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1. xalancbmk's bitset implementation has a redundant bit clear before setting the same bit.  This can be fixed in a generic way with an additional logical simplification pattern 
2. bext can be used to extract a single bit, storing the result into an SImode object, even for rv64 since bits 1..63 will be zero'd by the (&1) operation in the bext specification.
3. ~(1 << N) & C can be safely used for a 32bit object on rv64 when C has 33 or more leading zeros
4. (1 << N) | C and (1 << N) ^ C can be safely used when the logical XOR/IOR is done in DImode since we don't have to worry about sign-extending a DImode object
5. An explicit extension of SImode (1 << N) to DImode can be handled with a simple bset with x0 as a source operand
6. Occasionally GCC will use a "zero_extract" as a destination for some bifield insertions which can be handled with bset/bclr

Stakeholders/Partners

RISE:

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• (1 <<N) | C and (1 << N) ^ C for DImode objects has been integrated
• Explicit zero extension of (1 << N) in SImode  using bset has been submitted & integrated
• Handling of zero_extract destinations for single bit insertions has been submitted

10 Jun 2024 

• Raphael's code for using bext to extract a single bit, storing the result in an SImode object for rv64 has been integrated
• Raphael's code to handle ~(1 << N) & C where C has at least 33 leading zeros has been integrated
• Jeff's code to handle (1 << N) | C and (1 << N) ^ C for DImode objects has been submitted

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