diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs index de4b5a46c81aa..5bd73502d980a 100644 --- a/compiler/rustc_abi/src/lib.rs +++ b/compiler/rustc_abi/src/lib.rs @@ -43,7 +43,7 @@ use std::fmt; #[cfg(feature = "nightly")] use std::iter::Step; use std::num::{NonZeroUsize, ParseIntError}; -use std::ops::{Add, AddAssign, Deref, Mul, RangeInclusive, Sub}; +use std::ops::{Add, AddAssign, Deref, Mul, RangeFull, RangeInclusive, Sub}; use std::str::FromStr; use bitflags::bitflags; @@ -1391,12 +1391,45 @@ impl WrappingRange { } /// Returns `true` if `size` completely fills the range. + /// + /// Note that this is *not* the same as `self == WrappingRange::full(size)`. + /// Niche calculations can produce full ranges which are not the canonical one; + /// for example `Option>` gets `valid_range: (..=0) | (1..)`. #[inline] fn is_full_for(&self, size: Size) -> bool { let max_value = size.unsigned_int_max(); debug_assert!(self.start <= max_value && self.end <= max_value); self.start == (self.end.wrapping_add(1) & max_value) } + + /// Checks whether this range is considered non-wrapping when the values are + /// interpreted as *unsigned* numbers of width `size`. + /// + /// Returns `Ok(true)` if there's no wrap-around, `Ok(false)` if there is, + /// and `Err(..)` if the range is full so it depends how you think about it. + #[inline] + pub fn no_unsigned_wraparound(&self, size: Size) -> Result { + if self.is_full_for(size) { Err(..) } else { Ok(self.start <= self.end) } + } + + /// Checks whether this range is considered non-wrapping when the values are + /// interpreted as *signed* numbers of width `size`. + /// + /// This is heavily dependent on the `size`, as `100..=200` does wrap when + /// interpreted as `i8`, but doesn't when interpreted as `i16`. + /// + /// Returns `Ok(true)` if there's no wrap-around, `Ok(false)` if there is, + /// and `Err(..)` if the range is full so it depends how you think about it. + #[inline] + pub fn no_signed_wraparound(&self, size: Size) -> Result { + if self.is_full_for(size) { + Err(..) + } else { + let start: i128 = size.sign_extend(self.start); + let end: i128 = size.sign_extend(self.end); + Ok(start <= end) + } + } } impl fmt::Debug for WrappingRange { diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs index b0d191528a891..6a3fdb6ede18f 100644 --- a/compiler/rustc_codegen_ssa/src/mir/operand.rs +++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs @@ -486,6 +486,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> { // value and the variant index match, since that's all `Niche` can encode. let relative_max = niche_variants.end().as_u32() - niche_variants.start().as_u32(); + let niche_start_const = bx.cx().const_uint_big(tag_llty, niche_start); // We have a subrange `niche_start..=niche_end` inside `range`. // If the value of the tag is inside this subrange, it's a @@ -511,35 +512,88 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> { // } else { // untagged_variant // } - let niche_start = bx.cx().const_uint_big(tag_llty, niche_start); - let is_niche = bx.icmp(IntPredicate::IntEQ, tag, niche_start); + let is_niche = bx.icmp(IntPredicate::IntEQ, tag, niche_start_const); let tagged_discr = bx.cx().const_uint(cast_to, niche_variants.start().as_u32() as u64); (is_niche, tagged_discr, 0) } else { - // The special cases don't apply, so we'll have to go with - // the general algorithm. - let relative_discr = bx.sub(tag, bx.cx().const_uint_big(tag_llty, niche_start)); + // With multiple niched variants we'll have to actually compute + // the variant index from the stored tag. + // + // However, there's still one small optimization we can often do for + // determining *whether* a tag value is a natural value or a niched + // variant. The general algorithm involves a subtraction that often + // wraps in practice, making it tricky to analyse. However, in cases + // where there are few enough possible values of the tag that it doesn't + // need to wrap around, we can instead just look for the contiguous + // tag values on the end of the range with a single comparison. + // + // For example, take the type `enum Demo { A, B, Untagged(bool) }`. + // The `bool` is {0, 1}, and the two other variants are given the + // tags {2, 3} respectively. That means the `tag_range` is + // `[0, 3]`, which doesn't wrap as unsigned (nor as signed), so + // we can test for the niched variants with just `>= 2`. + // + // That means we're looking either for the niche values *above* + // the natural values of the untagged variant: + // + // niche_start niche_end + // | | + // v v + // MIN -------------+---------------------------+---------- MAX + // ^ | is niche | + // | +---------------------------+ + // | | + // tag_range.start tag_range.end + // + // Or *below* the natural values: + // + // niche_start niche_end + // | | + // v v + // MIN ----+-----------------------+---------------------- MAX + // | is niche | ^ + // +-----------------------+ | + // | | + // tag_range.start tag_range.end + // + // With those two options and having the flexibility to choose + // between a signed or unsigned comparison on the tag, that + // covers most realistic scenarios. The tests have a (contrived) + // example of a 1-byte enum with over 128 niched variants which + // wraps both as signed as unsigned, though, and for something + // like that we're stuck with the general algorithm. + + let tag_range = tag_scalar.valid_range(&dl); + let tag_size = tag_scalar.size(&dl); + let niche_end = u128::from(relative_max).wrapping_add(niche_start); + let niche_end = tag_size.truncate(niche_end); + + let relative_discr = bx.sub(tag, niche_start_const); let cast_tag = bx.intcast(relative_discr, cast_to, false); - let is_niche = bx.icmp( - IntPredicate::IntULE, - relative_discr, - bx.cx().const_uint(tag_llty, relative_max as u64), - ); - - // Thanks to parameter attributes and load metadata, LLVM already knows - // the general valid range of the tag. It's possible, though, for there - // to be an impossible value *in the middle*, which those ranges don't - // communicate, so it's worth an `assume` to let the optimizer know. - if niche_variants.contains(&untagged_variant) - && bx.cx().sess().opts.optimize != OptLevel::No - { - let impossible = - u64::from(untagged_variant.as_u32() - niche_variants.start().as_u32()); - let impossible = bx.cx().const_uint(tag_llty, impossible); - let ne = bx.icmp(IntPredicate::IntNE, relative_discr, impossible); - bx.assume(ne); - } + let is_niche = if tag_range.no_unsigned_wraparound(tag_size) == Ok(true) { + if niche_start == tag_range.start { + let niche_end_const = bx.cx().const_uint_big(tag_llty, niche_end); + bx.icmp(IntPredicate::IntULE, tag, niche_end_const) + } else { + assert_eq!(niche_end, tag_range.end); + bx.icmp(IntPredicate::IntUGE, tag, niche_start_const) + } + } else if tag_range.no_signed_wraparound(tag_size) == Ok(true) { + if niche_start == tag_range.start { + let niche_end_const = bx.cx().const_uint_big(tag_llty, niche_end); + bx.icmp(IntPredicate::IntSLE, tag, niche_end_const) + } else { + assert_eq!(niche_end, tag_range.end); + bx.icmp(IntPredicate::IntSGE, tag, niche_start_const) + } + } else { + bx.icmp( + IntPredicate::IntULE, + relative_discr, + bx.cx().const_uint(tag_llty, relative_max as u64), + ) + }; (is_niche, cast_tag, niche_variants.start().as_u32() as u128) }; @@ -550,11 +604,24 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> { bx.add(tagged_discr, bx.cx().const_uint_big(cast_to, delta)) }; - let discr = bx.select( - is_niche, - tagged_discr, - bx.cx().const_uint(cast_to, untagged_variant.as_u32() as u64), - ); + let untagged_variant_const = + bx.cx().const_uint(cast_to, u64::from(untagged_variant.as_u32())); + + // Thanks to parameter attributes and load metadata, LLVM already knows + // the general valid range of the tag. It's possible, though, for there + // to be an impossible value *in the middle*, which those ranges don't + // communicate, so it's worth an `assume` to let the optimizer know. + // Most importantly, this means when optimizing a variant test like + // `SELECT(is_niche, complex, CONST) == CONST` it's ok to simplify that + // to `!is_niche` because the `complex` part can't possibly match. + if niche_variants.contains(&untagged_variant) + && bx.cx().sess().opts.optimize != OptLevel::No + { + let ne = bx.icmp(IntPredicate::IntNE, tagged_discr, untagged_variant_const); + bx.assume(ne); + } + + let discr = bx.select(is_niche, tagged_discr, untagged_variant_const); // In principle we could insert assumes on the possible range of `discr`, but // currently in LLVM this isn't worth it because the original `tag` will diff --git a/tests/codegen/enum/enum-discriminant-eq.rs b/tests/codegen/enum/enum-discriminant-eq.rs new file mode 100644 index 0000000000000..0494c5f551b33 --- /dev/null +++ b/tests/codegen/enum/enum-discriminant-eq.rs @@ -0,0 +1,223 @@ +//@ compile-flags: -Copt-level=3 -Zmerge-functions=disabled +//@ min-llvm-version: 20 +//@ only-64bit + +// The `derive(PartialEq)` on enums with field-less variants compares discriminants, +// so make sure we emit that in some reasonable way. + +#![crate_type = "lib"] +#![feature(ascii_char)] +#![feature(core_intrinsics)] +#![feature(repr128)] + +use std::ascii::Char as AC; +use std::cmp::Ordering; +use std::intrinsics::discriminant_value; +use std::num::NonZero; + +// A type that's bigger than `isize`, unlike the usual cases that have small tags. +#[repr(u128)] +pub enum Giant { + Two = 2, + Three = 3, + Four = 4, +} + +#[unsafe(no_mangle)] +pub fn opt_bool_eq_discr(a: Option, b: Option) -> bool { + // CHECK-LABEL: @opt_bool_eq_discr( + // CHECK: %[[A:.+]] = icmp ne i8 %a, 2 + // CHECK: %[[B:.+]] = icmp eq i8 %b, 2 + // CHECK: %[[R:.+]] = xor i1 %[[A]], %[[B]] + // CHECK: ret i1 %[[R]] + + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn opt_ord_eq_discr(a: Option, b: Option) -> bool { + // CHECK-LABEL: @opt_ord_eq_discr( + // CHECK: %[[A:.+]] = icmp ne i8 %a, 2 + // CHECK: %[[B:.+]] = icmp eq i8 %b, 2 + // CHECK: %[[R:.+]] = xor i1 %[[A]], %[[B]] + // CHECK: ret i1 %[[R]] + + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn opt_nz32_eq_discr(a: Option>, b: Option>) -> bool { + // CHECK-LABEL: @opt_nz32_eq_discr( + // CHECK: %[[A:.+]] = icmp ne i32 %a, 0 + // CHECK: %[[B:.+]] = icmp eq i32 %b, 0 + // CHECK: %[[R:.+]] = xor i1 %[[A]], %[[B]] + // CHECK: ret i1 %[[R]] + + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn opt_ac_eq_discr(a: Option, b: Option) -> bool { + // CHECK-LABEL: @opt_ac_eq_discr( + // CHECK: %[[A:.+]] = icmp ne i8 %a, -128 + // CHECK: %[[B:.+]] = icmp eq i8 %b, -128 + // CHECK: %[[R:.+]] = xor i1 %[[A]], %[[B]] + // CHECK: ret i1 %[[R]] + + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn opt_giant_eq_discr(a: Option, b: Option) -> bool { + // CHECK-LABEL: @opt_giant_eq_discr( + // CHECK: %[[A:.+]] = icmp ne i128 %a, 1 + // CHECK: %[[B:.+]] = icmp eq i128 %b, 1 + // CHECK: %[[R:.+]] = xor i1 %[[A]], %[[B]] + // CHECK: ret i1 %[[R]] + + discriminant_value(&a) == discriminant_value(&b) +} + +pub enum Mid { + Before, + Thing(T), + After, +} + +#[unsafe(no_mangle)] +pub fn mid_bool_eq_discr(a: Mid, b: Mid) -> bool { + // CHECK-LABEL: @mid_bool_eq_discr( + + // CHECK: %[[A_REL_DISCR:.+]] = add nsw i8 %a, -2 + // CHECK: %[[A_IS_NICHE:.+]] = icmp samesign ugt i8 %a, 1 + // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %[[A_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]]) + // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1 + + // CHECK: %[[B_REL_DISCR:.+]] = add nsw i8 %b, -2 + // CHECK: %[[B_IS_NICHE:.+]] = icmp samesign ugt i8 %b, 1 + // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %[[B_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]]) + // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1 + + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn mid_ord_eq_discr(a: Mid, b: Mid) -> bool { + // CHECK-LABEL: @mid_ord_eq_discr( + + // CHECK: %[[A_REL_DISCR:.+]] = add nsw i8 %a, -2 + // CHECK: %[[A_IS_NICHE:.+]] = icmp sgt i8 %a, 1 + // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %[[A_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]]) + // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1 + + // CHECK: %[[B_REL_DISCR:.+]] = add nsw i8 %b, -2 + // CHECK: %[[B_IS_NICHE:.+]] = icmp sgt i8 %b, 1 + // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %[[B_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]]) + // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1 + + // CHECK: %[[R:.+]] = icmp eq i8 %[[A_DISCR]], %[[B_DISCR]] + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn mid_nz32_eq_discr(a: Mid>, b: Mid>) -> bool { + // CHECK-LABEL: @mid_nz32_eq_discr( + // CHECK: %[[R:.+]] = icmp eq i32 %a.0, %b.0 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == discriminant_value(&b) +} + +#[unsafe(no_mangle)] +pub fn mid_ac_eq_discr(a: Mid, b: Mid) -> bool { + // CHECK-LABEL: @mid_ac_eq_discr( + + // CHECK: %[[A_REL_DISCR:.+]] = xor i8 %a, -128 + // CHECK: %[[A_IS_NICHE:.+]] = icmp slt i8 %a, 0 + // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i8 %a, -127 + // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]]) + // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i8 %[[A_REL_DISCR]], i8 1 + + // CHECK: %[[B_REL_DISCR:.+]] = xor i8 %b, -128 + // CHECK: %[[B_IS_NICHE:.+]] = icmp slt i8 %b, 0 + // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i8 %b, -127 + // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]]) + // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i8 %[[B_REL_DISCR]], i8 1 + + // CHECK: %[[R:.+]] = icmp eq i8 %[[A_DISCR]], %[[B_DISCR]] + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == discriminant_value(&b) +} + +// FIXME: This should be improved once our LLVM fork picks up the fix for +// +#[unsafe(no_mangle)] +pub fn mid_giant_eq_discr(a: Mid, b: Mid) -> bool { + // CHECK-LABEL: @mid_giant_eq_discr( + + // CHECK: %[[A_TRUNC:.+]] = trunc nuw nsw i128 %a to i64 + // CHECK: %[[A_REL_DISCR:.+]] = add nsw i64 %[[A_TRUNC]], -5 + // CHECK: %[[A_IS_NICHE:.+]] = icmp samesign ugt i128 %a, 4 + // CHECK: %[[A_NOT_HOLE:.+]] = icmp ne i64 %[[A_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[A_NOT_HOLE]]) + // CHECK: %[[A_DISCR:.+]] = select i1 %[[A_IS_NICHE]], i64 %[[A_REL_DISCR]], i64 1 + + // CHECK: %[[B_TRUNC:.+]] = trunc nuw nsw i128 %b to i64 + // CHECK: %[[B_REL_DISCR:.+]] = add nsw i64 %[[B_TRUNC]], -5 + // CHECK: %[[B_IS_NICHE:.+]] = icmp samesign ugt i128 %b, 4 + // CHECK: %[[B_NOT_HOLE:.+]] = icmp ne i64 %[[B_REL_DISCR]], 1 + // CHECK: tail call void @llvm.assume(i1 %[[B_NOT_HOLE]]) + // CHECK: %[[B_DISCR:.+]] = select i1 %[[B_IS_NICHE]], i64 %[[B_REL_DISCR]], i64 1 + + // CHECK: %[[R:.+]] = icmp eq i64 %[[A_DISCR]], %[[B_DISCR]] + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == discriminant_value(&b) +} + +// In niche-encoded enums, testing for the untagged variant should optimize to a +// straight-forward comparison looking for the natural range of the payload value. + +#[unsafe(no_mangle)] +pub fn mid_bool_is_thing(a: Mid) -> bool { + // CHECK-LABEL: @mid_bool_is_thing( + // CHECK: %[[R:.+]] = icmp samesign ult i8 %a, 2 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == 1 +} + +#[unsafe(no_mangle)] +pub fn mid_ord_is_thing(a: Mid) -> bool { + // CHECK-LABEL: @mid_ord_is_thing( + // CHECK: %[[R:.+]] = icmp slt i8 %a, 2 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == 1 +} + +#[unsafe(no_mangle)] +pub fn mid_nz32_is_thing(a: Mid>) -> bool { + // CHECK-LABEL: @mid_nz32_is_thing( + // CHECK: %[[R:.+]] = icmp eq i32 %a.0, 1 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == 1 +} + +#[unsafe(no_mangle)] +pub fn mid_ac_is_thing(a: Mid) -> bool { + // CHECK-LABEL: @mid_ac_is_thing( + // CHECK: %[[R:.+]] = icmp sgt i8 %a, -1 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == 1 +} + +#[unsafe(no_mangle)] +pub fn mid_giant_is_thing(a: Mid) -> bool { + // CHECK-LABEL: @mid_giant_is_thing( + // CHECK: %[[R:.+]] = icmp samesign ult i128 %a, 5 + // CHECK: ret i1 %[[R]] + discriminant_value(&a) == 1 +} diff --git a/tests/codegen/enum/enum-match.rs b/tests/codegen/enum/enum-match.rs index 98635008d068f..57db44ec74e8f 100644 --- a/tests/codegen/enum/enum-match.rs +++ b/tests/codegen/enum/enum-match.rs @@ -41,7 +41,7 @@ pub enum Enum1 { // CHECK-NEXT: start: // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2 // CHECK-NEXT: %[[REL_VAR_WIDE:.+]] = zext i8 %[[REL_VAR]] to i64 -// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 2 +// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp{{( samesign)?}} ugt i8 %0, 1 // CHECK-NEXT: %[[NICHE_DISCR:.+]] = add nuw nsw i64 %[[REL_VAR_WIDE]], 1 // CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i64 %[[NICHE_DISCR]], i64 0 // CHECK-NEXT: switch i64 %[[DISCR]] @@ -148,10 +148,10 @@ pub enum MiddleNiche { // CHECK-LABEL: define{{( dso_local)?}} noundef{{( range\(i8 -?[0-9]+, -?[0-9]+\))?}} i8 @match4(i8{{.+}}%0) // CHECK-NEXT: start: // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2 -// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 5 // CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 2 // CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]]) -// CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i8 %[[REL_VAR]], i8 2 +// CHECK-NEXT: %[[NOT_NICHE:.+]] = icmp{{( samesign)?}} ult i8 %0, 2 +// CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[NOT_NICHE]], i8 2, i8 %[[REL_VAR]] // CHECK-NEXT: switch i8 %[[DISCR]] #[no_mangle] pub fn match4(e: MiddleNiche) -> u8 { @@ -167,11 +167,10 @@ pub fn match4(e: MiddleNiche) -> u8 { // CHECK-LABEL: define{{.+}}i1 @match4_is_c(i8{{.+}}%e) // CHECK-NEXT: start -// CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %e, -2 -// CHECK-NEXT: %[[NOT_NICHE:.+]] = icmp ugt i8 %[[REL_VAR]], 4 -// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 2 +// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %e, 4 // CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]]) -// CHECK-NEXT: ret i1 %[[NOT_NICHE]] +// CHECK-NEXT: %[[IS_C:.+]] = icmp{{( samesign)?}} ult i8 %e, 2 +// CHECK-NEXT: ret i1 %[[IS_C]] #[no_mangle] pub fn match4_is_c(e: MiddleNiche) -> bool { // Before #139098, this couldn't optimize out the `select` because it looked @@ -453,10 +452,10 @@ pub enum HugeVariantIndex { // CHECK-NEXT: start: // CHECK-NEXT: %[[REL_VAR:.+]] = add{{( nsw)?}} i8 %0, -2 // CHECK-NEXT: %[[REL_VAR_WIDE:.+]] = zext i8 %[[REL_VAR]] to i64 -// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], 3 -// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i8 %[[REL_VAR]], 1 -// CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]]) +// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp{{( samesign)?}} ugt i8 %0, 1 // CHECK-NEXT: %[[NICHE_DISCR:.+]] = add nuw nsw i64 %[[REL_VAR_WIDE]], 257 +// CHECK-NEXT: %[[NOT_IMPOSSIBLE:.+]] = icmp ne i64 %[[NICHE_DISCR]], 258 +// CHECK-NEXT: call void @llvm.assume(i1 %[[NOT_IMPOSSIBLE]]) // CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i64 %[[NICHE_DISCR]], i64 258 // CHECK-NEXT: switch i64 %[[DISCR]], // CHECK-NEXT: i64 257, @@ -471,3 +470,310 @@ pub fn match5(e: HugeVariantIndex) -> u8 { Possible259 => 100, } } + +// Make an enum where the niche tags wrap both as signed and as unsigned, to hit +// the most-fallback case where there's just nothing smart to do. + +pub enum E10Through65 { + D10 = 10, + D11 = 11, + D12 = 12, + D13 = 13, + D14 = 14, + D15 = 15, + D16 = 16, + D17 = 17, + D18 = 18, + D19 = 19, + D20 = 20, + D21 = 21, + D22 = 22, + D23 = 23, + D24 = 24, + D25 = 25, + D26 = 26, + D27 = 27, + D28 = 28, + D29 = 29, + D30 = 30, + D31 = 31, + D32 = 32, + D33 = 33, + D34 = 34, + D35 = 35, + D36 = 36, + D37 = 37, + D38 = 38, + D39 = 39, + D40 = 40, + D41 = 41, + D42 = 42, + D43 = 43, + D44 = 44, + D45 = 45, + D46 = 46, + D47 = 47, + D48 = 48, + D49 = 49, + D50 = 50, + D51 = 51, + D52 = 52, + D53 = 53, + D54 = 54, + D55 = 55, + D56 = 56, + D57 = 57, + D58 = 58, + D59 = 59, + D60 = 60, + D61 = 61, + D62 = 62, + D63 = 63, + D64 = 64, + D65 = 65, +} + +pub enum Tricky { + Untagged(E10Through65), + V001, + V002, + V003, + V004, + V005, + V006, + V007, + V008, + V009, + V010, + V011, + V012, + V013, + V014, + V015, + V016, + V017, + V018, + V019, + V020, + V021, + V022, + V023, + V024, + V025, + V026, + V027, + V028, + V029, + V030, + V031, + V032, + V033, + V034, + V035, + V036, + V037, + V038, + V039, + V040, + V041, + V042, + V043, + V044, + V045, + V046, + V047, + V048, + V049, + V050, + V051, + V052, + V053, + V054, + V055, + V056, + V057, + V058, + V059, + V060, + V061, + V062, + V063, + V064, + V065, + V066, + V067, + V068, + V069, + V070, + V071, + V072, + V073, + V074, + V075, + V076, + V077, + V078, + V079, + V080, + V081, + V082, + V083, + V084, + V085, + V086, + V087, + V088, + V089, + V090, + V091, + V092, + V093, + V094, + V095, + V096, + V097, + V098, + V099, + V100, + V101, + V102, + V103, + V104, + V105, + V106, + V107, + V108, + V109, + V110, + V111, + V112, + V113, + V114, + V115, + V116, + V117, + V118, + V119, + V120, + V121, + V122, + V123, + V124, + V125, + V126, + V127, + V128, + V129, + V130, + V131, + V132, + V133, + V134, + V135, + V136, + V137, + V138, + V139, + V140, + V141, + V142, + V143, + V144, + V145, + V146, + V147, + V148, + V149, + V150, + V151, + V152, + V153, + V154, + V155, + V156, + V157, + V158, + V159, + V160, + V161, + V162, + V163, + V164, + V165, + V166, + V167, + V168, + V169, + V170, + V171, + V172, + V173, + V174, + V175, + V176, + V177, + V178, + V179, + V180, + V181, + V182, + V183, + V184, + V185, + V186, + V187, + V188, + V189, + V190, + V191, + V192, + V193, + V194, + V195, + V196, + V197, + V198, + V199, + V200, +} + +const _: () = assert!(std::intrinsics::discriminant_value(&Tricky::V100) == 100); + +// CHECK-LABEL: define noundef{{( range\(i8 [0-9]+, [0-9]+\))?}} i8 @discriminant6(i8 noundef %e) +// CHECK-NEXT: start: +// CHECK-NEXT: %[[REL_VAR:.+]] = add i8 %e, -66 +// CHECK-NEXT: %[[IS_NICHE:.+]] = icmp ult i8 %[[REL_VAR]], -56 +// CHECK-NEXT: %[[TAGGED_DISCR:.+]] = add i8 %e, -65 +// CHECK-NEXT: %[[DISCR:.+]] = select i1 %[[IS_NICHE]], i8 %[[TAGGED_DISCR]], i8 0 +// CHECK-NEXT: ret i8 %[[DISCR]] +#[no_mangle] +pub fn discriminant6(e: Tricky) -> u8 { + std::intrinsics::discriminant_value(&e) as _ +} + +// Case from , +// where sign-extension is important. + +pub enum OpenResult { + Ok(()), + Err(()), + TransportErr(TransportErr), +} + +#[repr(i32)] +pub enum TransportErr { + UnknownMethod = -2, +} + +#[no_mangle] +pub fn match7(result: OpenResult) -> u8 { + // CHECK-LABEL: define noundef{{( range\(i8 [0-9]+, [0-9]+\))?}} i8 @match7(i32{{.+}}%result) + // CHECK-NEXT: start: + // CHECK-NEXT: %[[NOT_OK:.+]] = icmp ne i32 %result, -1 + // CHECK-NEXT: %[[RET:.+]] = zext i1 %[[NOT_OK]] to i8 + // CHECK-NEXT: ret i8 %[[RET]] + match result { + OpenResult::Ok(()) => 0, + _ => 1, + } +}