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645c0fddd2
Previously, it was only put on scalars with range validity invariants like bool, was uninit was obviously invalid for those. Since then, we have normatively declared all uninit primitives to be undefined behavior and can therefore put `noundef` on them. The remaining concern was the `mem::uninitialized` function, which cause quite a lot of UB in the older parts of the ecosystem. This function now doesn't return uninit values anymore, making users of it safe from this change. The only real sources of UB where people could encounter uninit primitives are `MaybeUninit::uninit().assume_init()`, which has always be clear in the docs about being UB and from heap allocations (like reading from the spare capacity of a vec. This is hopefully rare enough to not break anything.
82 lines
2.7 KiB
Rust
82 lines
2.7 KiB
Rust
// compile-flags: -O -C no-prepopulate-passes
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#![crate_type = "lib"]
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// FIXME(eddyb) all of these tests show memory stores and loads, even after a
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// scalar `bitcast`, more special-casing is required to remove `alloca` usage.
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// CHECK-LABEL: define{{.*}}i32 @f32_to_bits(float noundef %x)
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// CHECK: store i32 %{{.*}}, {{.*}} %0
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// CHECK-NEXT: %[[RES:.*]] = load i32, {{.*}} %0
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// CHECK: ret i32 %[[RES]]
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#[no_mangle]
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pub fn f32_to_bits(x: f32) -> u32 {
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unsafe { std::mem::transmute(x) }
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}
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// CHECK-LABEL: define{{.*}}i8 @bool_to_byte(i1 noundef zeroext %b)
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// CHECK: %1 = zext i1 %b to i8
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// CHECK-NEXT: store i8 %1, {{.*}} %0
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// CHECK-NEXT: %2 = load i8, {{.*}} %0
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// CHECK: ret i8 %2
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#[no_mangle]
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pub fn bool_to_byte(b: bool) -> u8 {
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unsafe { std::mem::transmute(b) }
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}
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// CHECK-LABEL: define{{.*}}noundef zeroext i1 @byte_to_bool(i8 noundef %byte)
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// CHECK: %1 = trunc i8 %byte to i1
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// CHECK-NEXT: %2 = zext i1 %1 to i8
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// CHECK-NEXT: store i8 %2, {{.*}} %0
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// CHECK-NEXT: %3 = load i8, {{.*}} %0
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// CHECK-NEXT: %4 = trunc i8 %3 to i1
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// CHECK: ret i1 %4
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#[no_mangle]
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pub unsafe fn byte_to_bool(byte: u8) -> bool {
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std::mem::transmute(byte)
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}
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// CHECK-LABEL: define{{.*}}{{i8\*|ptr}} @ptr_to_ptr({{i16\*|ptr}} noundef %p)
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// CHECK: store {{i8\*|ptr}} %{{.*}}, {{.*}} %0
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// CHECK-NEXT: %[[RES:.*]] = load {{i8\*|ptr}}, {{.*}} %0
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// CHECK: ret {{i8\*|ptr}} %[[RES]]
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#[no_mangle]
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pub fn ptr_to_ptr(p: *mut u16) -> *mut u8 {
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unsafe { std::mem::transmute(p) }
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}
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// HACK(eddyb) scalar `transmute`s between pointers and non-pointers are
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// currently not special-cased like other scalar `transmute`s, because
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// LLVM requires specifically `ptrtoint`/`inttoptr` instead of `bitcast`.
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//
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// Tests below show the non-special-cased behavior (with the possible
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// future special-cased instructions in the "NOTE(eddyb)" comments).
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// CHECK: define{{.*}}[[USIZE:i[0-9]+]] @ptr_to_int({{i16\*|ptr}} noundef %p)
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// NOTE(eddyb) see above, the following two CHECK lines should ideally be this:
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// %2 = ptrtoint i16* %p to [[USIZE]]
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// store [[USIZE]] %2, [[USIZE]]* %0
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// CHECK: store {{i16\*|ptr}} %p, {{.*}}
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// CHECK-NEXT: %[[RES:.*]] = load [[USIZE]], {{.*}} %0
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// CHECK: ret [[USIZE]] %[[RES]]
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#[no_mangle]
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pub fn ptr_to_int(p: *mut u16) -> usize {
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unsafe { std::mem::transmute(p) }
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}
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// CHECK: define{{.*}}{{i16\*|ptr}} @int_to_ptr([[USIZE]] noundef %i)
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// NOTE(eddyb) see above, the following two CHECK lines should ideally be this:
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// %2 = inttoptr [[USIZE]] %i to i16*
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// store i16* %2, i16** %0
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// CHECK: store [[USIZE]] %i, {{.*}}
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// CHECK-NEXT: %[[RES:.*]] = load {{i16\*|ptr}}, {{.*}} %0
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// CHECK: ret {{i16\*|ptr}} %[[RES]]
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#[no_mangle]
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pub fn int_to_ptr(i: usize) -> *mut u16 {
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unsafe { std::mem::transmute(i) }
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}
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