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Auto merge of #81354 - SkiFire13:binary-search-assume, r=nagisa
Instruct LLVM that binary_search returns a valid index This allows removing bound checks when the return value of `binary_search` is used to index into the slice it was call on. I also added a codegen test for this, not sure if it's the right thing to do (I didn't find anything on the dev guide), but it felt so.
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// min-llvm-version: 11.0.0 | ||
// compile-flags: -O | ||
// ignore-debug: the debug assertions get in the way | ||
#![crate_type = "lib"] | ||
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// Make sure no bounds checks are emitted when slicing or indexing | ||
// with an index from `binary_search`. | ||
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// CHECK-LABEL: @binary_search_index_no_bounds_check | ||
#[no_mangle] | ||
pub fn binary_search_index_no_bounds_check(s: &[u8]) -> u8 { | ||
// CHECK-NOT: panic | ||
// CHECK-NOT: slice_index_len_fail | ||
if let Ok(idx) = s.binary_search(&b'\\') { | ||
s[idx] | ||
} else { | ||
42 | ||
This comment has been minimized.
Sorry, something went wrong. |
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} | ||
} |
what does this 42 mean?