stop unnecessarily passing around span argument for Miri function calls

Author: RalfJung

src/librustc_mir/const_eval/machine.rs

@@ -8,9 +8,9 @@ use std::hash::Hash;
 use rustc_data_structures::fx::FxHashMap;
 
 use rustc_ast::ast::Mutability;
+use rustc_hir::def_id::DefId;
 use rustc_middle::mir::AssertMessage;
 use rustc_span::symbol::Symbol;
-use rustc_span::{def_id::DefId, Span};
 
 use crate::interpret::{
     self, AllocId, Allocation, GlobalId, ImmTy, InterpCx, InterpResult, Memory, MemoryKind, OpTy,
@@ -64,7 +64,6 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter> {
     /// If this returns successfully (`Ok`), the function should just be evaluated normally.
     fn hook_panic_fn(
         &mut self,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx>],
     ) -> InterpResult<'tcx> {
@@ -77,7 +76,7 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter> {
 
             let msg_place = self.deref_operand(args[0])?;
             let msg = Symbol::intern(self.read_str(msg_place)?);
-            let span = self.find_closest_untracked_caller_location().unwrap_or(span);
+            let span = self.find_closest_untracked_caller_location();
             let (file, line, col) = self.location_triple_for_span(span);
             Err(ConstEvalErrKind::Panic { msg, file, line, col }.into())
         } else {
@@ -191,7 +190,6 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
 
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx>],
         ret: Option<(PlaceTy<'tcx>, mir::BasicBlock)>,
@@ -213,7 +211,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
             } else {
                 // Some functions we support even if they are non-const -- but avoid testing
                 // that for const fn!
-                ecx.hook_panic_fn(span, instance, args)?;
+                ecx.hook_panic_fn(instance, args)?;
                 // We certainly do *not* want to actually call the fn
                 // though, so be sure we return here.
                 throw_unsup_format!("calling non-const function `{}`", instance)
@@ -248,13 +246,12 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
 
     fn call_intrinsic(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx>],
         ret: Option<(PlaceTy<'tcx>, mir::BasicBlock)>,
         _unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx> {
-        if ecx.emulate_intrinsic(span, instance, args, ret)? {
+        if ecx.emulate_intrinsic(instance, args, ret)? {
             return Ok(());
         }
         // An intrinsic that we do not support

src/librustc_mir/interpret/intrinsics.rs

@@ -15,7 +15,6 @@ use rustc_middle::ty::layout::{LayoutOf, Primitive, Size};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::{sym, Symbol};
-use rustc_span::Span;
 
 use super::{ImmTy, InterpCx, Machine, OpTy, PlaceTy};
 
@@ -78,7 +77,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     /// Returns `true` if emulation happened.
     pub fn emulate_intrinsic(
         &mut self,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, M::PointerTag>],
         ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
@@ -101,7 +99,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // `src/librustc_middle/ty/constness.rs`
         match intrinsic_name {
             sym::caller_location => {
-                let span = self.find_closest_untracked_caller_location().unwrap_or(span);
+                let span = self.find_closest_untracked_caller_location();
                 let location = self.alloc_caller_location_for_span(span);
                 self.write_scalar(location.ptr, dest)?;
             }
@@ -118,7 +116,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     sym::needs_drop => self.tcx.types.bool,
                     sym::type_id => self.tcx.types.u64,
                     sym::type_name => self.tcx.mk_static_str(),
-                    _ => span_bug!(span, "Already checked for nullary intrinsics"),
+                    _ => bug!("already checked for nullary intrinsics"),
                 };
                 let val = self.const_eval(gid, ty)?;
                 self.copy_op(val, dest)?;

src/librustc_mir/interpret/intrinsics/caller_location.rs

@@ -14,16 +14,19 @@ impl<'mir, 'tcx, 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]`. If the first frame found lacks `#[track_caller]`, then
     /// `None` is returned and the callsite of the function invocation itself should be used.
-    crate fn find_closest_untracked_caller_location(&self) -> Option<Span> {
-        let mut caller_span = None;
-        for next_caller in self.stack.iter().rev() {
-            caller_span = next_caller.current_source_info().map(|si| si.span).or_else(|| caller_span);
-            if !next_caller.instance.def.requires_caller_location(*self.tcx) {
-                return caller_span;
-            }
-        }
-
-        caller_span
+    crate fn find_closest_untracked_caller_location(&self) -> Span {
+        self.stack
+            .iter()
+            .rev()
+            // Skip `#[track_caller]` frames.
+            .skip_while(|frame| frame.instance.def.requires_caller_location(*self.tcx))
+            // Find next frame with source info.
+            .find_map(|frame| frame.current_source_info())
+            .map(|si| si.span)
+            // Fallback to current frame. That one has to have source_info as only
+            // currently unwinding frames without cleanup do *not* have it -- and those
+            // frames do not call this intrinsic.
+            .unwrap_or_else(|| self.frame().current_source_info().unwrap().span)
     }
 
     /// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.

src/librustc_mir/interpret/machine.rs

@@ -7,7 +7,7 @@ use std::hash::Hash;
 
 use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty};
-use rustc_span::{def_id::DefId, Span};
+use rustc_span::def_id::DefId;
 
 use super::{
     AllocId, Allocation, AllocationExtra, Frame, ImmTy, InterpCx, InterpResult, Memory, MemoryKind,
@@ -135,7 +135,6 @@ pub trait Machine<'mir, 'tcx>: Sized {
     /// was used.
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Self::PointerTag>],
         ret: Option<(PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
@@ -156,7 +155,6 @@ pub trait Machine<'mir, 'tcx>: Sized {
     /// responsibility to advance the instruction pointer as appropriate.
     fn call_intrinsic(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Self::PointerTag>],
         ret: Option<(PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,

src/librustc_mir/interpret/terminator.rs

@@ -4,7 +4,6 @@ use std::convert::TryFrom;
 use rustc_middle::ty::layout::{self, LayoutOf, TyAndLayout};
 use rustc_middle::ty::Instance;
 use rustc_middle::{mir, ty};
-use rustc_span::source_map::Span;
 use rustc_target::spec::abi::Abi;
 
 use super::{
@@ -71,14 +70,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     Some((dest, ret)) => Some((self.eval_place(dest)?, *ret)),
                     None => None,
                 };
-                self.eval_fn_call(
-                    fn_val,
-                    terminator.source_info.span,
-                    abi,
-                    &args[..],
-                    ret,
-                    *cleanup,
-                )?;
+                self.eval_fn_call(fn_val, abi, &args[..], ret, *cleanup)?;
             }
 
             Drop { ref location, target, unwind } => {
@@ -88,7 +80,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 trace!("TerminatorKind::drop: {:?}, type {}", location, ty);
 
                 let instance = Instance::resolve_drop_in_place(*self.tcx, ty);
-                self.drop_in_place(place, instance, terminator.source_info.span, target, unwind)?;
+                self.drop_in_place(place, instance, target, unwind)?;
             }
 
             Assert { ref cond, expected, ref msg, target, cleanup } => {
@@ -196,7 +188,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     fn eval_fn_call(
         &mut self,
         fn_val: FnVal<'tcx, M::ExtraFnVal>,
-        span: Span,
         caller_abi: Abi,
         args: &[OpTy<'tcx, M::PointerTag>],
         ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
@@ -242,7 +233,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match instance.def {
             ty::InstanceDef::Intrinsic(..) => {
                 assert!(caller_abi == Abi::RustIntrinsic || caller_abi == Abi::PlatformIntrinsic);
-                M::call_intrinsic(self, span, instance, args, ret, unwind)
+                M::call_intrinsic(self, instance, args, ret, unwind)
             }
             ty::InstanceDef::VtableShim(..)
             | ty::InstanceDef::ReifyShim(..)
@@ -252,7 +243,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             | ty::InstanceDef::CloneShim(..)
             | ty::InstanceDef::Item(_) => {
                 // We need MIR for this fn
-                let body = match M::find_mir_or_eval_fn(self, span, instance, args, ret, unwind)? {
+                let body = match M::find_mir_or_eval_fn(self, instance, args, ret, unwind)? {
                     Some(body) => body,
                     None => return Ok(()),
                 };
@@ -406,7 +397,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     OpTy::from(ImmTy { layout: this_receiver_ptr, imm: receiver_place.ptr.into() });
                 trace!("Patched self operand to {:#?}", args[0]);
                 // recurse with concrete function
-                self.eval_fn_call(drop_fn, span, caller_abi, &args, ret, unwind)
+                self.eval_fn_call(drop_fn, caller_abi, &args, ret, unwind)
             }
         }
     }
@@ -415,7 +406,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         &mut self,
         place: PlaceTy<'tcx, M::PointerTag>,
         instance: ty::Instance<'tcx>,
-        span: Span,
         target: mir::BasicBlock,
         unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx> {
@@ -443,7 +433,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         self.eval_fn_call(
             FnVal::Instance(instance),
-            span,
             Abi::Rust,
             &[arg.into()],
             Some((dest.into(), target)),

src/librustc_mir/transform/const_prop.rs

@@ -183,7 +183,6 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
 
     fn find_mir_or_eval_fn(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _span: Span,
         _instance: ty::Instance<'tcx>,
         _args: &[OpTy<'tcx>],
         _ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
@@ -204,7 +203,6 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
 
     fn call_intrinsic(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _span: Span,
         _instance: ty::Instance<'tcx>,
         _args: &[OpTy<'tcx>],
         _ret: Option<(PlaceTy<'tcx>, BasicBlock)>,