These instructions read their inputs from fixed registers rather
than using a modrm byte. We shouldn't require the user to list them
when parsing assembly. This matches the GNU assembler.
This patch adds InstAliases so we can accept either form. It also
changes the printing code to use the form without registers. This
will change the behavior of llvm-objdump, but should be consistent
with binutils objdump. This also matches what we already do in LLVM for
clzero and monitorx which also used fixed registers.
I need to add and improve tests before this can be commited. The
disassembler tests exist, but weren't checking the fixed register
so they pass before and after this change.
Fixes https://github.com/ClangBuiltLinux/linux/issues/1216
Differential Revision: https://reviews.llvm.org/D93524
We need to make sure not to emit R_X86_64_GOTPCRELX relocations for
instructions that use a REX prefix. If a REX prefix is present, we need to
instead use a R_X86_64_REX_GOTPCRELX relocation. The existing logic for
CALL64m, JMP64m, etc. already handles this by checking the HasREX parameter
and using it to determine which relocation type to use. Do this for all
instructions that can use relaxed relocations.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D93561
The REX prefix is needed to allow linker relaxations: even if the
instruction we emit may not need it, the linker may change it to a
different instruction which does need it.
clang may produce `movl x@GOTPCREL+4(%rip), %eax` when loading the high
32 bits of the address of a global variable in -fpic/-fpie mode.
If assembled by GNU as, the fixup emits R_X86_64_GOTPCRELX with an addend != -4.
The instruction loads from the GOT entry with an offset and thus it is incorrect
to relax the instruction.
This patch does not emit a relaxable relocation for a GOT load with an offset
because R_X86_64_[REX_]GOTPCRELX do not make sense for instructions which cannot
be relaxed. The result is good enough for LLD to work. GNU ld relaxes
mov+GOTPCREL as well, but it suppresses the relaxation if addend != -4.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D92114
I was trying to add .cfi_ annotations to assembly code in the FreeBSD
kernel and changed a macro that then resulted in incorrectly nested
directives. However, clang's diagnostics said the error was happening at
<unknown>:0. This addresses one of the TODOs added in D51695.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D89787
This patch mainly made the following changes:
1. Support AVX-VNNI instructions;
2. Introduce ExplicitVEXPrefix flag so that vpdpbusd/vpdpbusds/vpdpbusds/vpdpbusds instructions only use vex-encoding when user explicity add {vex} prefix.
Differential Revision: https://reviews.llvm.org/D89105
We have been producing R_X86_64_REX_GOTPCRELX (MOV64rm/TEST64rm/...) and
R_X86_64_GOTPCRELX for CALL64m/JMP64m without the REX prefix since 2016 (to be
consistent with GNU as), but not for MOV32rm/TEST32rm/...
PR47632
This allows MC to match `data32 ...` as one instruction instead of two (data32 without insn + insn).
The compatibility with GNU as improves: `data32 ljmp` will be matched as ljmpl.
`data32 lgdt 4(%eax)` will be matched as `lgdtl` (prefixes: 0x67 0x66, instead
of 0x66 0x67).
GNU as supports many other `data32 *w` as `*l`. We currently just hard code
`data32 callw` and `data32 ljmpw`. Generalizing the suffix replacement is
tricky and requires a think about the "bwlq" appending suffix rules in MatchAndEmitATTInstruction.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D88772
Register context information was already being passed into the DWARFDebugFrame code that dumps unwind information but it wasn't being used. This change adds the ability to dump registers names of a valid MC register context was passed in and if it knows about the register. Updated the tests to use the newly returned register names.
Differential Revision: https://reviews.llvm.org/D88767
Key Locker provides a mechanism to encrypt and decrypt data with an AES key without having access
to the raw key value by converting AES keys into “handles”. These handles can be used to perform the
same encryption and decryption operations as the original AES keys, but they only work on the current
system and only until they are revoked. If software revokes Key Locker handles (e.g., on a reboot),
then any previous handles can no longer be used.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D88398
Used by kexec-tools (PR46942)
In GNU as, tc-i386.c:output_jump uses 4-byte immediate if a data32 prefix is present.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D88137
This is an older syntax than the {disp32} and {disp8} pseudo
prefixes that were added a few weeks ago. We can reuse most of
the support for that to support .d32 and .d8 as well.
These prefixes should override the default behavior and force a larger immediate size. I don't believe gas issues any warning if you use {disp8} when a 32-bit displacement is already required. And this patch doesn't either.
This completes the {disp8} and {disp32} support from PR46650.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D84793
We parse .arch so that some `.arch i386; .code32` code can assemble. It seems
that X86AsmParser does not do a good job tracking what features are needed to
assemble instructions. GNU as's x86 port supports a very wide range of .arch
operands. Ignore the operand for now.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D84900
A '*' after the segment is equivalent to a '*' before the segment register. To make the AsmMatcher table work we need to place the '*' token into the operand vector before the full memory operand. To accomplish this I've modified some portions of operand parsing to expose the operand vector to ParseATTOperand so that the token can be pushed to the vector after parsing the segment register and before creating the memory operand using that segment register.
Fixes PR46879
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D84895
By default we pick a 1 byte displacement and let relaxation enlarge it if necessary. The GNU assembler supports a pseudo prefix to basically pre-relax the instruction the larger size.
I plan to add {disp8} and {disp32} support for memory operands in another patch which is why I've included the parsing code and enum for {disp8} pseudo prefix as well.
Reviewed By: echristo
Differential Revision: https://reviews.llvm.org/D84709
In 16-bit mode we can encode a 32-bit address using 0x67 prefix.
We were failing to do this when the index register was a 32-bit
register, the base register was not present, and the displacement
fit in 16-bits.
Fixes PR46866.
Previously we only accepted a 32-bit source with a 64-bit dest.
Accepting 64-bit as well is more consistent with gas behavior. I
think maybe we should accept 16 bit register as well, but I'm not
sure.
We were missing the modrm byte this instruction has according
to current Intel SDM. Experiments with gcc indicate that different
modrm values are chosen based on 2 operands so I've added those
as well.
I think our previous implementation was based on an older behavior of
binutils that has since been changed.
The spec for these says they need 0xf3 but also mentions REP
before the mnemonic. But I don't think its fair to users to make
them write REP first. And gas doesn't make them. objdump seems to
disassemble with or without the prefix and just prints any 0xf3
as REP.
ffmpeg/libavcodec/x86/h264_cabac.c inline assembly may produce
movzb 1280(%rbx, %r12), %r12
After D80608, llvm-mc errors:
error: unknown use of instruction mnemonic without a size suffix
Summary:
Some instruction like VPMULDQ is NOT the variant of VPMULD but a new
one.
So we should make sure the suffix matcher only works for memory variant
that has the same size with the suffix.
Currently we only check for SSE/AVX* instructions, because many legacy
instructions didn't declare the alias instructions of their variants.
Differential Revision: https://reviews.llvm.org/D80608
This does the same thing as {vex2}. Which is give an error
if the instruction can't be done with VEX. It doesn't force
the instruction to use 2 byte VEX. That's already the preference
if its possible. Therefore {vex} is a clearer name.
Neither gcc or icc support this. Split out from D79472. I want
to remove more, but it looks like icc does support some things
gcc doesn't and I need to double check our internal test suites.
D63847 added `MCInstrAnalysis::evaluateMemoryOperandAddress()`. This patch
leverages the feature to print the target addresses for evaluable instructions.
```
-400a: movl 4080(%rip), %eax
+400a: movl 4080(%rip), %eax # 5000 <data1>
```
This patch also deletes `MIA->isCall(Inst) || MIA->isUnconditionalBranch(Inst) || MIA->isConditionalBranch(Inst)`
which is used to guard `MCInstrAnalysis::evaluateBranch()`
Reviewed By: jhenderson, skan
Differential Revision: https://reviews.llvm.org/D78776
Summary:
The instruction in non-text section can not be executed, so they will not affect performance.
In addition, their encoding values are treated as data, so we should not touch them.
Reviewers: MaskRay, reames, LuoYuanke, jyknight
Reviewed By: MaskRay
Subscribers: annita.zhang, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77971
For `.bss; nop`, MC inappropriately calls abort() (via report_fatal_error()) with a message
`cannot have fixups in virtual section!`
It is a bug to crash for invalid user input. Fix it by erroring out early in EmitInstToData().
Similarly, emitIntValue() in a virtual section (SHT_NOBITS in ELF) can crash with the mssage
`non-zero initializer found in section '.bss'` (see D4199)
It'd be nice to report the location but so many directives can call emitIntValue()
and it is difficult to track every location.
Note, COFF does not crash because MCAssembler::writeSectionData() is not
called for an IMAGE_SCN_CNT_UNINITIALIZED_DATA section.
Note, GNU as' arm64 backend reports ``Error: attempt to store non-zero value in section `.bss'``
for a non-zero .inst but fails to do so for other instructions.
We simply reject all instructions, even if the encoding is all zeros.
The Mach-O counterpart is D48517 (see `test/MC/MachO/zerofill-text.s`)
Reviewed By: rnk, skan
Differential Revision: https://reviews.llvm.org/D78138
As we disscussed in D77971, we haven't confirmed that if putting instructions
in a non-executable section is an undefined behaviour. To make things
easier to go on, we mark these sections executable in test file
align-branch-section-size.s.
Summary: We allow non-relaxable instructions emitted into relaxable Fragment when we prefix padding branch. So we need to check if the instruction need relaxation before relaxing it. Without this patch, it currently triggers a `report_fatal_error` in `llvm::MCAsmBackend::relaxInstruction` when we prefix padding branch along with `--mc-relax-all`.
Reviewers: LuoYuanke, reames, MaskRay
Reviewed By: MaskRay
Subscribers: MaskRay, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77851
Summary:
Since D75300 has been landed, I want to support enhanced relaxation when we need to align branches and allow prefix padding. "Enhanced Relaxtion" means we allow an instruction that could not be traditionally relaxed to be emitted into RelaxableFragment so that we increase its length by adding prefixes for optimization.
The motivation is straightforward, RelaxFragment is mostly for relative jumps and we can not increase the length of jumps when we need to align them, so if we need to achieve D75300's purpose (reducing the bytes of nops) when need to align jumps, we have to make more instructions "relaxable".
Reviewers: reames, MaskRay, craig.topper, LuoYuanke, jyknight
Reviewed By: reames
Subscribers: hiraditya, llvm-commits, annita.zhang
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76286
Craig Topper