On Sat, Jun 10, 2023 at 7:53 PM Jeff Law <jeffreya...@gmail.com> wrote: > > > > On 4/28/23 00:23, Christoph Muellner wrote: > > From: Christoph Müllner <christoph.muell...@vrull.eu> > > > > The XTheadMemIdx ISA extension provides a additional load and store > > instructions with new addressing modes. > > > > The following memory accesses types are supported: > > * ltype = [b,bu,h,hu,w,wu,d] > > * stype = [b,h,w,d] > > > > The following addressing modes are supported: > > * immediate offset with PRE_MODIFY or POST_MODIFY (22 instructions): > > l<ltype>.ia, l<ltype>.ib, s<stype>.ia, s<stype>.ib > > * register offset with additional immediate offset (11 instructions): > > lr<ltype>, sr<stype> > > * zero-extended register offset with additional immediate offset > > (11 instructions): lur<ltype>, sur<stype> > > > > The RISC-V base ISA does not support index registers, so the changes > > are kept separate from the RISC-V standard support. > > > > Similar like other extensions (Zbb, XTheadBb), this patch needs to > > prevent the conversion of sign-extensions/zero-extensions into > > shift instructions. The case of the zero-extended register offset > > addressing mode is handled by a new peephole pass. > > > > Handling the different cases of extensions results in a couple of INSNs > > that look redundant on first view, but they are just the equivalent > > of what we already have for Zbb as well. The only difference is, that > > we have much more load instructions. > > > > To fully utilize the capabilities of the instructions, there are > > a few new peephole passes which fold shift amounts into the RTX > > if possible. The added tests ensure that this feature won't > > regress without notice. > > > > We already have a constraint with the name 'th_f_fmv', therefore, > > the new constraints follow this pattern and have the same length > > as required ('th_m_mia', 'th_m_mib', 'th_m_mir', 'th_m_miu'). > > > > gcc/ChangeLog: > > > > * config/riscv/constraints.md (th_m_mia): New constraint. > > (th_m_mib): Likewise. > > (th_m_mir): Likewise. > > (th_m_miu): Likewise. > > * config/riscv/riscv-protos.h (enum riscv_address_type): > > Add new address types ADDRESS_REG_REG, ADDRESS_REG_UREG, > > and ADDRESS_REG_WB and their documentation. > > (struct riscv_address_info): Add new field 'shift' and > > document the field usage for the new address types. > > (riscv_valid_base_register_p): New prototype. > > (th_memidx_legitimate_modify_p): Likewise. > > (th_memidx_legitimate_index_p): Likewise. > > (th_classify_address): Likewise. > > (th_output_move): Likewise. > > (th_print_operand_address): Likewise. > > * config/riscv/riscv.cc (riscv_index_reg_class): > > Return GR_REGS for XTheadMemIdx. > > (riscv_regno_ok_for_index_p): Add support for XTheadMemIdx. > > (riscv_classify_address): Call th_classify_address() on top. > > (riscv_output_move): Call th_output_move() on top. > > (riscv_print_operand_address): Call th_print_operand_address() > > on top. > > * config/riscv/riscv.h (HAVE_POST_MODIFY_DISP): New macro. > > (HAVE_PRE_MODIFY_DISP): Likewise. > > * config/riscv/riscv.md (zero_extendqi<SUPERQI:mode>2): Disable > > for XTheadMemIdx. > > (*zero_extendqi<SUPERQI:mode>2_internal): Convert to expand, > > create INSN with same name and disable it for XTheadMemIdx. > > (extendsidi2): Likewise. > > (*extendsidi2_internal): Disable for XTheadMemIdx. > > * config/riscv/thead-peephole.md: Add helper peephole passes. > > * config/riscv/thead.cc (valid_signed_immediate): New helper > > function. > > (th_memidx_classify_address_modify): New function. > > (th_memidx_legitimate_modify_p): Likewise. > > (th_memidx_output_modify): Likewise. > > (is_memidx_mode): Likewise. > > (th_memidx_classify_address_index): Likewise. > > (th_memidx_legitimate_index_p): Likewise. > > (th_memidx_output_index): Likewise. > > (th_classify_address): Likewise. > > (th_output_move): Likewise. > > (th_print_operand_address): Likewise. > > * config/riscv/thead.md (*th_memidx_mov<mode>2): > > New INSN. > > (*th_memidx_zero_extendqi<SUPERQI:mode>2): Likewise. > > (*th_memidx_extendsidi2): Likewise > > (*th_memidx_zero_extendsidi2): Likewise. > > (*th_memidx_zero_extendhi<GPR:mode>2): Likewise. > > (*th_memidx_extend<SHORT:mode><SUPERQI:mode>2): Likewise > > (*th_memidx_bb_zero_extendsidi2): Likewise. > > (*th_memidx_bb_zero_extendhi<GPR:mode>2): Likewise. > > (*th_memidx_bb_extendhi<GPR:mode>2): Likewise. > > (*th_memidx_bb_extendqi<SUPERQI:mode>2): Likewise. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.target/riscv/xtheadmemidx-helpers.h: New test. > > * gcc.target/riscv/xtheadmemidx-index-update.c: New test. > > * gcc.target/riscv/xtheadmemidx-index-xtheadbb-update.c: New test. > > * gcc.target/riscv/xtheadmemidx-index-xtheadbb.c: New test. > > * gcc.target/riscv/xtheadmemidx-index.c: New test. > > * gcc.target/riscv/xtheadmemidx-modify-xtheadbb.c: New test. > > * gcc.target/riscv/xtheadmemidx-modify.c: New test. > > * gcc.target/riscv/xtheadmemidx-uindex-update.c: New test. > > * gcc.target/riscv/xtheadmemidx-uindex-xtheadbb-update.c: New test. > > * gcc.target/riscv/xtheadmemidx-uindex-xtheadbb.c: New test. > > * gcc.target/riscv/xtheadmemidx-uindex.c: New test. > > > > > > > diff --git a/gcc/config/riscv/thead-peephole.md > > b/gcc/config/riscv/thead-peephole.md > > index 5b829b5b968..2a4c734a220 100644 > > --- a/gcc/config/riscv/thead-peephole.md > > +++ b/gcc/config/riscv/thead-peephole.md > > @@ -72,3 +72,217 @@ (define_peephole2 > > { > > th_mempair_order_operands (operands, true, SImode); > > }) > > + > > +;; All modes that are supported by XTheadMemIdx > > +(define_mode_iterator TH_M_ANY [QI HI SI (DI "TARGET_64BIT")]) > > + > > +;; All non-extension modes that are supported by XTheadMemIdx > > +(define_mode_iterator TH_M_NOEXT [(SI "!TARGET_64BIT") (DI > > "TARGET_64BIT")]) > > + > > +;; XTheadMemIdx overview: > > +;; All peephole passes attempt to improve the operand utilization of > > +;; XTheadMemIdx instructions, where one sign or zero extended > > +;; register-index-operand can be shifted left by a 2-bit immediate. > > +;; > > +;; The basic idea is the following optimization: > > +;; (set (reg 0) (op (reg 1) (imm 2))) > > +;; (set (reg 3) (mem (plus (reg 0) (reg 4))) > > +;; ==> > > +;; (set (reg 3) (mem (plus (reg 4) (op2 (reg 1) (imm 2)))) > > +;; This optimization only valid if (reg 0) has no further uses. > Couldn't this be done by combine if you created define_insn patterns > rather than define_peephole2 patterns? Similarly for the other cases > handled here.
I was inspired by XTheadMemPair, which merges two memory accesses into a mem-pair instruction (and which got inspiration from gcc/config/aarch64/aarch64-ldpstp.md). I don't see the benefit of using combine or peephole, but I can change if necessary. At least for the provided test cases, the implementation works quite well. > > Do you need to define HAVE_{PRE,POST}_MODIFY? I see > HAVE_{PRE,POST}_MODIFY_DISP. is defined. If that's sufficient, great. > This stuff seems to have changed since I last looked at it. There is no HAVE_{PRE,POST}_MODIFY, only HAVE_{PRE,POST}_MODIFY_REG (register) and HAVE_{PRE,POST}_MODIFY_DISP (constant displacement). The defined macros are matching the expectation of gcc/auto-inc-dec.cc and also match the documentation. > So I have to ask. Is the extension documented? If so, we probably > should have a link to it. What's the status of hardware availablity > with this extension? The basic support for this extension is already merged. The documentation can be found here: https://github.com/T-head-Semi/thead-extension-spec/tree/master The extension's name and a link to the documentation has also been registered here: https://github.com/riscv-non-isa/riscv-toolchain-conventions#list-of-vendor-extensions The XTheadMemIdx extension is part of the T-Head C906 and C910 SoCs. The C906 was launched in October 2021. Thanks Christoph