From a4be90ed16f57a1b0e9641642a8c7b5f39d0a827 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Tue, 19 Dec 2023 12:46:39 +0000
Subject: [PATCH] Merge commit '3a9bf729322fb5035518f99b9d76a742bf7c124e' into
 sync_cg_clif-2023-12-19

---
 build_system/tests.rs                         |   7 ++
 example/mini_core_hello_world.rs              |  11 --
 ...nable-the-exposed_provenance-feature.patch |  22 ++++
 patches/stdlib-lock.toml                      |  55 +++++----
 rust-toolchain                                |   2 +-
 scripts/test_rustc_tests.sh                   |   1 +
 src/base.rs                                   |  16 +--
 src/common.rs                                 |  14 ++-
 src/intrinsics/mod.rs                         |  20 ++--
 src/unsize.rs                                 | 110 +++++++++++++-----
 src/value_and_place.rs                        |  59 +++++-----
 y.cmd                                         |   9 ++
 y.ps1                                         |  12 ++
 13 files changed, 223 insertions(+), 115 deletions(-)
 create mode 100644 patches/0001-portable-simd-Enable-the-exposed_provenance-feature.patch
 create mode 100644 y.cmd
 create mode 100644 y.ps1

diff --git a/build_system/tests.rs b/build_system/tests.rs
index 1a38d5967f4..cb7b2454cd5 100644
--- a/build_system/tests.rs
+++ b/build_system/tests.rs
@@ -232,6 +232,13 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str)
         if runner.is_native {
             let mut test_cmd = PORTABLE_SIMD.test(&runner.target_compiler, &runner.dirs);
             test_cmd.arg("-q");
+            // FIXME remove after portable-simd update
+            test_cmd
+                .arg("--")
+                .arg("--skip")
+                .arg("core_simd::swizzle::simd_swizzle")
+                .arg("--skip")
+                .arg("core_simd::vector::Simd<T,N>::lanes");
             spawn_and_wait(test_cmd);
         }
     }),
diff --git a/example/mini_core_hello_world.rs b/example/mini_core_hello_world.rs
index afc51a47f14..1d51b499c8b 100644
--- a/example/mini_core_hello_world.rs
+++ b/example/mini_core_hello_world.rs
@@ -337,17 +337,6 @@ struct ExternTypeWrapper {
     static REF2: &u8 = REF1;
     assert_eq!(*REF1, *REF2);
 
-    extern "C" {
-        type A;
-    }
-
-    fn main() {
-        let x: &A = unsafe { &*(1usize as *const A) };
-
-        assert_eq!(unsafe { intrinsics::size_of_val(x) }, 0);
-        assert_eq!(unsafe { intrinsics::min_align_of_val(x) }, 1);
-    }
-
     #[repr(simd)]
     struct V([f64; 2]);
 
diff --git a/patches/0001-portable-simd-Enable-the-exposed_provenance-feature.patch b/patches/0001-portable-simd-Enable-the-exposed_provenance-feature.patch
new file mode 100644
index 00000000000..b8c0783f524
--- /dev/null
+++ b/patches/0001-portable-simd-Enable-the-exposed_provenance-feature.patch
@@ -0,0 +1,22 @@
+From a101a43b795431ce617e7782afb451f4853afc00 Mon Sep 17 00:00:00 2001
+From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
+Date: Thu, 7 Dec 2023 14:51:35 +0000
+Subject: [PATCH] Enable the exposed_provenance feature
+
+---
+ crates/core_simd/tests/pointers.rs | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/crates/core_simd/tests/pointers.rs b/crates/core_simd/tests/pointers.rs
+index 0ae8f83..06620d6 100644
+--- a/crates/core_simd/tests/pointers.rs
++++ b/crates/core_simd/tests/pointers.rs
+@@ -1,4 +1,4 @@
+-#![feature(portable_simd, strict_provenance)]
++#![feature(exposed_provenance, portable_simd, strict_provenance)]
+ 
+ use core_simd::simd::{Simd, SimdConstPtr, SimdMutPtr};
+ 
+-- 
+2.34.1
+
diff --git a/patches/stdlib-lock.toml b/patches/stdlib-lock.toml
index 8a690bada0d..8e213f71c3f 100644
--- a/patches/stdlib-lock.toml
+++ b/patches/stdlib-lock.toml
@@ -36,15 +36,18 @@ dependencies = [
 
 [[package]]
 name = "allocator-api2"
-version = "0.2.15"
+version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "56fc6cf8dc8c4158eed8649f9b8b0ea1518eb62b544fe9490d66fa0b349eafe9"
+checksum = "0942ffc6dcaadf03badf6e6a2d0228460359d5e34b57ccdc720b7382dfbd5ec5"
 
 [[package]]
 name = "cc"
-version = "1.0.79"
+version = "1.0.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "50d30906286121d95be3d479533b458f87493b30a4b5f79a607db8f5d11aa91f"
+checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
+dependencies = [
+ "libc",
+]
 
 [[package]]
 name = "cfg-if"
@@ -58,9 +61,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.103"
+version = "0.1.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3b73c3443a5fd2438d7ba4853c64e4c8efc2404a9e28a9234cc2d5eebc6c242"
+checksum = "99c3f9035afc33f4358773239573f7d121099856753e1bbd2a6a5207098fc741"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",
@@ -124,9 +127,9 @@ dependencies = [
 
 [[package]]
 name = "gimli"
-version = "0.28.0"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6fb8d784f27acf97159b40fc4db5ecd8aa23b9ad5ef69cdd136d3bc80665f0c0"
+checksum = "4271d37baee1b8c7e4b708028c57d816cf9d2434acb33a549475f78c181f6253"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-alloc",
@@ -135,9 +138,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.14.0"
+version = "0.14.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2c6201b9ff9fd90a5a3bac2e56a830d0caa509576f0e503818ee82c181b3437a"
+checksum = "290f1a1d9242c78d09ce40a5e87e7554ee637af1351968159f4952f028f75604"
 dependencies = [
  "allocator-api2",
  "compiler_builtins",
@@ -147,9 +150,9 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "443144c8cdadd93ebf52ddb4056d257f5b52c04d3c804e657d19eb73fc33668b"
+checksum = "d77f7ec81a6d05a3abb01ab6eb7590f6083d08449fe5a1c8b1e620283546ccb7"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-alloc",
@@ -167,9 +170,9 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.5.0"
+version = "2.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-core",
@@ -189,9 +192,9 @@ dependencies = [
 
 [[package]]
 name = "object"
-version = "0.32.0"
+version = "0.32.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77ac5bbd07aea88c60a577a1ce218075ffd59208b2d7ca97adf9bfc5aeb21ebe"
+checksum = "9cf5f9dd3933bd50a9e1f149ec995f39ae2c496d31fd772c1fd45ebc27e902b0"
 dependencies = [
  "compiler_builtins",
  "memchr",
@@ -241,9 +244,9 @@ dependencies = [
 
 [[package]]
 name = "r-efi"
-version = "4.2.0"
+version = "4.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "575fc2d9b3da54adbdfaddf6eca48fec256d977c8630a1750b8991347d1ac911"
+checksum = "0e244f96e03a3067f9e521d3167bd42657594cb8588c8d3a2db01545dc1af2e0"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-core",
@@ -402,9 +405,9 @@ dependencies = [
 
 [[package]]
 name = "unicode-width"
-version = "0.1.10"
+version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c0edd1e5b14653f783770bce4a4dabb4a5108a5370a5f5d8cfe8710c361f6c8b"
+checksum = "e51733f11c9c4f72aa0c160008246859e340b00807569a0da0e7a1079b27ba85"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-core",
@@ -419,6 +422,18 @@ dependencies = [
  "compiler_builtins",
  "core",
  "libc",
+ "unwinding",
+]
+
+[[package]]
+name = "unwinding"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37a19a21a537f635c16c7576f22d0f2f7d63353c1337ad4ce0d8001c7952a25b"
+dependencies = [
+ "compiler_builtins",
+ "gimli",
+ "rustc-std-workspace-core",
 ]
 
 [[package]]
diff --git a/rust-toolchain b/rust-toolchain
index 2997816d96c..4ba08f1af44 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-11-25"
+channel = "nightly-2023-12-19"
 components = ["rust-src", "rustc-dev", "llvm-tools"]
diff --git a/scripts/test_rustc_tests.sh b/scripts/test_rustc_tests.sh
index a299b6de6b1..7d7ffdadc7f 100755
--- a/scripts/test_rustc_tests.sh
+++ b/scripts/test_rustc_tests.sh
@@ -44,6 +44,7 @@ rm tests/ui/proc-macro/no-mangle-in-proc-macro-issue-111888.rs
 # vendor intrinsics
 rm tests/ui/sse2.rs # CodegenBackend::target_features not yet implemented
 rm tests/ui/simd/array-type.rs # "Index argument for `simd_insert` is not a constant"
+rm tests/ui/simd/masked-load-store.rs
 
 # exotic linkages
 rm tests/ui/issues/issue-33992.rs # unsupported linkages
diff --git a/src/base.rs b/src/base.rs
index 8b0dc611075..df40a5eb475 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -353,7 +353,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                             fx,
                             rustc_hir::LangItem::PanicBoundsCheck,
                             &[index, len, location],
-                            source_info.span,
+                            Some(source_info.span),
                         );
                     }
                     AssertKind::MisalignedPointerDereference { ref required, ref found } => {
@@ -365,7 +365,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                             fx,
                             rustc_hir::LangItem::PanicMisalignedPointerDereference,
                             &[required, found, location],
-                            source_info.span,
+                            Some(source_info.span),
                         );
                     }
                     _ => {
@@ -945,19 +945,19 @@ pub(crate) fn codegen_panic<'tcx>(
     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
     let args = [msg_ptr, msg_len, location];
 
-    codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
+    codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, Some(source_info.span));
 }
 
 pub(crate) fn codegen_panic_nounwind<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     msg_str: &str,
-    source_info: mir::SourceInfo,
+    span: Option<Span>,
 ) {
     let msg_ptr = fx.anonymous_str(msg_str);
     let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
     let args = [msg_ptr, msg_len];
 
-    codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, source_info.span);
+    codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, span);
 }
 
 pub(crate) fn codegen_unwind_terminate<'tcx>(
@@ -967,16 +967,16 @@ pub(crate) fn codegen_unwind_terminate<'tcx>(
 ) {
     let args = [];
 
-    codegen_panic_inner(fx, reason.lang_item(), &args, source_info.span);
+    codegen_panic_inner(fx, reason.lang_item(), &args, Some(source_info.span));
 }
 
 fn codegen_panic_inner<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     lang_item: rustc_hir::LangItem,
     args: &[Value],
-    span: Span,
+    span: Option<Span>,
 ) {
-    let def_id = fx.tcx.require_lang_item(lang_item, Some(span));
+    let def_id = fx.tcx.require_lang_item(lang_item, span);
 
     let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
     let symbol_name = fx.tcx.symbol_name(instance).name;
diff --git a/src/common.rs b/src/common.rs
index 63562d33508..bd19a7ed059 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -98,11 +98,15 @@ fn clif_pair_type_from_ty<'tcx>(
 
 /// Is a pointer to this type a fat ptr?
 pub(crate) fn has_ptr_meta<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
-    let ptr_ty = Ty::new_ptr(tcx, TypeAndMut { ty, mutbl: rustc_hir::Mutability::Not });
-    match &tcx.layout_of(ParamEnv::reveal_all().and(ptr_ty)).unwrap().abi {
-        Abi::Scalar(_) => false,
-        Abi::ScalarPair(_, _) => true,
-        abi => unreachable!("Abi of ptr to {:?} is {:?}???", ty, abi),
+    if ty.is_sized(tcx, ParamEnv::reveal_all()) {
+        return false;
+    }
+
+    let tail = tcx.struct_tail_erasing_lifetimes(ty, ParamEnv::reveal_all());
+    match tail.kind() {
+        ty::Foreign(..) => false,
+        ty::Str | ty::Slice(..) | ty::Dynamic(..) => true,
+        _ => bug!("unexpected unsized tail: {:?}", tail),
     }
 }
 
diff --git a/src/intrinsics/mod.rs b/src/intrinsics/mod.rs
index bfeeb117ff5..68126f12424 100644
--- a/src/intrinsics/mod.rs
+++ b/src/intrinsics/mod.rs
@@ -487,13 +487,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
             let layout = fx.layout_of(generic_args.type_at(0));
             // Note: Can't use is_unsized here as truly unsized types need to take the fixed size
             // branch
-            let size = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
-                let (_ptr, info) = ptr.load_scalar_pair(fx);
-                let (size, _align) = crate::unsize::size_and_align_of_dst(fx, layout, info);
-                size
+            let meta = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
+                Some(ptr.load_scalar_pair(fx).1)
             } else {
-                fx.bcx.ins().iconst(fx.pointer_type, layout.size.bytes() as i64)
+                None
             };
+            let (size, _align) = crate::unsize::size_and_align_of(fx, layout, meta);
             ret.write_cvalue(fx, CValue::by_val(size, usize_layout));
         }
         sym::min_align_of_val => {
@@ -502,13 +501,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
             let layout = fx.layout_of(generic_args.type_at(0));
             // Note: Can't use is_unsized here as truly unsized types need to take the fixed size
             // branch
-            let align = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
-                let (_ptr, info) = ptr.load_scalar_pair(fx);
-                let (_size, align) = crate::unsize::size_and_align_of_dst(fx, layout, info);
-                align
+            let meta = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
+                Some(ptr.load_scalar_pair(fx).1)
             } else {
-                fx.bcx.ins().iconst(fx.pointer_type, layout.align.abi.bytes() as i64)
+                None
             };
+            let (_size, align) = crate::unsize::size_and_align_of(fx, layout, meta);
             ret.write_cvalue(fx, CValue::by_val(align, usize_layout));
         }
 
@@ -688,7 +686,7 @@ fn codegen_regular_intrinsic_call<'tcx>(
                             }
                         })
                     });
-                    crate::base::codegen_panic_nounwind(fx, &msg_str, source_info);
+                    crate::base::codegen_panic_nounwind(fx, &msg_str, Some(source_info.span));
                     return;
                 }
             }
diff --git a/src/unsize.rs b/src/unsize.rs
index c6133f2b35c..f777e11371f 100644
--- a/src/unsize.rs
+++ b/src/unsize.rs
@@ -2,6 +2,9 @@
 //!
 //! [`PointerCoercion::Unsize`]: `rustc_middle::ty::adjustment::PointerCoercion::Unsize`
 
+use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
+
+use crate::base::codegen_panic_nounwind;
 use crate::prelude::*;
 
 // Adapted from https://github.com/rust-lang/rust/blob/2a663555ddf36f6b041445894a8c175cd1bc718c/src/librustc_codegen_ssa/base.rs#L159-L307
@@ -187,63 +190,113 @@ pub(crate) fn coerce_dyn_star<'tcx>(
 
 // Adapted from https://github.com/rust-lang/rust/blob/2a663555ddf36f6b041445894a8c175cd1bc718c/src/librustc_codegen_ssa/glue.rs
 
-pub(crate) fn size_and_align_of_dst<'tcx>(
+pub(crate) fn size_and_align_of<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     layout: TyAndLayout<'tcx>,
-    info: Value,
+    info: Option<Value>,
 ) -> (Value, Value) {
-    assert!(layout.is_unsized() || layout.abi == Abi::Uninhabited);
-    match layout.ty.kind() {
+    if layout.is_sized() {
+        return (
+            fx.bcx.ins().iconst(fx.pointer_type, layout.size.bytes() as i64),
+            fx.bcx.ins().iconst(fx.pointer_type, layout.align.abi.bytes() as i64),
+        );
+    }
+
+    let ty = layout.ty;
+    match ty.kind() {
         ty::Dynamic(..) => {
             // load size/align from vtable
-            (crate::vtable::size_of_obj(fx, info), crate::vtable::min_align_of_obj(fx, info))
+            (
+                crate::vtable::size_of_obj(fx, info.unwrap()),
+                crate::vtable::min_align_of_obj(fx, info.unwrap()),
+            )
         }
         ty::Slice(_) | ty::Str => {
             let unit = layout.field(fx, 0);
             // The info in this case is the length of the str, so the size is that
             // times the unit size.
             (
-                fx.bcx.ins().imul_imm(info, unit.size.bytes() as i64),
+                fx.bcx.ins().imul_imm(info.unwrap(), unit.size.bytes() as i64),
                 fx.bcx.ins().iconst(fx.pointer_type, unit.align.abi.bytes() as i64),
             )
         }
-        _ => {
+        ty::Foreign(_) => {
+            let trap_block = fx.bcx.create_block();
+            let true_ = fx.bcx.ins().iconst(types::I8, 1);
+            let next_block = fx.bcx.create_block();
+            fx.bcx.ins().brif(true_, trap_block, &[], next_block, &[]);
+            fx.bcx.seal_block(trap_block);
+            fx.bcx.seal_block(next_block);
+            fx.bcx.switch_to_block(trap_block);
+
+            // `extern` type. We cannot compute the size, so panic.
+            let msg_str = with_no_visible_paths!({
+                with_no_trimmed_paths!({
+                    format!("attempted to compute the size or alignment of extern type `{ty}`")
+                })
+            });
+
+            codegen_panic_nounwind(fx, &msg_str, None);
+
+            fx.bcx.switch_to_block(next_block);
+
+            // This function does not return so we can now return whatever we want.
+            let size = fx.bcx.ins().iconst(fx.pointer_type, 42);
+            let align = fx.bcx.ins().iconst(fx.pointer_type, 42);
+            (size, align)
+        }
+        ty::Adt(..) | ty::Tuple(..) => {
             // First get the size of all statically known fields.
             // Don't use size_of because it also rounds up to alignment, which we
             // want to avoid, as the unsized field's alignment could be smaller.
             assert!(!layout.ty.is_simd());
 
             let i = layout.fields.count() - 1;
-            let sized_size = layout.fields.offset(i).bytes();
+            let unsized_offset_unadjusted = layout.fields.offset(i).bytes();
+            let unsized_offset_unadjusted =
+                fx.bcx.ins().iconst(fx.pointer_type, unsized_offset_unadjusted as i64);
             let sized_align = layout.align.abi.bytes();
             let sized_align = fx.bcx.ins().iconst(fx.pointer_type, sized_align as i64);
 
             // Recurse to get the size of the dynamically sized field (must be
             // the last field).
             let field_layout = layout.field(fx, i);
-            let (unsized_size, mut unsized_align) = size_and_align_of_dst(fx, field_layout, info);
+            let (unsized_size, mut unsized_align) = size_and_align_of(fx, field_layout, info);
 
-            // FIXME (#26403, #27023): We should be adding padding
-            // to `sized_size` (to accommodate the `unsized_align`
-            // required of the unsized field that follows) before
-            // summing it with `sized_size`. (Note that since #26403
-            // is unfixed, we do not yet add the necessary padding
-            // here. But this is where the add would go.)
+            // # First compute the dynamic alignment
 
-            // Return the sum of sizes and max of aligns.
-            let size = fx.bcx.ins().iadd_imm(unsized_size, sized_size as i64);
-
-            // Packed types ignore the alignment of their fields.
-            if let ty::Adt(def, _) = layout.ty.kind() {
-                if def.repr().packed() {
-                    unsized_align = sized_align;
+            // For packed types, we need to cap the alignment.
+            if let ty::Adt(def, _) = ty.kind() {
+                if let Some(packed) = def.repr().pack {
+                    if packed.bytes() == 1 {
+                        // We know this will be capped to 1.
+                        unsized_align = fx.bcx.ins().iconst(fx.pointer_type, 1);
+                    } else {
+                        // We have to dynamically compute `min(unsized_align, packed)`.
+                        let packed = fx.bcx.ins().iconst(fx.pointer_type, packed.bytes() as i64);
+                        let cmp = fx.bcx.ins().icmp(IntCC::UnsignedLessThan, unsized_align, packed);
+                        unsized_align = fx.bcx.ins().select(cmp, unsized_align, packed);
+                    }
                 }
             }
 
             // Choose max of two known alignments (combined value must
             // be aligned according to more restrictive of the two).
             let cmp = fx.bcx.ins().icmp(IntCC::UnsignedGreaterThan, sized_align, unsized_align);
-            let align = fx.bcx.ins().select(cmp, sized_align, unsized_align);
+            let full_align = fx.bcx.ins().select(cmp, sized_align, unsized_align);
+
+            // # Then compute the dynamic size
+
+            // The full formula for the size would be:
+            // let unsized_offset_adjusted = unsized_offset_unadjusted.align_to(unsized_align);
+            // let full_size = (unsized_offset_adjusted + unsized_size).align_to(full_align);
+            // However, `unsized_size` is a multiple of `unsized_align`.
+            // Therefore, we can equivalently do the `align_to(unsized_align)` *after* adding `unsized_size`:
+            // let full_size = (unsized_offset_unadjusted + unsized_size).align_to(unsized_align).align_to(full_align);
+            // Furthermore, `align >= unsized_align`, and therefore we only need to do:
+            // let full_size = (unsized_offset_unadjusted + unsized_size).align_to(full_align);
+
+            let full_size = fx.bcx.ins().iadd(unsized_offset_unadjusted, unsized_size);
 
             // Issue #27023: must add any necessary padding to `size`
             // (to make it a multiple of `align`) before returning it.
@@ -255,12 +308,13 @@ pub(crate) fn size_and_align_of_dst<'tcx>(
             // emulated via the semi-standard fast bit trick:
             //
             //   `(size + (align-1)) & -align`
-            let addend = fx.bcx.ins().iadd_imm(align, -1);
-            let add = fx.bcx.ins().iadd(size, addend);
-            let neg = fx.bcx.ins().ineg(align);
-            let size = fx.bcx.ins().band(add, neg);
+            let addend = fx.bcx.ins().iadd_imm(full_align, -1);
+            let add = fx.bcx.ins().iadd(full_size, addend);
+            let neg = fx.bcx.ins().ineg(full_align);
+            let full_size = fx.bcx.ins().band(add, neg);
 
-            (size, align)
+            (full_size, full_align)
         }
+        _ => bug!("size_and_align_of_dst: {ty} not supported"),
     }
 }
diff --git a/src/value_and_place.rs b/src/value_and_place.rs
index f52f59716a8..567a5669d49 100644
--- a/src/value_and_place.rs
+++ b/src/value_and_place.rs
@@ -20,34 +20,36 @@ fn codegen_field<'tcx>(
         (base.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap()), field_layout)
     };
 
-    if let Some(extra) = extra {
-        if field_layout.is_sized() {
-            return simple(fx);
-        }
-        match field_layout.ty.kind() {
-            ty::Slice(..) | ty::Str | ty::Foreign(..) => simple(fx),
-            ty::Adt(def, _) if def.repr().packed() => {
-                assert_eq!(layout.align.abi.bytes(), 1);
-                simple(fx)
-            }
-            _ => {
-                // We have to align the offset for DST's
-                let unaligned_offset = field_offset.bytes();
-                let (_, unsized_align) =
-                    crate::unsize::size_and_align_of_dst(fx, field_layout, extra);
+    if field_layout.is_sized() {
+        return simple(fx);
+    }
+    match field_layout.ty.kind() {
+        ty::Slice(..) | ty::Str => simple(fx),
+        _ => {
+            let unaligned_offset = field_offset.bytes();
 
-                let one = fx.bcx.ins().iconst(fx.pointer_type, 1);
-                let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
-                let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
-                let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
-                let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
-                let offset = fx.bcx.ins().band(and_lhs, and_rhs);
+            // Get the alignment of the field
+            let (_, mut unsized_align) = crate::unsize::size_and_align_of(fx, field_layout, extra);
 
-                (base.offset_value(fx, offset), field_layout)
+            // For packed types, we need to cap alignment.
+            if let ty::Adt(def, _) = layout.ty.kind() {
+                if let Some(packed) = def.repr().pack {
+                    let packed = fx.bcx.ins().iconst(fx.pointer_type, packed.bytes() as i64);
+                    let cmp = fx.bcx.ins().icmp(IntCC::UnsignedLessThan, unsized_align, packed);
+                    unsized_align = fx.bcx.ins().select(cmp, unsized_align, packed);
+                }
             }
+
+            // Bump the unaligned offset up to the appropriate alignment
+            let one = fx.bcx.ins().iconst(fx.pointer_type, 1);
+            let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
+            let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
+            let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
+            let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
+            let offset = fx.bcx.ins().band(and_lhs, and_rhs);
+
+            (base.offset_value(fx, offset), field_layout)
         }
-    } else {
-        simple(fx)
     }
 }
 
@@ -731,13 +733,8 @@ pub(crate) fn place_field(
         };
 
         let (field_ptr, field_layout) = codegen_field(fx, base, extra, layout, field);
-        if field_layout.is_unsized() {
-            if let ty::Foreign(_) = field_layout.ty.kind() {
-                assert!(extra.is_none());
-                CPlace::for_ptr(field_ptr, field_layout)
-            } else {
-                CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
-            }
+        if has_ptr_meta(fx.tcx, field_layout.ty) {
+            CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
         } else {
             CPlace::for_ptr(field_ptr, field_layout)
         }
diff --git a/y.cmd b/y.cmd
new file mode 100644
index 00000000000..e9b688645a4
--- /dev/null
+++ b/y.cmd
@@ -0,0 +1,9 @@
+@echo off
+echo [BUILD] build system >&2
+mkdir build 2>nul
+rustc build_system/main.rs -o build\y.exe -Cdebuginfo=1 --edition 2021 || goto :error
+build\y.exe %* || goto :error
+goto :EOF
+
+:error
+exit /b
diff --git a/y.ps1 b/y.ps1
new file mode 100644
index 00000000000..02ef0fcbd50
--- /dev/null
+++ b/y.ps1
@@ -0,0 +1,12 @@
+$ErrorActionPreference = "Stop"
+
+$host.ui.WriteErrorLine("[BUILD] build system")
+New-Item -ItemType Directory -Force -Path build | Out-Null
+& rustc build_system/main.rs -o build\y.exe -Cdebuginfo=1 --edition 2021
+if ($LASTEXITCODE -ne 0) {
+    exit $LASTEXITCODE
+}
+& build\y.exe $args
+if ($LASTEXITCODE -ne 0) {
+    exit $LASTEXITCODE
+}