On 11/8/22 12:56, Philipp Tomsich wrote:
When using strength-reduction, we will reduce a multiplication to a
sequence of shifts and adds. If this is performed with 32-bit types
and followed by a division, the lack of w-form sh[123]add will make
combination impossible and lead to a slli + addw being generated.
Split the sequence with the knowledge that a w-form div will perform
implicit sign-extensions.
gcc/ChangeLog:
* config/riscv/bitmanip.md: Add a define_split to optimize
slliw + addiw + divw into sh[123]add + divw.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/zba-shNadd-05.c: New test.
OK. I won't complain about the subregs on this one :-)
jeff
