add CTFE stress test

Author: RalfJung

collector/benchmarks/ctfe-stress/Cargo.lock

@@ -0,0 +1,4 @@
+[package]
+name = "ctfe-stress"
+version = "0.1.0"
+authors = ["Ralf Jung <[email protected]>"]

collector/benchmarks/ctfe-stress/Cargo.toml

@@ -0,0 +1,57 @@
+#![feature(const_fn, const_let)]
+#![allow(unused_must_use)]
+
+// Try to make CTFE actually do a lot of computation, without producing a big result.
+// And without support for loops.
+
+macro_rules! const_repeat {
+    // Base case: Use 16 at the end to avoid function calls at the leaves as much as possibele.
+    ([16] $e: expr, $T: ty) => {{
+        $e; $e; $e; $e;
+        $e; $e; $e; $e;
+        $e; $e; $e; $e;
+        $e; $e; $e; $e
+    }};
+    ([1] $e: expr, $T: ty) => {{
+        $e
+    }};
+    // Recursive case: Take a 16
+    ([16 $($n: tt)*] $e: expr, $T: ty) => {{
+        const fn e() -> $T { const_repeat!([$($n)*] $e, $T) }
+        e(); e(); e(); e();
+        e(); e(); e(); e();
+        e(); e(); e(); e();
+        e(); e(); e(); e()
+    }};
+    // Recursive case: Take a 4
+    ([4 $($n: tt)*] $e: expr, $T: ty) => {{
+        const fn e() -> $T { const_repeat!([$($n)*] $e, $T) }
+        e(); e(); e(); e()
+    }};
+    // Recursive case: Take a 2
+    ([2 $($n: tt)*] $e: expr, $T: ty) => {{
+        const fn e() -> $T { const_repeat!([$($n)*] $e, $T) }
+        e(); e()
+    }};
+    //
+    ($e: expr, $T: ty) => (const_repeat!([16 16 16 16 16] $e, $T));
+}
+macro_rules! expensive_static {
+    ($name: ident : $T: ty = $e : expr) =>
+        (pub static $name : $T = const_repeat!($e, $T);)
+}
+
+pub trait Trait: Sync {}
+impl Trait for u32 {}
+const fn nop<T>(t: T) -> T { t }
+const fn inc(i: i32) -> i32 { i + 1 }
+
+expensive_static!(RELOCATIONS : &'static str = "hello");
+expensive_static!(FIELDS: &'static i32 = &("bar", 42, "foo", 3.14).1);
+expensive_static!(CHECKED_INDEX: u8 = b"foomp"[3]);
+expensive_static!(UNSIZING: &'static [u8] = b"foo");
+expensive_static!(UNSIZE_TRAIT: &'static Trait = &42u32);
+expensive_static!(CHAIN: usize = 42i32 as u8 as u64 as i8 as isize as usize);
+expensive_static!(OPS: i32 = ((((10 >> 1) + 3) * 7) / 2 - 12) << 4);
+expensive_static!(FORCE_ALLOC: i32 = *****(&&&&&5));
+expensive_static!(CONST_FN_SIMPLE: i32 = inc(42));