On Thu, Jul 3, 2025 at 4:50 AM Richard Sandiford <richard.sandif...@arm.com> wrote: > > Karl Meakin <karl.mea...@arm.com> writes: > > This patch series adds support for the CMPBR extension. It includes the > > new `+cmpbr` option and rules to generate the new instructions when > > lowering conditional branches. > > Thanks for the update, LGTM. I've pushed the series to trunk.
So cmpbr is broken in one case dealing with `(lt reg:DI (const_int 0))` due to matching aarch64_tbzltdi1 when if there is a possibility of adding clobbers and aarch64_cbltdi otherwise. I can see two ways of fixing this, move the `aarch64_cb*` patterns before the `aarch64_tbzlt` pattern then aarch64_cbltdi will no matter if there is a possibility of adding clobbers. The other way is to disable `aarch64_tbzlt` patterns for TARGET_CMPBR. Which one do you prefer? Note this is https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121385 which shows up building libgcc with CMPBR enabled. Thanks, Andrew > > Richard > > > Changelog: > > * v9: > > - Mark the non-far branches unlikely, so that the branch is consistently > > generated as: > > ```asm > > branch-if-true .L123 > > b not_taken > > .L123: > > b taken > > ``` > > * v8: > > - Support far branches for the `CBB` and `CBH` instructions, and add > > tests for them. > > - Mark the branch in the far branch tests likely, so that the optimizer > > does > > not invert the condition. > > - Use regex captures for register and label names so that the tests are > > less fragile. > > - Minor formatting fixes. > > * v7: > > - Support far branches and add a test for them. > > - Replace `aarch64_cb_short_operand` with `aarch64_reg_or_zero_operand`. > > - Delete the new predicates that aren't needed anymore. > > - Minor formatting and comment fixes. > > * v6: > > - Correct the constraint string for immediate operands. > > - Drop the commit for adding `%j` format specifiers. The suffix for > > the `cb` instruction is now calculated by the `cmp_op` code > > attribute. > > * v5: > > - Moved Moved patch 10/10 (adding %j ...) before patch 8/10 (rules for > > CMPBR...). Every commit in the series should now produce a correct > > compiler. > > - Reduce excessive diff context by not passing `--function-context` to > > `git format-patch`. > > * v4: > > - Added a commit to use HS/LO instead of CS/CC mnemonics. > > - Rewrite the range checks for immediate RHSes in aarch64.cc: CBGE, > > CBHS, CBLE and CBLS have different ranges of allowed immediates than > > the other comparisons. > > > > Karl Meakin (9): > > AArch64: place branch instruction rules together > > AArch64: reformat branch instruction rules > > AArch64: rename branch instruction rules > > AArch64: add constants for branch displacements > > AArch64: make `far_branch` attribute a boolean > > AArch64: recognize `+cmpbr` option > > AArch64: precommit test for CMPBR instructions > > AArch64: rules for CMPBR instructions > > AArch64: make rules for CBZ/TBZ higher priority > > > > .../aarch64/aarch64-option-extensions.def | 2 + > > gcc/config/aarch64/aarch64-protos.h | 2 + > > gcc/config/aarch64/aarch64-simd.md | 2 +- > > gcc/config/aarch64/aarch64-sme.md | 2 +- > > gcc/config/aarch64/aarch64.cc | 39 +- > > gcc/config/aarch64/aarch64.h | 3 + > > gcc/config/aarch64/aarch64.md | 570 ++++-- > > gcc/config/aarch64/constraints.md | 18 + > > gcc/config/aarch64/iterators.md | 30 + > > gcc/doc/invoke.texi | 3 + > > gcc/testsuite/gcc.target/aarch64/cmpbr.c | 1824 +++++++++++++++++ > > gcc/testsuite/lib/target-supports.exp | 14 +- > > 12 files changed, 2285 insertions(+), 224 deletions(-) > > create mode 100644 gcc/testsuite/gcc.target/aarch64/cmpbr.c > > > > -- > > 2.48.1
