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f6a57c1955
This approach depends on CSE to not have any branches or selects when the guessed offset is correct -- which it always will be right now -- but to also be *sound* (just less efficient) if the layout algorithms change such that the guess is incorrect.
37 lines
830 B
Rust
37 lines
830 B
Rust
// compile-flags: -O -Z randomize-layout=no
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// only-x86_64
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#![crate_type = "lib"]
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#![feature(option_as_slice)]
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extern crate core;
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use core::num::NonZeroU64;
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use core::option::Option;
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// CHECK-LABEL: @u64_opt_as_slice
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#[no_mangle]
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pub fn u64_opt_as_slice(o: &Option<u64>) -> &[u64] {
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// CHECK-NOT: select
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// CHECK-NOT: br
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// CHECK-NOT: switch
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// CHECK-NOT: icmp
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o.as_slice()
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}
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// CHECK-LABEL: @nonzero_u64_opt_as_slice
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#[no_mangle]
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pub fn nonzero_u64_opt_as_slice(o: &Option<NonZeroU64>) -> &[NonZeroU64] {
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// CHECK-NOT: select
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// CHECK-NOT: br
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// CHECK-NOT: switch
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// CHECK-NOT: icmp
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// CHECK: %[[NZ:.+]] = icmp ne i64 %{{.+}}, 0
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// CHECK-NEXT: zext i1 %[[NZ]] to i64
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// CHECK-NOT: select
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// CHECK-NOT: br
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// CHECK-NOT: switch
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// CHECK-NOT: icmp
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o.as_slice()
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}
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