Rollup merge of #141569 - workingjubilee:canonicalize-abi, r=bjorn3

Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`

Our `conv_from_spec_abi`, `adjust_abi`, and `is_abi_supported` combine to give us a very confusing way of reasoning about what _actual_ calling convention we want to lower our code to and whether we want to compile the resulting code at all. Instead of leaving this code as a miniature adventure game in which someone tries to combine stateful mutations into a Rube Goldberg machine that will let them escape the maze and arrive at the promised land of codegen, we let `AbiMap` devour this complexity. Once you have an `AbiMap`, you can answer which `ExternAbi`s will lower to what `CanonAbi`s (and whether they will lower at all).

Removed:
- `conv_from_spec_abi` replaced by `AbiMap::canonize_abi`
- `adjust_abi` replaced by same
- `Conv::PreserveAll` as unused
- `Conv::Cold` as unused
- `enum Conv` replaced by `enum CanonAbi`

target-spec.json changes:
- If you have a target-spec.json then now your "entry-abi" key will be specified in terms of one of the `"{abi}"` strings Rust recognizes, e.g.
```json
    "entry-abi": "C",
    "entry-abi": "win64",
    "entry-abi": "aapcs",
```

Author: matthiaskrgr

src/helpers.rs

@@ -3,7 +3,7 @@ use std::time::Duration;
 use std::{cmp, iter};
 
 use rand::RngCore;
-use rustc_abi::{Align, ExternAbi, FieldIdx, FieldsShape, Size, Variants};
+use rustc_abi::{Align, CanonAbi, ExternAbi, FieldIdx, FieldsShape, Size, Variants};
 use rustc_apfloat::Float;
 use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_hir::Safety;
@@ -18,7 +18,7 @@ use rustc_middle::ty::{self, Binder, FloatTy, FnSig, IntTy, Ty, TyCtxt, UintTy};
 use rustc_session::config::CrateType;
 use rustc_span::{Span, Symbol};
 use rustc_symbol_mangling::mangle_internal_symbol;
-use rustc_target::callconv::{Conv, FnAbi};
+use rustc_target::callconv::FnAbi;
 
 use crate::*;
 
@@ -936,11 +936,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn check_callconv<'a>(
         &self,
         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
-        exp_abi: Conv,
+        exp_abi: CanonAbi,
     ) -> InterpResult<'a, ()> {
         if fn_abi.conv != exp_abi {
             throw_ub_format!(
-                "calling a function with calling convention {exp_abi} using caller calling convention {}",
+                r#"calling a function with calling convention "{exp_abi}" using caller calling convention "{}""#,
                 fn_abi.conv
             );
         }
@@ -973,7 +973,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn check_abi_and_shim_symbol_clash(
         &mut self,
         abi: &FnAbi<'tcx, Ty<'tcx>>,
-        exp_abi: Conv,
+        exp_abi: CanonAbi,
         link_name: Symbol,
     ) -> InterpResult<'tcx, ()> {
         self.check_callconv(abi, exp_abi)?;
@@ -998,7 +998,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn check_shim<'a, const N: usize>(
         &mut self,
         abi: &FnAbi<'tcx, Ty<'tcx>>,
-        exp_abi: Conv,
+        exp_abi: CanonAbi,
         link_name: Symbol,
         args: &'a [OpTy<'tcx>],
     ) -> InterpResult<'tcx, &'a [OpTy<'tcx>; N]> {
@@ -1098,7 +1098,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn check_shim_variadic<'a, const N: usize>(
         &mut self,
         abi: &FnAbi<'tcx, Ty<'tcx>>,
-        exp_abi: Conv,
+        exp_abi: CanonAbi,
         link_name: Symbol,
         args: &'a [OpTy<'tcx>],
     ) -> InterpResult<'tcx, (&'a [OpTy<'tcx>; N], &'a [OpTy<'tcx>])>

src/shims/aarch64.rs

@@ -1,7 +1,8 @@
+use rustc_abi::CanonAbi;
 use rustc_middle::mir::BinOp;
 use rustc_middle::ty::Ty;
 use rustc_span::Symbol;
-use rustc_target::callconv::{Conv, FnAbi};
+use rustc_target::callconv::FnAbi;
 
 use crate::*;
 
@@ -19,7 +20,7 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let unprefixed_name = link_name.as_str().strip_prefix("llvm.aarch64.").unwrap();
         match unprefixed_name {
             "isb" => {
-                let [arg] = this.check_shim(abi, Conv::C, link_name, args)?;
+                let [arg] = this.check_shim(abi, CanonAbi::C, link_name, args)?;
                 let arg = this.read_scalar(arg)?.to_i32()?;
                 match arg {
                     // SY ("full system scope")
@@ -37,7 +38,7 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             // `left` input, the second half of the output from the `right` input.
             // https://developer.arm.com/architectures/instruction-sets/intrinsics/vpmaxq_u8
             "neon.umaxp.v16i8" => {
-                let [left, right] = this.check_shim(abi, Conv::C, link_name, args)?;
+                let [left, right] = this.check_shim(abi, CanonAbi::C, link_name, args)?;
 
                 let (left, left_len) = this.project_to_simd(left)?;
                 let (right, right_len) = this.project_to_simd(right)?;

src/shims/backtrace.rs

@@ -1,8 +1,8 @@
-use rustc_abi::Size;
+use rustc_abi::{CanonAbi, Size};
 use rustc_middle::ty::layout::LayoutOf as _;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_span::{BytePos, Loc, Symbol, hygiene};
-use rustc_target::callconv::{Conv, FnAbi};
+use rustc_target::callconv::FnAbi;
 
 use crate::*;
 
@@ -16,7 +16,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         dest: &MPlaceTy<'tcx>,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
-        let [flags] = this.check_shim(abi, Conv::Rust, link_name, args)?;
+        let [flags] = this.check_shim(abi, CanonAbi::Rust, link_name, args)?;
 
         let flags = this.read_scalar(flags)?.to_u64()?;
         if flags != 0 {
@@ -38,7 +38,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let ptr_ty = this.machine.layouts.mut_raw_ptr.ty;
         let ptr_layout = this.layout_of(ptr_ty)?;
 
-        let [flags, buf] = this.check_shim(abi, Conv::Rust, link_name, args)?;
+        let [flags, buf] = this.check_shim(abi, CanonAbi::Rust, link_name, args)?;
 
         let flags = this.read_scalar(flags)?.to_u64()?;
         let buf_place = this.deref_pointer_as(buf, ptr_layout)?;
@@ -118,7 +118,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         dest: &MPlaceTy<'tcx>,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
-        let [ptr, flags] = this.check_shim(abi, Conv::Rust, link_name, args)?;
+        let [ptr, flags] = this.check_shim(abi, CanonAbi::Rust, link_name, args)?;
 
         let flags = this.read_scalar(flags)?.to_u64()?;
 
@@ -190,7 +190,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let this = self.eval_context_mut();
 
         let [ptr, flags, name_ptr, filename_ptr] =
-            this.check_shim(abi, Conv::Rust, link_name, args)?;
+            this.check_shim(abi, CanonAbi::Rust, link_name, args)?;
 
         let flags = this.read_scalar(flags)?.to_u64()?;
         if flags != 0 {