Add passes for applying SFI sandboxing at the LLVM IR level

test/Transforms/NaCl/sandbox-indirect-calls.ll

+; RUN: opt < %s -sandbox-indirect-calls -S | FileCheck %s
+
+@addr_taker_var1 = global i32 ptrtoint (void ()* @target_func1 to i32)
+@addr_taker_var2 = global i32 ptrtoint (i32 (i32)* @target_func2 to i32)
+
+; CHECK: @addr_taker_var1 = global i32 1
+; CHECK: @addr_taker_var2 = global i32 2
+
+; CHECK: @__sfi_function_table = internal constant [3 x i8*] [i8* null, i8* bitcast (void ()* @target_func1 to i8*), i8* bitcast (i32 (i32)* @target_func2 to i8*)]
+
+
+define void @target_func1() {
+  ret void
+}
+
+define i32 @target_func2(i32 %arg) {
+  ret i32 %arg
+}
+
+; Direct calls should be left alone.
+define void @direct_call() {
+  call void @target_func1()
+  call i32 @target_func2(i32 123)
+  ret void
+}
+; CHECK: define void @direct_call() {
+; CHECK: call void @target_func1()
+; CHECK: call i32 @target_func2(i32 123)
+
+define i32 @addr_taker_func() {
+  %func = ptrtoint void ()* @target_func1 to i32
+  ret i32 %func
+}
+; CHECK: define i32 @addr_taker_func()
+; CHECK-NEXT: ret i32 1
+
+define void @caller(i32 %func) {
+  %func2 = inttoptr i32 %func to void ()*
+  call void %func2()
+  ret void
+}
+; CHECK: define void @caller(i32 %func) {
+; CHECK-NEXT: %func_gep = getelementptr {{.*}} @__sfi_function_table, i32 0, i32 %func
+; CHECK-NEXT: %func1 = load i8** %func_gep
+; CHECK-NEXT: %func_bc = bitcast i8* %func1 to void ()*
+; CHECK-NEXT: call void %func_bc()
+
+
+; Example of a function which doesn't follow the normal form, and
+; which isn't handled.
+;
+; declare void @f(...)
+;
+; define void @use_as_arg() {
+;   call void (...)* @f(void ()* @target_func)
+;   ret void
+; }