[Bug target/120333] [16 Regression] RISC-V: Wrong code with bitmanip extension
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120333 Jeffrey A. Law changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #4 from Jeffrey A. Law --- Fixed on the trunk.
[Bug target/120333] [16 Regression] RISC-V: Wrong code with bitmanip extension
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120333 --- Comment #3 from GCC Commits --- The master branch has been updated by Jeff Law : https://gcc.gnu.org/g:38fa6c0455ec14f2f42310a817b90765ad894aa4 commit r16-740-g38fa6c0455ec14f2f42310a817b90765ad894aa4 Author: Jeff Law Date: Mon May 19 16:55:15 2025 -0600 [committed][RISC-V][PR target/120333] Remove bogus bext pattern I goof'd when doing analysis of missed bext cases. For the shift into the sign bit, then shift into the low bit case (thankfully the least common), I got it in my brain that the field is at the left shift count. It's actually at word_size - 1 - left shift count. One the subtraction is included, it's no longer profitable to turn those cases into bext. Best case scenario would be sub+bext, but we can just as easily use sll+srl which fuses in some designs into a single op. So this patch removes those two patterns, adjusts the existing testcase and adds the new execution test. Given it's a partial reversion and has passed in my tester, I'm going to go ahead and push it to the trunk rather than waiting for upstream CI. PR target/120333 gcc/ * config/riscv/bitmanip.md: Remove bext formed from left+right shift patterns. gcc/testsuite/ * gcc.target/riscv/pr114512.c: Update expected output. * gcc.target/riscv/pr120333.c: New test.
[Bug target/120333] [16 Regression] RISC-V: Wrong code with bitmanip extension
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120333 Jeffrey A. Law changed: What|Removed |Added Status|NEW |ASSIGNED --- Comment #2 from Jeffrey A. Law --- I think the pattern in that change is just bogus. I forgot to account for the fact that the left shift value isn't the bit position we care about. The position we care about is 63/31 - shift value (rv64/rv32). Once we take into the account the need for that adjustment, the new code is no better than the old code. Thankfully that variant is the least important of the single bit extraction variants.
[Bug target/120333] [16 Regression] RISC-V: Wrong code with bitmanip extension
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120333 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |NEW Ever confirmed|0 |1 Last reconfirmed||2025-05-18 See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=114512 --- Comment #1 from Andrew Pinski --- Confirmed. Looks like it might be caused by r16-411-g4cd741dcbd3729 .
[Bug target/120333] [16 Regression] RISC-V: Wrong code with bitmanip extension
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120333 Andrew Pinski changed: What|Removed |Added Target Milestone|--- |16.0 Summary|RISC-V: Wrong code with |[16 Regression] RISC-V: |bitmanip extension |Wrong code with bitmanip ||extension
