Rollup merge of #136580 - bjorn3:miri_fixes, r=lqd

Couple of changes to run rustc in miri

This is not the full set of patches required to run rustc in miri, but it is the fast majority of the changes to rustc itself. There is also a change to the jobserver crate necessary and on arm64 a change to the memchr crate. Running rustc in miri has already found some UB: https://github.com/rust-lang/rust/pull/136579

cc https://github.com/rust-lang/rust/issues/135870#issuecomment-2612470540

2 files changed, 20 insertions, 8 deletions

diff --git a/compiler/rustc_data_structures/src/memmap.rs b/compiler/rustc_data_structures/src/memmap.rs
index c7f66b2fee8..d64a5862f4e 100644
--- a/compiler/rustc_data_structures/src/memmap.rs
+++ b/compiler/rustc_data_structures/src/memmap.rs
@@ -3,13 +3,13 @@ use std::io;
 use std::ops::{Deref, DerefMut};
 
 /// A trivial wrapper for [`memmap2::Mmap`] (or `Vec<u8>` on WASM).
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(not(any(miri, target_arch = "wasm32")))]
 pub struct Mmap(memmap2::Mmap);
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(any(miri, target_arch = "wasm32"))]
 pub struct Mmap(Vec<u8>);
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(not(any(miri, target_arch = "wasm32")))]
 impl Mmap {
     /// # Safety
     ///
@@ -29,7 +29,7 @@ impl Mmap {
     }
 }
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(any(miri, target_arch = "wasm32"))]
 impl Mmap {
     #[inline]
     pub unsafe fn map(mut file: File) -> io::Result<Self> {
@@ -56,13 +56,13 @@ impl AsRef<[u8]> for Mmap {
     }
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(not(any(miri, target_arch = "wasm32")))]
 pub struct MmapMut(memmap2::MmapMut);
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(any(miri, target_arch = "wasm32"))]
 pub struct MmapMut(Vec<u8>);
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(not(any(miri, target_arch = "wasm32")))]
 impl MmapMut {
     #[inline]
     pub fn map_anon(len: usize) -> io::Result<Self> {
@@ -82,7 +82,7 @@ impl MmapMut {
     }
 }
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(any(miri, target_arch = "wasm32"))]
 impl MmapMut {
     #[inline]
     pub fn map_anon(len: usize) -> io::Result<Self> {
diff --git a/compiler/rustc_data_structures/src/stack.rs b/compiler/rustc_data_structures/src/stack.rs
index 3d6d0003483..102b3640911 100644
--- a/compiler/rustc_data_structures/src/stack.rs
+++ b/compiler/rustc_data_structures/src/stack.rs
@@ -17,6 +17,18 @@ const STACK_PER_RECURSION: usize = 16 * 1024 * 1024; // 16MB
 ///
 /// Should not be sprinkled around carelessly, as it causes a little bit of overhead.
 #[inline]
+#[cfg(not(miri))]
 pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
     stacker::maybe_grow(RED_ZONE, STACK_PER_RECURSION, f)
 }
+
+/// Grows the stack on demand to prevent stack overflow. Call this in strategic locations
+/// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit
+/// from this.
+///
+/// Should not be sprinkled around carelessly, as it causes a little bit of overhead.
+#[cfg(miri)]
+#[inline]
+pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
+    f()
+}