This pseudo-instruction is similar to la but uses PC-relative addressing
unconditionally. This is, la is only different to lla when using -fPIC. This
pseudo-instruction seems often forgotten in several specs but it is definitely
mentioned in binutils opcodes/riscv-opc.c. The semantics are defined both in
page 37 of the "RISC-V Reader" book but also in function macro found in
gas/config/tc-riscv.c.
This is a very first step towards adding PIC support for Linux in the RISC-V
backend.
The lla pseudo-instruction expands to a sequence of auipc + addi with a couple
of pc-rel relocations where the second points to the first one. This is
described in
https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#pc-relative-symbol-addresses
For now, this patch only introduces support of that pseudo instruction at the
assembler parser.
Differential Revision: https://reviews.llvm.org/D49661
llvm-svn: 339314
Match the GNU assembler in supporting immediate operands for these
instructions even when the reg-reg mnemonic is used.
Differential Revision: https://reviews.llvm.org/D50046
Patch by Kito Cheng.
llvm-svn: 339252
Summary:
When expanding the PseudoTail in expandFunctionCall() we were using X6
to save the return address. Since this is a tail call the return
address is not needed, this patch replaces it with X0 to be ignored.
This matches the behaviour listed in the ISA V2.2 document page 110.
tail offset -----> jalr x0, x6, offset
GCC exhibits the same behavior.
Reviewers: apazos, asb, mgrang
Reviewed By: asb
Subscribers: rbar, johnrusso, simoncook, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01
Differential Revision: https://reviews.llvm.org/D48343
llvm-svn: 335239
These instructions were renamed in version 2.2 of the user-level ISA spec, but
the old name should also be accepted by standard tools.
llvm-svn: 335154
These are produced by GCC and supported by GAS, but not currently contained in
the pseudoinstruction listing in the RISC-V ISA manual.
llvm-svn: 335127
These are produced by GCC and supported by GAS, but not currently contained in
the pseudoinstruction listing in the RISC-V ISA manual.
llvm-svn: 335120
The instruction makes use of a previously ignored field in the fence
instruction. It is introduced in the version 2.3 draft of the RISC-V
specification after much work by the Memory Model Task Group.
As clarified here <https://github.com/riscv/riscv-isa-manual/issues/186>,
the fence.tso assembler mnemonic does not have operands.
llvm-svn: 334278
The implementation follows the MIPS backend and expands the pseudo instruction
directly during asm parsing. As the result, only real MC instructions are
emitted to the MCStreamer. The actual expansion to real instructions is
similar to the expansion performed by the GNU Assembler.
This patch supersedes D41949.
Differential Revision: https://reviews.llvm.org/D46118
Patch by Mario Werner.
llvm-svn: 334203
Resolving fixup_riscv_call by assembler when the linker relaxation diabled
and the function and callsite within the same compile unit.
And also adding static_assert after Infos array declaration
to avoid missing any new fixup in MCFixupKindInfo in the future.
Differential Revision: https://reviews.llvm.org/D47126
llvm-svn: 333487
To do this:
1. Add fixup_riscv_relax fixup types which eventually will
transfer to R_RISCV_RELAX relocation types.
2. Insert R_RISCV_RELAX relocation types to auipc function call
expression when linker relaxation enabled.
Differential Revision: https://reviews.llvm.org/D44886
llvm-svn: 333158
For RISC-V it is desirable to have relaxation happen in the linker once
addresses are known, and as such the size between two instructions/byte
sequences in a section could change.
For most assembler expressions, this is fine, as the absolute address results
in the expression being converted to a fixup, and finally relocations.
However, for expressions such as .quad .L2-.L1, the assembler folds this down
to a constant once fragments are laid out, under the assumption that the
difference can no longer change, although in the case of linker relaxation the
differences can change at link time, so the constant is incorrect. One place
where this commonly appears is in debug information, where the size of a
function expression is in a form similar to the above.
This patch extends the assembler to allow an AsmBackend to declare that it
does not want the assembler to fold down this expression, and instead generate
a pair of relocations that allow the linker to carry out the calculation. In
this case, the expression is not folded, but when it comes to emitting a
fixup, the generic FK_Data_* fixups are converted into a pair, one for the
addition half, one for the subtraction, and this is passed to the relocation
generating methods as usual. I have named these FK_Data_Add_* and
FK_Data_Sub_* to indicate which half these are for.
For RISC-V, which supports this via e.g. the R_RISCV_ADD64, R_RISCV_SUB64 pair
of relocations, these are also set to always emit relocations relative to
local symbols rather than section offsets. This is to deal with the fact that
if relocations were calculated on e.g. .text+8 and .text+4, the result 12
would be stored rather than 4 as both addends are added in the linker.
Differential Revision: https://reviews.llvm.org/D45181
Patch by Simon Cook.
llvm-svn: 333079
For RISCV branch instructions, we need to preserve relocation types when linker
relaxation enabled, so then linker could modify offset when the branch offsets
changed.
We preserve relocation types by define shouldForceRelocation.
IsResolved return by evaluateFixup will always false when shouldForceRelocation
return true. It will make RISCV MC Branch Relaxation always relax 16-bit
branches to 32-bit form, even if the symbol actually could be resolved.
To avoid 16-bit branches always relax to 32-bit form when linker relaxation
enabled, we add a new parameter WasForced to indicate that the symbol actually
couldn't be resolved and not forced by shouldForceRelocation return true.
RISCVAsmBackend::fixupNeedsRelaxationAdvanced could relax branches with
unresolved symbols by (!IsResolved && !WasForced).
RISCV MC Branch Relaxation is needed because RISCV could perform 32-bit
to 16-bit transformation in MC layer.
Differential Revision: https://reviews.llvm.org/D46350
llvm-svn: 332696
Summary:
This patch implements MC support for tail psuedo instruction.
A follow-up patch implements the codegen support as well as handling of the indirect tail pseudo instruction.
Reviewers: asb, apazos
Reviewed By: asb
Subscribers: rbar, johnrusso, simoncook, jordy.potman.lists, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, llvm-commits
Differential Revision: https://reviews.llvm.org/D46221
llvm-svn: 332634
These directives are recognised by gas. Support is added through the use of
addAliasForDirective.
Also match RISC-V gcc in preferring .half and .word for 16-bit and 32-bit data
directives.
llvm-svn: 332574
These directives allow the 'C' (compressed) extension to be enabled/disabled
within a single file.
Differential Revision: https://reviews.llvm.org/D45864
Patch by Kito Cheng
llvm-svn: 332107
Previously `call zero`, `call f0` etc would fail. This leads to compilation
failures if building programs that define functions with those names and using
-save-temps.
llvm-svn: 330846
To do this:
1. Add PseudoCALLIndirct to match indirect function call.
2. Add PseudoCALL to support parsing and print pseudo `call` in assembly
3. Expand PseudoCALL to the following form with R_RISCV_CALL relocation type
while encoding:
auipc ra, func
jalr ra, ra, 0
If we expand PseudoCALL before emitting assembly, we will see auipc and jalr
pair when compile with -S. It's hard for assembly parser to parsing this
pair and identify it's semantic is function call and then insert R_RISCV_CALL
relocation type. Although we could insert R_RISCV_PCREL_HI20 and
R_RISCV_PCREL_LO12_I relocation types instead of R_RISCV_CALL.
Due to RISCV relocation design, auipc and jalr pair only can relax to jal with
R_RISCV_CALL + R_RISCV_RELAX relocation types.
We expand PseudoCALL as late as encoding(RISCVMCCodeEmitter) instead of before
emitting assembly(RISCVAsmPrinter) because we want to preserve call
pseudoinstruction in assembly code. It's more readable and assembly parser
could identify call assembly and insert R_RISCV_CALL relocation type.
Differential Revision: https://reviews.llvm.org/D45859
llvm-svn: 330826
Reverts rL330224, while issues with the C extension and missed common
subexpression elimination opportunities are addressed. Neither of these issues
are visible in current RISC-V backend unit tests, which clearly need
expanding.
llvm-svn: 330281
The implementation follows the MIPS backend and expands the
pseudo instruction directly during asm parsing. As the result, only
real MC instructions are emitted to the MCStreamer. Additionally,
PseudoLI instructions are emitted during codegen. The actual
expansion to real instructions is performed during MI to MC lowering
and is similar to the expansion performed by the GNU Assembler.
Differential Revision: https://reviews.llvm.org/D41949
Patch by Mario Werner.
llvm-svn: 330224
Summary:
GCC compresses the pseudo instruction "mv rd, rs", which is an alias of
"addi rd, rs, 0", to "c.mv rd, rs".
In LLVM we rely on the canonical MC instruction (MCInst) to do our compression
checks and since there is no rule to compress "addi rd, rs, 0" --> "c.mv
rd, rs" we lose this compression opportunity to gcc.
In this patch we fix that by adding an addi to c.mv compression pattern, the
instruction "mv rd, rs" will be compressed to "c.mv rd, rs" just like
gcc does.
Patch by Zhaoshi Zheng (zzheng) and Sameer (sabuasal).
Reviewers: asb, apazos, zzheng, mgrang, shiva0217
Reviewed By: asb
Subscribers: rbar, johnrusso, simoncook, jordy.potman.lists, niosHD, kito-cheng, llvm-commits
Differential Revision: https://reviews.llvm.org/D45583
llvm-svn: 329939
Summary:
This patch implements a tablegen-driven Instruction Compression
mechanism for generating RISCV compressed instructions
(C Extension) from the expanded instruction form.
This tablegen backend processes CompressPat declarations in a
td file and generates all the compile-time and runtime checks
required to validate the declarations, validate the input
operands and generate correct instructions.
The checks include validating register operands, immediate
operands, fixed register operands and fixed immediate operands.
Example:
class CompressPat<dag input, dag output> {
dag Input = input;
dag Output = output;
list<Predicate> Predicates = [];
}
let Predicates = [HasStdExtC] in {
def : CompressPat<(ADD GPRNoX0:$rs1, GPRNoX0:$rs1, GPRNoX0:$rs2),
(C_ADD GPRNoX0:$rs1, GPRNoX0:$rs2)>;
}
The result is an auto-generated header file
'RISCVGenCompressEmitter.inc' which exports two functions for
compressing/uncompressing MCInst instructions, plus
some helper functions:
bool compressInst(MCInst& OutInst, const MCInst &MI,
const MCSubtargetInfo &STI,
MCContext &Context);
bool uncompressInst(MCInst& OutInst, const MCInst &MI,
const MCRegisterInfo &MRI,
const MCSubtargetInfo &STI);
The clients that include this auto-generated header file and
invoke these functions can compress an instruction before emitting
it, in the target-specific ASM or ELF streamer, or can uncompress
an instruction before printing it, when the expanded instruction
format aliases is favored.
The following clients were added to implement compression\uncompression
for RISCV:
1) RISCVAsmParser::MatchAndEmitInstruction:
Inserted a call to compressInst() to compresses instructions
parsed by llvm-mc coming from an ASM input.
2) RISCVAsmPrinter::EmitInstruction:
Inserted a call to compressInst() to compress instructions that
were lowered from Machine Instructions (MachineInstr).
3) RVInstPrinter::printInst:
Inserted a call to uncompressInst() to print the expanded
version of the instruction instead of the compressed one (e.g,
add s0, s0, a5 instead of c.add s0, a5) when -riscv-no-aliases
is not passed.
This patch squashes D45119, D42780 and D41932. It was reviewed in smaller patches by
asb, efriedma, apazos and mgrang.
Reviewers: asb, efriedma, apazos, llvm-commits, sabuasal
Reviewed By: sabuasal
Subscribers: mgorny, eraman, asb, rbar, johnrusso, simoncook, jordy.potman.lists, apazos, niosHD, kito-cheng, shiva0217, zzheng
Differential Revision: https://reviews.llvm.org/D45385
llvm-svn: 329455
Summary:
This patch updates MC tests related to compression in RISCV to
insure they work correctly with automatic compression and relaxation
enabled. This is the first part of a series of patches to implement
automatic compression for RISCV.
Reviewers: asb, apazos
Reviewed By: asb
Subscribers: shiva0217, efriedma, llvm-commits, asb, rbar, johnrusso, simoncook, jordy.potman.lists, apazos, niosHD, kito-cheng
Differential Revision: https://reviews.llvm.org/D43328
llvm-svn: 329441
Summary:
This patch implements relaxation for RISCV in the MC layer.
The following relaxations are currently handled:
1) Relax C_BEQZ to BEQ and C_BNEZ to BNEZ in RISCV.
2) Relax and C_J $imm to JAL x0, $imm and CJAL to JAL ra, $imm.
Reviewers: asb, llvm-commits, efriedma
Reviewed By: asb
Subscribers: shiva0217
Differential Revision: https://reviews.llvm.org/D43055
llvm-svn: 326626
Implement c.lui immediate constraint to [1, 31] and [0xfffe0, 0xfffff].
The RISC-V ISA describes the constraint as [1, 63], with that value
being loaded in to bits 17-12 of the destination register and sign extended
from bit 17. Therefore, this 6-bit immediate can represent values in the
ranges [1, 31] and [0xfffe0, 0xfffff].
Differential Revision: https://reviews.llvm.org/D42834
llvm-svn: 325792
llvm-objdump could get C feature by ELF::EF_RISCV_RVC e_flag,
so then we don't have to add -mattr=+c on the command line.
Differential Revision: https://reviews.llvm.org/D42629
llvm-svn: 324058
When the compressed instruction set is enabled, the 16-bit c.nop can be
generated if necessary.
Differential Revision: https://reviews.llvm.org/D41221
Patch by Shiva Chen.
llvm-svn: 322658
c.slli/c.srli/c.srai allow a 5-bit shift in RV32C and a 6-bit shift in RV64C.
This patch adds uimmlog2xlennonzero to reflect this constraint as well as
tests.
Differential Revision: https://reviews.llvm.org/D41216
Patch by Shiva Chen.
llvm-svn: 320799
This patch switches the default for -riscv-no-aliases to false
and updates all affected MC and CodeGen tests. As recommended in
D41071, MC tests use the canonical instructions and the CodeGen
tests use the aliases.
Additionally, for the f and d instructions with rounding mode,
the tests for the aliased versions are moved and tightened such
that they can actually detect if alias emission is enabled.
(see D40902 for context)
Differential Revision: https://reviews.llvm.org/D41225
Patch by Mario Werner.
llvm-svn: 320797
Unfortunately these aren't defined explicitly in the privileged spec, but the
GNU assembler does accept `sfence.vma` and `sfence.vma rs` as well as the
usual `sfence.vma rs, rt`.
llvm-svn: 320575
Adds the assembler aliases for the floating point instructions
which can be mapped to a single canonical instruction. The missing
pseudo instructions (flw, fld, fsw, fsd) are marked as TODO. Other
things, like for example PCREL_LO, have to be implemented first.
This patch builds upon D40902.
Differential Revision: https://reviews.llvm.org/D41071
Patch by Mario Werner.
llvm-svn: 320569
Adds the assembler pseudo instructions of RV32I and RV64I which can
be mapped to a single canonical instruction. The missing pseudo
instructions (e.g., call, tail, ...) are marked as TODO. Other
things, like for example PCREL_LO, have to be implemented first.
Currently, alias emission is disabled by default to keep the patch
minimal. Alias emission by default will be enabled in a subsequent
patch which also updates all affected tests. Note that this patch
should actually break the floating point MC tests. However, the
used FileCheck configuration is not tight enought to detect the
breakage.
Differential Revision: https://reviews.llvm.org/D40902
Patch by Mario Werner.
llvm-svn: 320487
As the FPR32 and FPR64 registers have the same names, use
validateTargetOperandClass in RISCVAsmParser to coerce a parsed FPR32 to an
FPR64 when necessary. The rest of this patch is very similar to the RV32F
patch.
Differential Revision: https://reviews.llvm.org/D39895
llvm-svn: 320023
The most interesting part of this patch is probably the handling of
rounding mode arguments. Sadly, the RISC-V assembler handles floating point
rounding modes as a special "argument" when it would be more consistent to
handle them like the atomics, opcode suffixes. This patch supports parsing
this optional parameter, using InstAlias to allow parsing these floating point
instructions when no rounding mode is specified.
Differential Revision: https://reviews.llvm.org/D39893
llvm-svn: 320020
