| Summary: | MVE: Invalid addressing mode generated for VLD2 | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Kevin Bracey <kevin.bracey> |
| Component: | target | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | stammark |
| Priority: | P3 | Keywords: | wrong-code |
| Version: | 13.0 | ||
| Target Milestone: | --- | ||
| Host: | Target: | arm | |
| Build: | Known to work: | ||
| Known to fail: | 11.3.1, 12.2.1 | Last reconfirmed: | 2022-12-09 00:00:00 |
| Attachments: | Stripped-down reproducer source | ||
|
Description
Kevin Bracey
2022-11-16 12:56:04 UTC
Looking at that assembly output from Compiler Explorer, I'm also at a loss as to what happened to the "6" for the VMUL. Maybe something else to look at? Ah, the vmulq is falling foul of some sort of generic selection problem. Substituting with vmulq_n_u8() gets me the actual 6. Something in the same area as my bug 107515, perhaps - I've been making liberal use of the generic functions. Thanks for finding this! Confirmed the `vld2` bug on latest trunk -- my guess would be either a GCC backend or a gas bug (I'm not familiar with these instructions). For the `vmulq` issue I'll reply under the other thread, but I believe that very soon we'll be able to put that down as "already fixed", so we can keep this thread for `vld2` only. The assembler's rejection of the vld2 is valid - the only permitted post-indexed form is to use "!" for increment by 32 (the amount read). Experimenting by changing "inStep" you can see the compiler backend knows that 32 is the only valid constant offset - it generates the "!" form for that correctly - but it apparently hasn't been told not to use register offsets. I had a look at the GCC source. The vld2/vst2/vld4/vst4 instructions in mve.md have reused the "Um" constraint used for vld<N>/vst<N> in Neon, which permits both "!" and register offset. This needs to be tightened up - can't see an existing equivalent constraint. Perhaps "Um" can be given variant MVE/Neon behaviour, like "Uj". The master branch has been updated by Stam Markianos-Wright <stammark@gcc.gnu.org>: https://gcc.gnu.org/g:4269a6567eb991e6838f40bda5be9e3a7972530c commit r13-4935-g4269a6567eb991e6838f40bda5be9e3a7972530c Author: Stam Markianos-Wright <stam.markianos-wright@arm.com> Date: Fri Dec 30 11:25:22 2022 +0000 Fix memory constraint on MVE v[ld/st][2/4] instructions [PR107714] In the M-Class Arm-ARM: https://developer.arm.com/documentation/ddi0553/bu/?lang=en these MVE instructions only have '!' writeback variant and at: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107714 we found that the Um constraint would also allow through a register offset writeback, resulting in an assembler error. Here I have added a new constraint and predicate for these instructions, which (uniquely, AFAICT), only support a `!` writeback increment by the data size (inside the compiler this is a POST_INC). No regressions in arm-none-eabi with MVE and MVE.FP. gcc/ChangeLog: PR target/107714 * config/arm/arm-protos.h (mve_struct_mem_operand): New protoype. * config/arm/arm.cc (mve_struct_mem_operand): New function. * config/arm/constraints.md (Ug): New constraint. * config/arm/mve.md (mve_vst4q<mode>): Change constraint. (mve_vst2q<mode>): Likewise. (mve_vld4q<mode>): Likewise. (mve_vld2q<mode>): Likewise. * config/arm/predicates.md (mve_struct_operand): New predicate. gcc/testsuite/ChangeLog: PR target/107714 * gcc.target/arm/mve/intrinsics/vldst24q_reg_offset.c: New test. The releases/gcc-11 branch has been updated by Stam Markianos-Wright <stammark@gcc.gnu.org>: https://gcc.gnu.org/g:08842ad274f5e2630994f7c6e70b2d31768107ea commit r11-10461-g08842ad274f5e2630994f7c6e70b2d31768107ea Author: Stam Markianos-Wright <stam.markianos-wright@arm.com> Date: Fri Dec 30 11:25:22 2022 +0000 Fix memory constraint on MVE v[ld/st][2/4] instructions [PR107714] In the M-Class Arm-ARM: https://developer.arm.com/documentation/ddi0553/bu/?lang=en these MVE instructions only have '!' writeback variant and at: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107714 we found that the Um constraint would also allow through a register offset writeback, resulting in an assembler error. Here I have added a new constraint and predicate for these instructions, which (uniquely, AFAICT), only support a `!` writeback increment by the data size (inside the compiler this is a POST_INC). No regressions in arm-none-eabi with MVE and MVE.FP. gcc/ChangeLog: PR target/107714 * config/arm/arm-protos.h (mve_struct_mem_operand): New protoype. * config/arm/arm.c (mve_struct_mem_operand): New function. * config/arm/constraints.md (Ug): New constraint. * config/arm/mve.md (mve_vst4q<mode>): Change constraint. (mve_vst2q<mode>): Likewise. (mve_vld4q<mode>): Likewise. (mve_vld2q<mode>): Likewise. * config/arm/predicates.md (mve_struct_operand): New predicate. gcc/testsuite/ChangeLog: PR target/107714 * gcc.target/arm/mve/intrinsics/vldst24q_reg_offset.c: New test. (cherry picked from commit 4269a6567eb991e6838f40bda5be9e3a7972530c) The releases/gcc-12 branch has been updated by Stam Markianos-Wright <stammark@gcc.gnu.org>: https://gcc.gnu.org/g:25edc76f2afba0b4eaf22174d42de042a6969dbe commit r12-9038-g25edc76f2afba0b4eaf22174d42de042a6969dbe Author: Stam Markianos-Wright <stam.markianos-wright@arm.com> Date: Fri Dec 30 11:25:22 2022 +0000 Fix memory constraint on MVE v[ld/st][2/4] instructions [PR107714] In the M-Class Arm-ARM: https://developer.arm.com/documentation/ddi0553/bu/?lang=en these MVE instructions only have '!' writeback variant and at: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107714 we found that the Um constraint would also allow through a register offset writeback, resulting in an assembler error. Here I have added a new constraint and predicate for these instructions, which (uniquely, AFAICT), only support a `!` writeback increment by the data size (inside the compiler this is a POST_INC). No regressions in arm-none-eabi with MVE and MVE.FP. gcc/ChangeLog: PR target/107714 * config/arm/arm-protos.h (mve_struct_mem_operand): New protoype. * config/arm/arm.cc (mve_struct_mem_operand): New function. * config/arm/constraints.md (Ug): New constraint. * config/arm/mve.md (mve_vst4q<mode>): Change constraint. (mve_vst2q<mode>): Likewise. (mve_vld4q<mode>): Likewise. (mve_vld2q<mode>): Likewise. * config/arm/predicates.md (mve_struct_operand): New predicate. gcc/testsuite/ChangeLog: PR target/107714 * gcc.target/arm/mve/intrinsics/vldst24q_reg_offset.c: New test. (cherry picked from commit 4269a6567eb991e6838f40bda5be9e3a7972530c) This should now be resolved on all active branches (11, 12, 13) |