck %s
+
+
+@addresses = global [2 x i8*]
+    [i8* blockaddress(@indirectbr_example, %label1),
+     i8* blockaddress(@indirectbr_example, %label2)]
+; CHECK: @addresses = global [2 x i8*] [i8* inttoptr (i32 1 to i8*), i8* inttoptr (i32 2 to i8*)]
+
+
+define i32 @indirectbr_example(i8* %addr) {
+  indirectbr i8* %addr, [label %label1, label %label2]
+label1:
+  ret i32 100
+label2:
+  ret i32 200
+}
+; CHECK: define i32 @indirectbr_example
+; CHECK-NEXT: %indirectbr_cast = ptrtoint i8* %addr to i32
+; CHECK-NEXT: switch i32 %indirectbr_cast, label %indirectbr_default [
+; CHECK-NEXT:   i32 1, label %label1
+; CHECK-NEXT:   i32 2, label %label2
+; CHECK-NEXT: ]
+; CHECK: indirectbr_default:
+; CHECK-NEXT: unreachable
+
+
+define i32 @label_appears_twice(i8* %addr) {
+entry:
+  indirectbr i8* %addr, [label %label, label %label]
+label:
+  %val = phi i32 [ 123, %entry ], [ 123, %entry ]
+  ret i32 %val
+}
+; CHECK: define i32 @label_appears_twice
+; CHECK: switch i32 %indirectbr_cast, label %indirectbr_default [
+; CHECK-NEXT:   i32 1, label %label
+; CHECK-NEXT: ]
+; CHECK: %val = phi i32 [ 123, %entry ]
+
+
+define i8* @unused_blockaddress() {
+  ret i8* blockaddress (@unused_blockaddress, %dead_label)
+dead_label:
+  ret i8* null
+}
+; CHECK: define i8* @unused_blockaddress
+; CHECK-NEXT: ret i8* inttoptr (i32 -1 to i8*)
+
+
+; Check that the label is given a consistent switch value across all
+; indirectbr expansions.
+define i32 @multiple_indirectbr(i8* %addr) {
+  indirectbr i8* %addr, [label %label]
+  indirectbr i8* %addr, [label %label]
+label:
+  ret i32 100
+}
+; CHECK: define i32 @multiple_indirectbr
+; CHECK: switch i32 %indirectbr_cast{{[0-9]*}}, label %indirectbr_default [
+; CHECK-NEXT: i32 1, label %label
+; CHECK: switch i32 %indirectbr_cast{{[0-9]*}}, label %indirectbr_default [
+; CHECK-NEXT: i32 1, label %label