Auto merge of #113569 - RalfJung:miri, r=oli-obk

miri: protect Move() function arguments during the call

This gives `Move` operands a meaning specific to function calls:
- for the duration of the call, the place the operand comes from is protected, making all read and write accesses insta-UB.
- the contents of that place are reset to `Uninit`, so looking at them again after the function returns, we cannot observe their contents

Turns out we can replace the existing "retag return place" hack with the exact same sort of protection on the return place, which is nicely symmetric.

Fixes https://github.com/rust-lang/rust/issues/112564
Fixes https://github.com/rust-lang/miri/issues/2927

This starts with a Miri rustc-push, since we'd otherwise conflict with a PR that recently landed in Miri.
(The "miri tree borrows" commit is an unrelated cleanup I noticed while doing the PR. I can remove it if you prefer.)
r? `@oli-obk`

1 files changed, 7 insertions, 5 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index f9f645af41f..a20f0276b3e 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -22,7 +22,7 @@ use rustc_target::spec::abi::Abi as CallAbi;
 
 use crate::errors::{LongRunning, LongRunningWarn};
 use crate::interpret::{
-    self, compile_time_machine, AllocId, ConstAllocation, FnVal, Frame, ImmTy, InterpCx,
+    self, compile_time_machine, AllocId, ConstAllocation, FnArg, FnVal, Frame, ImmTy, InterpCx,
     InterpResult, OpTy, PlaceTy, Pointer, Scalar,
 };
 use crate::{errors, fluent_generated as fluent};
@@ -201,7 +201,7 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
     fn hook_special_const_fn(
         &mut self,
         instance: ty::Instance<'tcx>,
-        args: &[OpTy<'tcx>],
+        args: &[FnArg<'tcx>],
         dest: &PlaceTy<'tcx>,
         ret: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
@@ -210,6 +210,7 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
         if Some(def_id) == self.tcx.lang_items().panic_display()
             || Some(def_id) == self.tcx.lang_items().begin_panic_fn()
         {
+            let args = self.copy_fn_args(args)?;
             // &str or &&str
             assert!(args.len() == 1);
 
@@ -236,8 +237,9 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
 
             return Ok(Some(new_instance));
         } else if Some(def_id) == self.tcx.lang_items().align_offset_fn() {
+            let args = self.copy_fn_args(args)?;
             // For align_offset, we replace the function call if the pointer has no address.
-            match self.align_offset(instance, args, dest, ret)? {
+            match self.align_offset(instance, &args, dest, ret)? {
                 ControlFlow::Continue(()) => return Ok(Some(instance)),
                 ControlFlow::Break(()) => return Ok(None),
             }
@@ -293,7 +295,7 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
                     self.eval_fn_call(
                         FnVal::Instance(instance),
                         (CallAbi::Rust, fn_abi),
-                        &[addr, align],
+                        &[FnArg::Copy(addr), FnArg::Copy(align)],
                         /* with_caller_location = */ false,
                         dest,
                         ret,
@@ -427,7 +429,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         instance: ty::Instance<'tcx>,
         _abi: CallAbi,
-        args: &[OpTy<'tcx>],
+        args: &[FnArg<'tcx>],
         dest: &PlaceTy<'tcx>,
         ret: Option<mir::BasicBlock>,
         _unwind: mir::UnwindAction, // unwinding is not supported in consts