Auto merge of #129658 - saethlin:spare-a-crumb, r=<try>

Add some track_caller info to precondition panics

r? `@ghost`

Thought of this while looking at #129642 (comment)

Author: bors

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -790,13 +790,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let (fn_abi, llfn, instance) =
                     common::build_langcall(bx, Some(source_info.span), LangItem::PanicNounwind);
 
+                let location = self.get_caller_location(bx, source_info).immediate();
+
                 // Codegen the actual panic invoke/call.
                 helper.do_call(
                     self,
                     bx,
                     fn_abi,
                     llfn,
-                    &[msg.0, msg.1],
+                    &[msg.0, msg.1, location],
                     target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)),
                     unwind,
                     &[],

compiler/rustc_codegen_ssa/src/size_of_val.rs

@@ -74,12 +74,20 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             // duplicated plenty of times.)
             let fn_ty = bx.fn_decl_backend_type(fn_abi);
 
+            let const_loc = bx.tcx().span_as_caller_location(rustc_span::DUMMY_SP);
+            let location = crate::mir::operand::OperandRef::from_const(
+                bx,
+                const_loc,
+                bx.tcx().caller_location_ty(),
+            )
+            .immediate();
+
             bx.call(
                 fn_ty,
                 /* fn_attrs */ None,
                 Some(fn_abi),
                 llfn,
-                &[msg.0, msg.1],
+                &[msg.0, msg.1, location],
                 None,
                 None,
             );

compiler/rustc_const_eval/src/util/caller_location.rs

@@ -1,3 +1,5 @@
+use std::collections::hash_map::Entry;
+
 use rustc_hir::LangItem;
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::layout::LayoutOf;
@@ -57,6 +59,11 @@ pub(crate) fn const_caller_location_provider(
     col: u32,
 ) -> mir::ConstValue<'_> {
     trace!("const_caller_location: {}:{}:{}", file, line, col);
+    let mut cache = tcx.caller_location_cache.lock();
+    let entry = match cache.entry((file, line, col)) {
+        Entry::Occupied(oe) => return *oe.get(),
+        Entry::Vacant(ve) => ve,
+    };
     let mut ecx = mk_eval_cx_to_read_const_val(
         tcx.tcx,
         tcx.span,
@@ -68,5 +75,7 @@ pub(crate) fn const_caller_location_provider(
     if intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &loc_place).is_err() {
         bug!("intern_const_alloc_recursive should not error in this case")
     }
-    mir::ConstValue::Scalar(Scalar::from_maybe_pointer(loc_place.ptr(), &tcx))
+    let val = mir::ConstValue::Scalar(Scalar::from_maybe_pointer(loc_place.ptr(), &tcx));
+    entry.insert(val);
+    val
 }

compiler/rustc_middle/src/ty/context.rs

@@ -66,7 +66,7 @@ use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::{resolve_bound_vars, stability};
 use crate::mir::interpret::{self, Allocation, ConstAllocation};
-use crate::mir::{Body, Local, Place, PlaceElem, ProjectionKind, Promoted};
+use crate::mir::{Body, ConstValue, Local, Place, PlaceElem, ProjectionKind, Promoted};
 use crate::query::plumbing::QuerySystem;
 use crate::query::{IntoQueryParam, LocalCrate, Providers, TyCtxtAt};
 use crate::thir::Thir;
@@ -1297,6 +1297,8 @@ pub struct GlobalCtxt<'tcx> {
     /// Stores memory for globals (statics/consts).
     pub(crate) alloc_map: Lock<interpret::AllocMap<'tcx>>,
 
+    pub caller_location_cache: Lock<FxHashMap<(Symbol, u32, u32), ConstValue<'tcx>>>,
+
     current_gcx: CurrentGcx,
 }
 
@@ -1527,6 +1529,7 @@ impl<'tcx> TyCtxt<'tcx> {
             canonical_param_env_cache: Default::default(),
             data_layout,
             alloc_map: Lock::new(interpret::AllocMap::new()),
+            caller_location_cache: Default::default(),
             current_gcx,
         }
     }

library/core/src/alloc/layout.rs

@@ -128,6 +128,7 @@ impl Layout {
     #[must_use]
     #[inline]
     #[rustc_allow_const_fn_unstable(ptr_alignment_type)]
+    #[track_caller]
     pub const unsafe fn from_size_align_unchecked(size: usize, align: usize) -> Self {
         assert_unsafe_precondition!(
             check_library_ub,

library/core/src/ascii/ascii_char.rs

@@ -503,6 +503,7 @@ impl AsciiChar {
     /// something useful. It might be tightened before stabilization.)
     #[unstable(feature = "ascii_char", issue = "110998")]
     #[inline]
+    #[track_caller]
     pub const unsafe fn digit_unchecked(d: u8) -> Self {
         assert_unsafe_precondition!(
             check_language_ub,

library/core/src/char/convert.rs

@@ -21,6 +21,7 @@ pub(super) const fn from_u32(i: u32) -> Option<char> {
 /// Converts a `u32` to a `char`, ignoring validity. See [`char::from_u32_unchecked`].
 #[inline]
 #[must_use]
+#[track_caller]
 pub(super) const unsafe fn from_u32_unchecked(i: u32) -> char {
     // SAFETY: the caller must guarantee that `i` is a valid char value.
     unsafe {

library/core/src/hint.rs

@@ -97,7 +97,7 @@ use crate::{intrinsics, ub_checks};
 #[inline]
 #[stable(feature = "unreachable", since = "1.27.0")]
 #[rustc_const_stable(feature = "const_unreachable_unchecked", since = "1.57.0")]
-#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+#[track_caller]
 pub const unsafe fn unreachable_unchecked() -> ! {
     ub_checks::assert_unsafe_precondition!(
         check_language_ub,

library/core/src/intrinsics.rs

@@ -3288,7 +3288,7 @@ pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(_ptr: *cons
 #[rustc_allowed_through_unstable_modules]
 #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
 #[inline(always)]
-#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+#[track_caller]
 #[rustc_diagnostic_item = "ptr_copy_nonoverlapping"]
 pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
@@ -3390,7 +3390,7 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
 #[rustc_allowed_through_unstable_modules]
 #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
 #[inline(always)]
-#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+#[track_caller]
 #[rustc_diagnostic_item = "ptr_copy"]
 pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
@@ -3470,7 +3470,7 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
 #[rustc_allowed_through_unstable_modules]
 #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
 #[inline(always)]
-#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+#[track_caller]
 #[rustc_diagnostic_item = "ptr_write_bytes"]
 pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     extern "rust-intrinsic" {

library/core/src/num/int_macros.rs

@@ -510,7 +510,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,
@@ -662,7 +662,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,
@@ -814,7 +814,7 @@ macro_rules! int_impl {
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,
@@ -1163,7 +1163,7 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[rustc_const_unstable(feature = "unchecked_neg", issue = "85122")]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_neg(self) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,
@@ -1296,7 +1296,7 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[rustc_const_unstable(feature = "unchecked_shifts", issue = "85122")]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,
@@ -1422,7 +1422,7 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[rustc_const_unstable(feature = "unchecked_shifts", issue = "85122")]
         #[inline(always)]
-        #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+        #[track_caller]
         pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
             assert_unsafe_precondition!(
                 check_language_ub,