diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index d91a118bc71a3..94a22d2893e10 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -240,13 +240,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 if let OperandValueKind::Immediate(to_scalar) = cast_kind
                     && from_scalar.size(self.cx) == to_scalar.size(self.cx)
                 {
-                    let from_backend_ty = bx.backend_type(operand.layout);
                     let to_backend_ty = bx.backend_type(cast);
                     Some(OperandValue::Immediate(self.transmute_immediate(
                         bx,
                         imm,
                         from_scalar,
-                        from_backend_ty,
                         to_scalar,
                         to_backend_ty,
                     )))
@@ -262,13 +260,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     && in_a.size(self.cx) == out_a.size(self.cx)
                     && in_b.size(self.cx) == out_b.size(self.cx)
                 {
-                    let in_a_ibty = bx.scalar_pair_element_backend_type(operand.layout, 0, false);
-                    let in_b_ibty = bx.scalar_pair_element_backend_type(operand.layout, 1, false);
                     let out_a_ibty = bx.scalar_pair_element_backend_type(cast, 0, false);
                     let out_b_ibty = bx.scalar_pair_element_backend_type(cast, 1, false);
                     Some(OperandValue::Pair(
-                        self.transmute_immediate(bx, imm_a, in_a, in_a_ibty, out_a, out_a_ibty),
-                        self.transmute_immediate(bx, imm_b, in_b, in_b_ibty, out_b, out_b_ibty),
+                        self.transmute_immediate(bx, imm_a, in_a, out_a, out_a_ibty),
+                        self.transmute_immediate(bx, imm_b, in_b, out_b, out_b_ibty),
                     ))
                 } else {
                     None
@@ -292,12 +288,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     ) -> Option<Bx::Value> {
         use abi::Primitive::*;
 
-        // When scalars are passed by value, there's no metadata recording their
-        // valid ranges. For example, `char`s are passed as just `i32`, with no
-        // way for LLVM to know that they're 0x10FFFF at most. Thus we assume
-        // the range of the input value too, not just the output range.
-        self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
-
         imm = match (from_scalar.primitive(), to_scalar.primitive()) {
             (Int(_, is_signed), Int(..)) => bx.intcast(imm, to_backend_ty, is_signed),
             (Float(_), Float(_)) => {
@@ -339,21 +329,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         bx: &mut Bx,
         mut imm: Bx::Value,
         from_scalar: abi::Scalar,
-        from_backend_ty: Bx::Type,
         to_scalar: abi::Scalar,
         to_backend_ty: Bx::Type,
     ) -> Bx::Value {
+        use abi::Primitive::*;
+
         assert_eq!(from_scalar.size(self.cx), to_scalar.size(self.cx));
 
-        use abi::Primitive::*;
         imm = bx.from_immediate(imm);
 
-        // When scalars are passed by value, there's no metadata recording their
-        // valid ranges. For example, `char`s are passed as just `i32`, with no
-        // way for LLVM to know that they're 0x10FFFF at most. Thus we assume
-        // the range of the input value too, not just the output range.
-        self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
-
         imm = match (from_scalar.primitive(), to_scalar.primitive()) {
             (Int(..) | Float(_), Int(..) | Float(_)) => bx.bitcast(imm, to_backend_ty),
             (Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
@@ -368,55 +352,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 bx.bitcast(int_imm, to_backend_ty)
             }
         };
-        self.assume_scalar_range(bx, imm, to_scalar, to_backend_ty);
         imm = bx.to_immediate_scalar(imm, to_scalar);
         imm
     }
 
-    fn assume_scalar_range(
-        &self,
-        bx: &mut Bx,
-        imm: Bx::Value,
-        scalar: abi::Scalar,
-        backend_ty: Bx::Type,
-    ) {
-        if matches!(self.cx.sess().opts.optimize, OptLevel::No | OptLevel::Less)
-            // For now, the critical niches are all over `Int`eger values.
-            // Should floating-point values or pointers ever get more complex
-            // niches, then this code will probably want to handle them too.
-            || !matches!(scalar.primitive(), abi::Primitive::Int(..))
-            || scalar.is_always_valid(self.cx)
-        {
-            return;
-        }
-
-        let abi::WrappingRange { start, end } = scalar.valid_range(self.cx);
-
-        if start <= end {
-            if start > 0 {
-                let low = bx.const_uint_big(backend_ty, start);
-                let cmp = bx.icmp(IntPredicate::IntUGE, imm, low);
-                bx.assume(cmp);
-            }
-
-            let type_max = scalar.size(self.cx).unsigned_int_max();
-            if end < type_max {
-                let high = bx.const_uint_big(backend_ty, end);
-                let cmp = bx.icmp(IntPredicate::IntULE, imm, high);
-                bx.assume(cmp);
-            }
-        } else {
-            let low = bx.const_uint_big(backend_ty, start);
-            let cmp_low = bx.icmp(IntPredicate::IntUGE, imm, low);
-
-            let high = bx.const_uint_big(backend_ty, end);
-            let cmp_high = bx.icmp(IntPredicate::IntULE, imm, high);
-
-            let or = bx.or(cmp_low, cmp_high);
-            bx.assume(or);
-        }
-    }
-
     pub fn codegen_rvalue_unsized(
         &mut self,
         bx: &mut Bx,
diff --git a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
index 379d2140c09c5..32725ef375bf0 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
@@ -8,12 +8,11 @@ use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
 use rustc_middle::ty::cast::{mir_cast_kind, CastTy};
-use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::util::IntTypeExt;
 use rustc_middle::ty::{self, Ty, UpvarArgs};
 use rustc_span::source_map::Spanned;
 use rustc_span::{Span, DUMMY_SP};
-use rustc_target::abi::{Abi, FieldIdx, Primitive};
+use rustc_target::abi::FieldIdx;
 use tracing::debug;
 
 use crate::build::expr::as_place::PlaceBase;
@@ -201,7 +200,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 {
                     let discr_ty = adt_def.repr().discr_type().to_ty(this.tcx);
                     let temp = unpack!(block = this.as_temp(block, scope, source, Mutability::Not));
-                    let layout = this.tcx.layout_of(this.param_env.and(source_expr.ty));
                     let discr = this.temp(discr_ty, source_expr.span);
                     this.cfg.push_assign(
                         block,
@@ -209,77 +207,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         discr,
                         Rvalue::Discriminant(temp.into()),
                     );
-                    let (op, ty) = (Operand::Move(discr), discr_ty);
-
-                    if let Abi::Scalar(scalar) = layout.unwrap().abi
-                        && !scalar.is_always_valid(&this.tcx)
-                        && let Primitive::Int(int_width, _signed) = scalar.primitive()
-                    {
-                        let unsigned_ty = int_width.to_ty(this.tcx, false);
-                        let unsigned_place = this.temp(unsigned_ty, expr_span);
-                        this.cfg.push_assign(
-                            block,
-                            source_info,
-                            unsigned_place,
-                            Rvalue::Cast(CastKind::IntToInt, Operand::Copy(discr), unsigned_ty),
-                        );
-
-                        let bool_ty = this.tcx.types.bool;
-                        let range = scalar.valid_range(&this.tcx);
-                        let merge_op =
-                            if range.start <= range.end { BinOp::BitAnd } else { BinOp::BitOr };
-
-                        let mut comparer = |range: u128, bin_op: BinOp| -> Place<'tcx> {
-                            let range_val = Const::from_bits(
-                                this.tcx,
-                                range,
-                                ty::ParamEnv::empty().and(unsigned_ty),
-                            );
-                            let lit_op = this.literal_operand(expr.span, range_val);
-                            let is_bin_op = this.temp(bool_ty, expr_span);
-                            this.cfg.push_assign(
-                                block,
-                                source_info,
-                                is_bin_op,
-                                Rvalue::BinaryOp(
-                                    bin_op,
-                                    Box::new((Operand::Copy(unsigned_place), lit_op)),
-                                ),
-                            );
-                            is_bin_op
-                        };
-                        let assert_place = if range.start == 0 {
-                            comparer(range.end, BinOp::Le)
-                        } else {
-                            let start_place = comparer(range.start, BinOp::Ge);
-                            let end_place = comparer(range.end, BinOp::Le);
-                            let merge_place = this.temp(bool_ty, expr_span);
-                            this.cfg.push_assign(
-                                block,
-                                source_info,
-                                merge_place,
-                                Rvalue::BinaryOp(
-                                    merge_op,
-                                    Box::new((
-                                        Operand::Move(start_place),
-                                        Operand::Move(end_place),
-                                    )),
-                                ),
-                            );
-                            merge_place
-                        };
-                        this.cfg.push(
-                            block,
-                            Statement {
-                                source_info,
-                                kind: StatementKind::Intrinsic(Box::new(
-                                    NonDivergingIntrinsic::Assume(Operand::Move(assert_place)),
-                                )),
-                            },
-                        );
-                    }
-
-                    (op, ty)
+                    (Operand::Move(discr), discr_ty)
                 } else {
                     let ty = source_expr.ty;
                     let source = unpack!(
diff --git a/src/tools/tidy/src/issues.txt b/src/tools/tidy/src/issues.txt
index 5731097770481..92840010250da 100644
--- a/src/tools/tidy/src/issues.txt
+++ b/src/tools/tidy/src/issues.txt
@@ -3628,7 +3628,6 @@ ui/regions/issue-56537-closure-uses-region-from-container.rs
 ui/regions/issue-6157.rs
 ui/regions/issue-72051-member-region-hang.rs
 ui/regions/issue-78262.rs
-ui/repr/issue-83505-repr-simd.rs
 ui/resolve/auxiliary/issue-112831-aux.rs
 ui/resolve/auxiliary/issue-19452-aux.rs
 ui/resolve/auxiliary/issue-21221-3.rs
diff --git a/tests/codegen/cast-optimized.rs b/tests/codegen/cast-optimized.rs
index 59cf40935cd54..f5dddfd7b4dd0 100644
--- a/tests/codegen/cast-optimized.rs
+++ b/tests/codegen/cast-optimized.rs
@@ -1,4 +1,5 @@
 //@ compile-flags: -O -Z merge-functions=disabled
+//@ min-llvm-version: 19
 #![crate_type = "lib"]
 
 // This tests that LLVM can optimize based on the niches in the source or
diff --git a/tests/codegen/enum/enum-bounds-check-derived-idx.rs b/tests/codegen/enum/enum-bounds-check-derived-idx.rs
index 15280cb2e6c87..b6e6411fedcd3 100644
--- a/tests/codegen/enum/enum-bounds-check-derived-idx.rs
+++ b/tests/codegen/enum/enum-bounds-check-derived-idx.rs
@@ -1,6 +1,7 @@
 // This test checks an optimization that is not guaranteed to work. This test case should not block
 // a future LLVM update.
 //@ compile-flags: -O
+//@ min-llvm-version: 19
 
 #![crate_type = "lib"]
 
diff --git a/tests/codegen/enum/enum-bounds-check-issue-13926.rs b/tests/codegen/enum/enum-bounds-check-issue-13926.rs
index b60ff38ce392c..9b2eaeff48cb4 100644
--- a/tests/codegen/enum/enum-bounds-check-issue-13926.rs
+++ b/tests/codegen/enum/enum-bounds-check-issue-13926.rs
@@ -1,6 +1,7 @@
 // This test checks an optimization that is not guaranteed to work. This test case should not block
 // a future LLVM update.
 //@ compile-flags: -O
+//@ min-llvm-version: 19
 
 #![crate_type = "lib"]
 
diff --git a/tests/codegen/enum/enum-bounds-check.rs b/tests/codegen/enum/enum-bounds-check.rs
index c44c007ed6a9f..013a5782851a7 100644
--- a/tests/codegen/enum/enum-bounds-check.rs
+++ b/tests/codegen/enum/enum-bounds-check.rs
@@ -1,4 +1,5 @@
 //@ compile-flags: -O
+//@ min-llvm-version: 19
 
 #![crate_type = "lib"]
 
diff --git a/tests/codegen/intrinsics/transmute-niched.rs b/tests/codegen/intrinsics/transmute-niched.rs
index f5b7bd2efea8e..46b013a2919c8 100644
--- a/tests/codegen/intrinsics/transmute-niched.rs
+++ b/tests/codegen/intrinsics/transmute-niched.rs
@@ -1,7 +1,5 @@
-//@ revisions: OPT DBG
-//@ [OPT] compile-flags: -C opt-level=3 -C no-prepopulate-passes
-//@ [DBG] compile-flags: -C opt-level=0 -C no-prepopulate-passes
-//@ only-64bit (so I don't need to worry about usize)
+//@ compile-flags: -C opt-level=3 -C no-prepopulate-passes
+//@ min-llvm-version: 19
 #![crate_type = "lib"]
 
 use std::mem::transmute;
@@ -14,59 +12,27 @@ pub enum SmallEnum {
     C = 12,
 }
 
-// CHECK-LABEL: @check_to_enum(
+// CHECK: noundef range(i8 10, 13) i8 @check_to_enum(
 #[no_mangle]
 pub unsafe fn check_to_enum(x: i8) -> SmallEnum {
-    // OPT: %0 = icmp uge i8 %x, 10
-    // OPT: call void @llvm.assume(i1 %0)
-    // OPT: %1 = icmp ule i8 %x, 12
-    // OPT: call void @llvm.assume(i1 %1)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i8 %x
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_from_enum(
+// CHECK: @check_from_enum(i8 noundef range(i8 10, 13) %x)
 #[no_mangle]
 pub unsafe fn check_from_enum(x: SmallEnum) -> i8 {
-    // OPT: %0 = icmp uge i8 %x, 10
-    // OPT: call void @llvm.assume(i1 %0)
-    // OPT: %1 = icmp ule i8 %x, 12
-    // OPT: call void @llvm.assume(i1 %1)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i8 %x
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_to_ordering(
+// CHECK: noundef range(i8 -1, 2) i8 @check_to_ordering(
 #[no_mangle]
 pub unsafe fn check_to_ordering(x: u8) -> std::cmp::Ordering {
-    // OPT: %0 = icmp uge i8 %x, -1
-    // OPT: %1 = icmp ule i8 %x, 1
-    // OPT: %2 = or i1 %0, %1
-    // OPT: call void @llvm.assume(i1 %2)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i8 %x
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_from_ordering(
+// CHECK: @check_from_ordering(i8 noundef range(i8 -1, 2) %x)
 #[no_mangle]
 pub unsafe fn check_from_ordering(x: std::cmp::Ordering) -> u8 {
-    // OPT: %0 = icmp uge i8 %x, -1
-    // OPT: %1 = icmp ule i8 %x, 1
-    // OPT: %2 = or i1 %0, %1
-    // OPT: call void @llvm.assume(i1 %2)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i8 %x
-
     transmute(x)
 }
 
@@ -95,88 +61,32 @@ pub enum Minus100ToPlus100 {
     U = 100,
 }
 
-// CHECK-LABEL: @check_enum_from_char(
+// CHECK: noundef range(i32 -100, 101) i32 @check_enum_from_char(i32 noundef range(i32 0, 1114112) %x)
 #[no_mangle]
 pub unsafe fn check_enum_from_char(x: char) -> Minus100ToPlus100 {
-    // OPT: %0 = icmp ule i32 %x, 1114111
-    // OPT: call void @llvm.assume(i1 %0)
-    // OPT: %1 = icmp uge i32 %x, -100
-    // OPT: %2 = icmp ule i32 %x, 100
-    // OPT: %3 = or i1 %1, %2
-    // OPT: call void @llvm.assume(i1 %3)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i32 %x
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_enum_to_char(
+// CHECK: noundef range(i32 0, 1114112) i32 @check_enum_to_char(i32 noundef range(i32 -100, 101) %x)
 #[no_mangle]
 pub unsafe fn check_enum_to_char(x: Minus100ToPlus100) -> char {
-    // OPT: %0 = icmp uge i32 %x, -100
-    // OPT: %1 = icmp ule i32 %x, 100
-    // OPT: %2 = or i1 %0, %1
-    // OPT: call void @llvm.assume(i1 %2)
-    // OPT: %3 = icmp ule i32 %x, 1114111
-    // OPT: call void @llvm.assume(i1 %3)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i32 %x
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_swap_pair(
+// CHECK: @check_swap_pair(i32 noundef range(i32 0, 1114112) %x.0, i32 noundef range(i32 1, 0) %x.1)
 #[no_mangle]
 pub unsafe fn check_swap_pair(x: (char, NonZero<u32>)) -> (NonZero<u32>, char) {
-    // OPT: %0 = icmp ule i32 %x.0, 1114111
-    // OPT: call void @llvm.assume(i1 %0)
-    // OPT: %1 = icmp uge i32 %x.0, 1
-    // OPT: call void @llvm.assume(i1 %1)
-    // OPT: %2 = icmp uge i32 %x.1, 1
-    // OPT: call void @llvm.assume(i1 %2)
-    // OPT: %3 = icmp ule i32 %x.1, 1114111
-    // OPT: call void @llvm.assume(i1 %3)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: %[[P1:.+]] = insertvalue { i32, i32 } poison, i32 %x.0, 0
-    // CHECK: %[[P2:.+]] = insertvalue { i32, i32 } %[[P1]], i32 %x.1, 1
-    // CHECK: ret { i32, i32 } %[[P2]]
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_bool_from_ordering(
+// CHECK: @check_bool_from_ordering(i8 noundef range(i8 -1, 2) %x)
 #[no_mangle]
 pub unsafe fn check_bool_from_ordering(x: std::cmp::Ordering) -> bool {
-    // OPT: %0 = icmp uge i8 %x, -1
-    // OPT: %1 = icmp ule i8 %x, 1
-    // OPT: %2 = or i1 %0, %1
-    // OPT: call void @llvm.assume(i1 %2)
-    // OPT: %3 = icmp ule i8 %x, 1
-    // OPT: call void @llvm.assume(i1 %3)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: %[[R:.+]] = trunc i8 %x to i1
-    // CHECK: ret i1 %[[R]]
-
     transmute(x)
 }
 
-// CHECK-LABEL: @check_bool_to_ordering(
+// CHECK: noundef range(i8 -1, 2) i8 @check_bool_to_ordering(
 #[no_mangle]
 pub unsafe fn check_bool_to_ordering(x: bool) -> std::cmp::Ordering {
-    // CHECK: %_0 = zext i1 %x to i8
-    // OPT: %0 = icmp ule i8 %_0, 1
-    // OPT: call void @llvm.assume(i1 %0)
-    // OPT: %1 = icmp uge i8 %_0, -1
-    // OPT: %2 = icmp ule i8 %_0, 1
-    // OPT: %3 = or i1 %1, %2
-    // OPT: call void @llvm.assume(i1 %3)
-    // DBG-NOT: icmp
-    // DBG-NOT: assume
-    // CHECK: ret i8 %_0
-
     transmute(x)
 }
diff --git a/tests/codegen/issues/issue-119422.rs b/tests/codegen/issues/issue-119422.rs
index 682430a79f4a9..44402fd94d363 100644
--- a/tests/codegen/issues/issue-119422.rs
+++ b/tests/codegen/issues/issue-119422.rs
@@ -3,6 +3,7 @@
 //!
 //@ compile-flags: -O --edition=2021 -Zmerge-functions=disabled
 //@ only-64bit (because the LLVM type of i64 for usize shows up)
+//@ min-llvm-version: 19
 #![crate_type = "lib"]
 
 use core::num::NonZero;
diff --git a/tests/codegen/transmute-optimized.rs b/tests/codegen/transmute-optimized.rs
index 11bd0523788a1..ed55f95661d4e 100644
--- a/tests/codegen/transmute-optimized.rs
+++ b/tests/codegen/transmute-optimized.rs
@@ -1,4 +1,5 @@
 //@ compile-flags: -O -Z merge-functions=disabled
+//@ min-llvm-version: 19
 #![crate_type = "lib"]
 
 // This tests that LLVM can optimize based on the niches in the source or
@@ -92,14 +93,14 @@ pub enum OneTwoThree {
 // CHECK-LABEL: i8 @ordering_transmute_onetwothree(i8
 #[no_mangle]
 pub unsafe fn ordering_transmute_onetwothree(x: std::cmp::Ordering) -> OneTwoThree {
-    // CHECK: ret i8 1
+    // CHECK: ret i8 %x
     std::mem::transmute(x)
 }
 
 // CHECK-LABEL: i8 @onetwothree_transmute_ordering(i8
 #[no_mangle]
 pub unsafe fn onetwothree_transmute_ordering(x: OneTwoThree) -> std::cmp::Ordering {
-    // CHECK: ret i8 1
+    // CHECK: ret i8 %x
     std::mem::transmute(x)
 }
 
diff --git a/tests/crashes/121097.rs b/tests/crashes/121097.rs
deleted file mode 100644
index 65c6028e03e36..0000000000000
--- a/tests/crashes/121097.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-//@ known-bug: #121097
-#[repr(simd)]
-enum Aligned {
-    Zero = 0,
-    One = 1,
-}
-
-fn tou8(al: Aligned) -> u8 {
-    al as u8
-}
diff --git a/tests/mir-opt/building/enum_cast.bar.built.after.mir b/tests/mir-opt/building/enum_cast.bar.built.after.mir
index 512c73216198e..0dc6448ffad01 100644
--- a/tests/mir-opt/building/enum_cast.bar.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.bar.built.after.mir
@@ -5,16 +5,11 @@ fn bar(_1: Bar) -> usize {
     let mut _0: usize;
     let _2: Bar;
     let mut _3: isize;
-    let mut _4: u8;
-    let mut _5: bool;
 
     bb0: {
         StorageLive(_2);
         _2 = move _1;
         _3 = discriminant(_2);
-        _4 = _3 as u8 (IntToInt);
-        _5 = Le(_4, const 1_u8);
-        assume(move _5);
         _0 = move _3 as usize (IntToInt);
         StorageDead(_2);
         return;
diff --git a/tests/mir-opt/building/enum_cast.boo.built.after.mir b/tests/mir-opt/building/enum_cast.boo.built.after.mir
index ad0adf14e4ac8..3540a2b1e2e47 100644
--- a/tests/mir-opt/building/enum_cast.boo.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.boo.built.after.mir
@@ -5,16 +5,11 @@ fn boo(_1: Boo) -> usize {
     let mut _0: usize;
     let _2: Boo;
     let mut _3: u8;
-    let mut _4: u8;
-    let mut _5: bool;
 
     bb0: {
         StorageLive(_2);
         _2 = move _1;
         _3 = discriminant(_2);
-        _4 = _3 as u8 (IntToInt);
-        _5 = Le(_4, const 1_u8);
-        assume(move _5);
         _0 = move _3 as usize (IntToInt);
         StorageDead(_2);
         return;
diff --git a/tests/mir-opt/building/enum_cast.droppy.built.after.mir b/tests/mir-opt/building/enum_cast.droppy.built.after.mir
index ea0edb610f5cc..65390605f740d 100644
--- a/tests/mir-opt/building/enum_cast.droppy.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.droppy.built.after.mir
@@ -6,9 +6,7 @@ fn droppy() -> () {
     let _2: Droppy;
     let _4: Droppy;
     let mut _5: isize;
-    let mut _6: u8;
-    let mut _7: bool;
-    let _8: Droppy;
+    let _6: Droppy;
     scope 1 {
         debug x => _2;
         scope 2 {
@@ -19,7 +17,7 @@ fn droppy() -> () {
         }
     }
     scope 4 {
-        debug z => _8;
+        debug z => _6;
     }
 
     bb0: {
@@ -31,9 +29,6 @@ fn droppy() -> () {
         StorageLive(_4);
         _4 = move _2;
         _5 = discriminant(_4);
-        _6 = _5 as u8 (IntToInt);
-        _7 = Le(_6, const 2_u8);
-        assume(move _7);
         _3 = move _5 as usize (IntToInt);
         drop(_4) -> [return: bb1, unwind: bb4];
     }
@@ -49,15 +44,15 @@ fn droppy() -> () {
     bb2: {
         StorageDead(_2);
         StorageDead(_1);
-        StorageLive(_8);
-        _8 = Droppy::B;
-        FakeRead(ForLet(None), _8);
+        StorageLive(_6);
+        _6 = Droppy::B;
+        FakeRead(ForLet(None), _6);
         _0 = const ();
-        drop(_8) -> [return: bb3, unwind: bb5];
+        drop(_6) -> [return: bb3, unwind: bb5];
     }
 
     bb3: {
-        StorageDead(_8);
+        StorageDead(_6);
         return;
     }
 
diff --git a/tests/mir-opt/building/enum_cast.far.built.after.mir b/tests/mir-opt/building/enum_cast.far.built.after.mir
index e75803c706daf..da34b7ba6c28a 100644
--- a/tests/mir-opt/building/enum_cast.far.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.far.built.after.mir
@@ -5,16 +5,11 @@ fn far(_1: Far) -> isize {
     let mut _0: isize;
     let _2: Far;
     let mut _3: i16;
-    let mut _4: u16;
-    let mut _5: bool;
 
     bb0: {
         StorageLive(_2);
         _2 = move _1;
         _3 = discriminant(_2);
-        _4 = _3 as u16 (IntToInt);
-        _5 = Le(_4, const 1_u16);
-        assume(move _5);
         _0 = move _3 as isize (IntToInt);
         StorageDead(_2);
         return;
diff --git a/tests/mir-opt/building/enum_cast.offsetty.built.after.mir b/tests/mir-opt/building/enum_cast.offsetty.built.after.mir
index 282859d7cd014..b84ce0de9a0a7 100644
--- a/tests/mir-opt/building/enum_cast.offsetty.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.offsetty.built.after.mir
@@ -5,20 +5,11 @@ fn offsetty(_1: NotStartingAtZero) -> u32 {
     let mut _0: u32;
     let _2: NotStartingAtZero;
     let mut _3: isize;
-    let mut _4: u8;
-    let mut _5: bool;
-    let mut _6: bool;
-    let mut _7: bool;
 
     bb0: {
         StorageLive(_2);
         _2 = move _1;
         _3 = discriminant(_2);
-        _4 = _3 as u8 (IntToInt);
-        _5 = Ge(_4, const 4_u8);
-        _6 = Le(_4, const 8_u8);
-        _7 = BitAnd(move _5, move _6);
-        assume(move _7);
         _0 = move _3 as u32 (IntToInt);
         StorageDead(_2);
         return;
diff --git a/tests/mir-opt/building/enum_cast.signy.built.after.mir b/tests/mir-opt/building/enum_cast.signy.built.after.mir
index a9f7d6c78007a..503c506748ff9 100644
--- a/tests/mir-opt/building/enum_cast.signy.built.after.mir
+++ b/tests/mir-opt/building/enum_cast.signy.built.after.mir
@@ -5,20 +5,11 @@ fn signy(_1: SignedAroundZero) -> i16 {
     let mut _0: i16;
     let _2: SignedAroundZero;
     let mut _3: i16;
-    let mut _4: u16;
-    let mut _5: bool;
-    let mut _6: bool;
-    let mut _7: bool;
 
     bb0: {
         StorageLive(_2);
         _2 = move _1;
         _3 = discriminant(_2);
-        _4 = _3 as u16 (IntToInt);
-        _5 = Ge(_4, const 65534_u16);
-        _6 = Le(_4, const 2_u16);
-        _7 = BitOr(move _5, move _6);
-        assume(move _7);
         _0 = move _3 as i16 (IntToInt);
         StorageDead(_2);
         return;
diff --git a/tests/ui/repr/issue-83505-repr-simd.rs b/tests/ui/repr/invalid-repr-simd.rs
similarity index 50%
rename from tests/ui/repr/issue-83505-repr-simd.rs
rename to tests/ui/repr/invalid-repr-simd.rs
index 280b771d01539..6d8f6ab7de633 100644
--- a/tests/ui/repr/issue-83505-repr-simd.rs
+++ b/tests/ui/repr/invalid-repr-simd.rs
@@ -1,4 +1,4 @@
-// Regression test for the ICE described in #83505.
+// Regression test for the ICEs described in #83505 & #121097.
 
 #![crate_type="lib"]
 
@@ -8,3 +8,14 @@
 enum Es {}
 static CLs: Es;
 //~^ ERROR: free static item without body
+
+#[repr(simd)]
+//~^ ERROR: attribute should be applied to a struct [E0517]
+enum Aligned {
+    Zero = 0,
+    One = 1,
+}
+
+pub fn tou8(al: Aligned) -> u8 {
+    al as u8
+}
diff --git a/tests/ui/repr/issue-83505-repr-simd.stderr b/tests/ui/repr/invalid-repr-simd.stderr
similarity index 61%
rename from tests/ui/repr/issue-83505-repr-simd.stderr
rename to tests/ui/repr/invalid-repr-simd.stderr
index df99baaf52293..67ba5d0131200 100644
--- a/tests/ui/repr/issue-83505-repr-simd.stderr
+++ b/tests/ui/repr/invalid-repr-simd.stderr
@@ -1,5 +1,5 @@
 error: free static item without body
-  --> $DIR/issue-83505-repr-simd.rs:9:1
+  --> $DIR/invalid-repr-simd.rs:9:1
    |
 LL | static CLs: Es;
    | ^^^^^^^^^^^^^^-
@@ -7,7 +7,7 @@ LL | static CLs: Es;
    |               help: provide a definition for the static: `= <expr>;`
 
 error[E0517]: attribute should be applied to a struct
-  --> $DIR/issue-83505-repr-simd.rs:5:8
+  --> $DIR/invalid-repr-simd.rs:5:8
    |
 LL | #[repr(simd)]
    |        ^^^^
@@ -15,8 +15,20 @@ LL | #[repr(simd)]
 LL | enum Es {}
    | ---------- not a struct
 
+error[E0517]: attribute should be applied to a struct
+  --> $DIR/invalid-repr-simd.rs:12:8
+   |
+LL |   #[repr(simd)]
+   |          ^^^^
+LL |
+LL | / enum Aligned {
+LL | |     Zero = 0,
+LL | |     One = 1,
+LL | | }
+   | |_- not a struct
+
 error[E0084]: unsupported representation for zero-variant enum
-  --> $DIR/issue-83505-repr-simd.rs:5:1
+  --> $DIR/invalid-repr-simd.rs:5:1
    |
 LL | #[repr(simd)]
    | ^^^^^^^^^^^^^
@@ -24,7 +36,7 @@ LL | #[repr(simd)]
 LL | enum Es {}
    | ------- zero-variant enum
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0084, E0517.
 For more information about an error, try `rustc --explain E0084`.
diff --git a/tests/ui/type-alias-enum-variants/self-in-enum-definition.stderr b/tests/ui/type-alias-enum-variants/self-in-enum-definition.stderr
index 084008d8b2a42..13ae6dfcaa354 100644
--- a/tests/ui/type-alias-enum-variants/self-in-enum-definition.stderr
+++ b/tests/ui/type-alias-enum-variants/self-in-enum-definition.stderr
@@ -7,36 +7,6 @@ LL |     V3 = Self::V1 {} as u8 + 2,
 note: ...which requires const-evaluating + checking `Alpha::V3::{constant#0}`...
   --> $DIR/self-in-enum-definition.rs:5:10
    |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires caching mir of `Alpha::V3::{constant#0}` for CTFE...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires elaborating drops for `Alpha::V3::{constant#0}`...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires borrow-checking `Alpha::V3::{constant#0}`...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires promoting constants in MIR for `Alpha::V3::{constant#0}`...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires const checking `Alpha::V3::{constant#0}`...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
-LL |     V3 = Self::V1 {} as u8 + 2,
-   |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires building MIR for `Alpha::V3::{constant#0}`...
-  --> $DIR/self-in-enum-definition.rs:5:10
-   |
 LL |     V3 = Self::V1 {} as u8 + 2,
    |          ^^^^^^^^^^^^^^^^^^^^^
    = note: ...which requires computing layout of `Alpha`...