search for: constanttime

...Carry-less_product">https://en.wikipedia.org/wiki/Carry-less_product</a><br /><a href="https://en.wikipedia.org/wiki/Carry-less_product%5B2%5D%20(page%2030)%20https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf%5B3%5D%20https://www.bearssl.org/constanttime.html">[2] (page 30) </a><a href="https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf">https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf</a><br /><a href="https://en.wikipedia.org/wiki/Carry-l...

...120, or if bitreverse is available 16x16=>32 to TWO 64x64=>64 multiplications)[3]. >> >> [1] https://en.wikipedia.org/wiki/Carry-less_product >> [2] (page 30) https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf >> [3] https://www.bearssl.org/constanttime.html > > What benefit would this intrinsic would bring to the middle-end IR, > over it's current naive expanded form? Isn't a "naive" expansion of NxN carryless multiply extremely involved? I'd expect something like 2N shifts, N truncs, N selects, and N xors. That...

..., or if bitreverse is available 16x16=>32 to TWO 64x64=>64 multiplications)[3]. >> >>  [1] https://en.wikipedia.org/wiki/Carry-less_product >>  [2] (page 30) https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf >>  [3] https://www.bearssl.org/constanttime.html > > What benefit would this intrinsic would bring to the middle-end IR, > over it's current naive expanded form? > > Note that teaching backends to produce it, or even adding it to > backend (ISD opcodes) > and matching it in DAGCombiner has much lower barrier of entry...

...to a 60x60=>120, or if bitreverse is available 16x16=>32 to TWO 64x64=>64 multiplications)[3]. > > [1] https://en.wikipedia.org/wiki/Carry-less_product > [2] (page 30) https://raw.githubusercontent.com/riscv/riscv-bitmanip/master/bitmanip-0.92.pdf > [3] https://www.bearssl.org/constanttime.html > > > > (First posted to discord > > -- > Shawn Landden > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > ________________...