Auto merge of #82936 - oli-obk:valtree, r=RalfJung,lcnr,matthewjasper

Implement (but don't use) valtree and refactor in preparation of use

This PR does not cause any functional change. It refactors various things that are needed to make valtrees possible. This refactoring got big enough that I decided I'd want it reviewed as a PR instead of trying to make one huge PR with all the changes.

cc `@rust-lang/wg-const-eval` on the following commits:

* 2027184 implement valtree
* eeecea9 fallible Scalar -> ScalarInt
* 042f663 ScalarInt convenience methods

cc `@eddyb` on ef04a6d

cc `@rust-lang/wg-mir-opt` for cf1700c (`mir::Constant` can now represent either a `ConstValue` or a `ty::Const`, and it is totally possible to have two different representations for the same value)

4 files changed, 13 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/analyze.rs b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
index 31d5c87182d..38e928145a8 100644
--- a/compiler/rustc_codegen_ssa/src/mir/analyze.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
@@ -231,7 +231,7 @@ impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> Visitor<'tcx>
     fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Location) {
         let check = match terminator.kind {
             mir::TerminatorKind::Call { func: mir::Operand::Constant(ref c), ref args, .. } => {
-                match *c.literal.ty.kind() {
+                match *c.ty().kind() {
                     ty::FnDef(did, _) => Some((did, args)),
                     _ => None,
                 }
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index a8dda100763..04225ddd36f 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -635,12 +635,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         if i == 2 && intrinsic.as_str().starts_with("simd_shuffle") {
                             if let mir::Operand::Constant(constant) = arg {
                                 let c = self.eval_mir_constant(constant);
-                                let (llval, ty) = self.simd_shuffle_indices(
-                                    &bx,
-                                    constant.span,
-                                    constant.literal.ty,
-                                    c,
-                                );
+                                let (llval, ty) =
+                                    self.simd_shuffle_indices(&bx, constant.span, constant.ty(), c);
                                 return OperandRef {
                                     val: Immediate(llval),
                                     layout: bx.layout_of(ty),
@@ -830,7 +826,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         let const_value = self
                             .eval_mir_constant(constant)
                             .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved"));
-                        let ty = constant.literal.ty;
+                        let ty = constant.ty();
                         let size = bx.layout_of(ty).size;
                         let scalar = match const_value {
                             ConstValue::Scalar(s) => s,
@@ -864,7 +860,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
                 mir::InlineAsmOperand::SymFn { ref value } => {
                     let literal = self.monomorphize(value.literal);
-                    if let ty::FnDef(def_id, substs) = *literal.ty.kind() {
+                    if let ty::FnDef(def_id, substs) = *literal.ty().kind() {
                         let instance = ty::Instance::resolve_for_fn_ptr(
                             bx.tcx(),
                             ty::ParamEnv::reveal_all(),
diff --git a/compiler/rustc_codegen_ssa/src/mir/constant.rs b/compiler/rustc_codegen_ssa/src/mir/constant.rs
index b79a221a0e7..aa41acc3578 100644
--- a/compiler/rustc_codegen_ssa/src/mir/constant.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/constant.rs
@@ -16,7 +16,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         constant: &mir::Constant<'tcx>,
     ) -> Result<OperandRef<'tcx, Bx::Value>, ErrorHandled> {
         let val = self.eval_mir_constant(constant)?;
-        let ty = self.monomorphize(constant.literal.ty);
+        let ty = self.monomorphize(constant.ty());
         Ok(OperandRef::from_const(bx, val, ty))
     }
 
@@ -24,7 +24,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         &self,
         constant: &mir::Constant<'tcx>,
     ) -> Result<ConstValue<'tcx>, ErrorHandled> {
-        match self.monomorphize(constant.literal).val {
+        let ct = self.monomorphize(constant.literal);
+        let ct = match ct {
+            mir::ConstantKind::Ty(ct) => ct,
+            mir::ConstantKind::Val(val, _) => return Ok(val),
+        };
+        match ct.val {
             ty::ConstKind::Unevaluated(def, substs, promoted) => self
                 .cx
                 .tcx()
diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
index ea59e183118..a3f20abc82d 100644
--- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
@@ -372,7 +372,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         (var_ty, var_kind)
                     }
                     mir::VarDebugInfoContents::Const(c) => {
-                        let ty = self.monomorphize(c.literal.ty);
+                        let ty = self.monomorphize(c.ty());
                         (ty, VariableKind::LocalVariable)
                     }
                 };