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Update rustc_codegen_gcc rotate operation document #145278

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Update rustc_codegen_gcc rotate operation document #145278

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5 changes: 3 additions & 2 deletions compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -493,9 +493,10 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tc
}
sym::bitreverse => self.bit_reverse(width, args[0].immediate()),
sym::rotate_left | sym::rotate_right => {
// TODO(antoyo): implement using algorithm from:
// Using optimized branchless algorithm from:
// https://blog.regehr.org/archives/1063
// for other platforms.
// This implementation uses the pattern (x<<n) | (x>>(-n&(width-1)))
// which generates efficient code for other platforms.
let is_left = name == sym::rotate_left;
let val = args[0].immediate();
let raw_shift = args[1].immediate();
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