interpret: call caller_location logic the same way codegen does, and share some code

Author: RalfJung

compiler/rustc_codegen_cranelift/src/common.rs

@@ -433,16 +433,7 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
     // Note: must be kept in sync with get_caller_location from cg_ssa
     pub(crate) fn get_caller_location(&mut self, mut source_info: mir::SourceInfo) -> CValue<'tcx> {
         let span_to_caller_location = |fx: &mut FunctionCx<'_, '_, 'tcx>, span: Span| {
-            use rustc_session::RemapFileNameExt;
-            let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
-            let caller = fx.tcx.sess.source_map().lookup_char_pos(topmost.lo());
-            let const_loc = fx.tcx.const_caller_location((
-                rustc_span::symbol::Symbol::intern(
-                    &caller.file.name.for_codegen(&fx.tcx.sess).to_string_lossy(),
-                ),
-                caller.line as u32,
-                caller.col_display as u32 + 1,
-            ));
+            let const_loc = fx.tcx.span_as_caller_location(span);
             crate::constant::codegen_const_value(fx, const_loc, fx.tcx.caller_location_ty())
         };
 

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1454,14 +1454,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let tcx = bx.tcx();
 
         let mut span_to_caller_location = |span: Span| {
-            use rustc_session::RemapFileNameExt;
-            let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
-            let caller = tcx.sess.source_map().lookup_char_pos(topmost.lo());
-            let const_loc = tcx.const_caller_location((
-                Symbol::intern(&caller.file.name.for_codegen(self.cx.sess()).to_string_lossy()),
-                caller.line as u32,
-                caller.col_display as u32 + 1,
-            ));
+            let const_loc = tcx.span_as_caller_location(span);
             OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
         };
 

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -90,7 +90,7 @@ fn eval_body_using_ecx<'mir, 'tcx>(
 /// that inform us about the generic bounds of the constant. E.g., using an associated constant
 /// of a function's generic parameter will require knowledge about the bounds on the generic
 /// parameter. These bounds are passed to `mk_eval_cx` via the `ParamEnv` argument.
-pub(super) fn mk_eval_cx<'mir, 'tcx>(
+pub(crate) fn mk_eval_cx<'mir, 'tcx>(
     tcx: TyCtxt<'tcx>,
     root_span: Span,
     param_env: ty::ParamEnv<'tcx>,

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -4,6 +4,7 @@ use rustc_middle::mir;
 use rustc_middle::mir::interpret::PointerArithmetic;
 use rustc_middle::ty::layout::{FnAbiOf, TyAndLayout};
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_span::Span;
 use std::borrow::Borrow;
 use std::hash::Hash;
 use std::ops::ControlFlow;
@@ -181,6 +182,24 @@ impl interpret::MayLeak for ! {
 }
 
 impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
+    fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
+        let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
+        let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
+
+        use rustc_session::{config::RemapPathScopeComponents, RemapFileNameExt};
+        (
+            Symbol::intern(
+                &caller
+                    .file
+                    .name
+                    .for_scope(&self.tcx.sess, RemapPathScopeComponents::DIAGNOSTICS)
+                    .to_string_lossy(),
+            ),
+            u32::try_from(caller.line).unwrap(),
+            u32::try_from(caller.col_display).unwrap().checked_add(1).unwrap(),
+        )
+    }
+
     /// "Intercept" a function call, because we have something special to do for it.
     /// All `#[rustc_do_not_const_check]` functions should be hooked here.
     /// If this returns `Some` function, which may be `instance` or a different function with

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -1,12 +1,12 @@
 // Not in interpret to make sure we do not use private implementation details
 
 use crate::errors::MaxNumNodesInConstErr;
-use crate::interpret::{intern_const_alloc_recursive, InternKind, InterpCx, Scalar};
+use crate::interpret::InterpCx;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
+use rustc_span::source_map::DUMMY_SP;
 
 mod error;
 mod eval_queries;
@@ -20,20 +20,6 @@ pub use fn_queries::*;
 pub use machine::*;
 pub(crate) use valtrees::{const_to_valtree_inner, valtree_to_const_value};
 
-pub(crate) fn const_caller_location(
-    tcx: TyCtxt<'_>,
-    (file, line, col): (Symbol, u32, u32),
-) -> mir::ConstValue<'_> {
-    trace!("const_caller_location: {}:{}:{}", file, line, col);
-    let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::reveal_all(), CanAccessStatics::No);
-
-    let loc_place = ecx.alloc_caller_location(file, line, col);
-    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))
-}
-
 // We forbid type-level constants that contain more than `VALTREE_MAX_NODES` nodes.
 const VALTREE_MAX_NODES: usize = 100000;
 

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -595,6 +595,68 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
+    /// Walks up the callstack from the intrinsic's callsite, searching for the first callsite in a
+    /// frame which is not `#[track_caller]`. This is the fancy version of `cur_span`.
+    pub(crate) fn find_closest_untracked_caller_location(&self) -> Span {
+        for frame in self.stack().iter().rev() {
+            debug!("find_closest_untracked_caller_location: checking frame {:?}", frame.instance);
+
+            // Assert that the frame we look at is actually executing code currently
+            // (`loc` is `Right` when we are unwinding and the frame does not require cleanup).
+            let loc = frame.loc.left().unwrap();
+
+            // This could be a non-`Call` terminator (such as `Drop`), or not a terminator at all
+            // (such as `box`). Use the normal span by default.
+            let mut source_info = *frame.body.source_info(loc);
+
+            // If this is a `Call` terminator, use the `fn_span` instead.
+            let block = &frame.body.basic_blocks[loc.block];
+            if loc.statement_index == block.statements.len() {
+                debug!(
+                    "find_closest_untracked_caller_location: got terminator {:?} ({:?})",
+                    block.terminator(),
+                    block.terminator().kind,
+                );
+                if let mir::TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
+                    source_info.span = fn_span;
+                }
+            }
+
+            // Note: this must be kept in sync with get_caller_location from cg_ssa.
+
+            // Walk up the `SourceScope`s, in case some of them are from MIR inlining.
+            // If so, the starting `source_info.span` is in the innermost inlined
+            // function, and will be replaced with outer callsite spans as long
+            // as the inlined functions were `#[track_caller]`.
+            loop {
+                let scope_data = &frame.body.source_scopes[source_info.scope];
+
+                if let Some((callee, callsite_span)) = scope_data.inlined {
+                    // Stop inside the most nested non-`#[track_caller]` function,
+                    // before ever reaching its caller (which is irrelevant).
+                    if !callee.def.requires_caller_location(*self.tcx) {
+                        return source_info.span;
+                    }
+                    source_info.span = callsite_span;
+                }
+
+                // Skip past all of the parents with `inlined: None`.
+                match scope_data.inlined_parent_scope {
+                    Some(parent) => source_info.scope = parent,
+                    None => break,
+                }
+            }
+
+            // Stop inside the most nested non-`#[track_caller]` function,
+            // before ever reaching its caller (which is irrelevant).
+            if !frame.instance.def.requires_caller_location(*self.tcx) {
+                return source_info.span;
+            }
+        }
+
+        span_bug!(self.cur_span(), "no non-`#[track_caller]` frame found")
+    }
+
     #[inline(always)]
     pub fn layout_of_local(
         &self,

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -22,8 +22,6 @@ use super::{
 
 use crate::fluent_generated as fluent;
 
-mod caller_location;
-
 fn numeric_intrinsic<Prov>(name: Symbol, bits: u128, kind: Primitive) -> Scalar<Prov> {
     let size = match kind {
         Primitive::Int(integer, _) => integer.size(),
@@ -130,8 +128,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match intrinsic_name {
             sym::caller_location => {
                 let span = self.find_closest_untracked_caller_location();
-                let location = self.alloc_caller_location_for_span(span);
-                self.write_immediate(location.to_ref(self), dest)?;
+                let val = self.tcx.span_as_caller_location(span);
+                let val =
+                    self.const_val_to_op(val, self.tcx.caller_location_ty(), Some(dest.layout))?;
+                self.copy_op(&val, dest, /* allow_transmute */ false)?;
             }
 
             sym::min_align_of_val | sym::size_of_val => {

compiler/rustc_const_eval/src/interpret/intrinsics/caller_location.rs

@@ -49,7 +49,7 @@ pub fn provide(providers: &mut Providers) {
     const_eval::provide(providers);
     providers.eval_to_const_value_raw = const_eval::eval_to_const_value_raw_provider;
     providers.eval_to_allocation_raw = const_eval::eval_to_allocation_raw_provider;
-    providers.const_caller_location = const_eval::const_caller_location;
+    providers.const_caller_location = util::caller_location::const_caller_location_provider;
     providers.eval_to_valtree = |tcx, param_env_and_value| {
         let (param_env, raw) = param_env_and_value.into_parts();
         const_eval::eval_to_valtree(tcx, param_env, raw)