The 0x66 prefix toggles between 16-bit and 32-bit addressing mode.
So in 32-bit mode it is used to switch to 16-bit addressing mode for the
following instruction, while in 16-bit mode it's the other way round — it's
used to switch to 32-bit mode instead.
Thus, emit the 0x66 prefix byte for OpSize only in 32-bit (and 64-bit) mode,
and introduce a new OpSize16 bit which is used in 16-bit mode instead.
This is just the basic infrastructure for that change; a subsequent patch
will add the new OpSize16 bit to the 32-bit instructions that need it.
Patch from David Woodhouse.
llvm-svn: 198586
This is not really expected to work right yet. Mostly because we will
still emit the OpSize (0x66) prefix in all the wrong places, along with
a number of other corner cases. Those will all be fixed in the subsequent
commits.
Patch from David Woodhouse.
llvm-svn: 198584
Add some tests to validate correct register selection, including a fix
to an existing test which was requiring the *wrong* output.
Patch from David Woodhouse.
llvm-svn: 198566
Checking the trailing letter of the mnemonic is insufficient. Be more thorough
in the scanning of the instruction to ensure that we correctly work with the
predicated mnemonics.
llvm-svn: 198235
The GNU assembler supports .rep as an alias for .rept. This simply creates the
alias for it and introduces a test for both .rept and .rep.
llvm-svn: 198097
The bkpt mnemonic has an implicit immediate constant of 0 unless otherwise
specified. Add an instruction alias for the unvalued breakpoint mnemonic to
treat it as a 0. This improves compatibility with GNU AS.
Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>
llvm-svn: 197913
this commit as the only one on the Blamelist so I quickly reverted this.
However it was actually Nick's change who has since fixed that issue.
Original commit message:
Changed the X86 assembler for intel syntax to work with directional labels.
The X86 assembler as a separate code to parser the intel assembly syntax
in X86AsmParser::ParseIntelOperand(). This did not parse directional labels.
And if something like 1f was used as a branch target it would get an
"Unexpected token" error.
The fix starts in X86AsmParser::ParseIntelExpression() in the case for
AsmToken::Integer, it needs to grab the IntVal from the current token
then look for a 'b' or 'f' following an Integer. Then it basically needs to
do what is done in AsmParser::parsePrimaryExpr() for directional
labels. It saves the MCExpr it creates in the IntelExprStateMachine
in the Sym field.
When it returns to X86AsmParser::ParseIntelOperand() it looks
for a non-zero Sym field in the IntelExprStateMachine and if
set it creates a memory operand not an immediate operand
it would normally do for the Integer.
rdar://14961158
llvm-svn: 197744
The X86 assembler has a separate code to parser the intel assembly syntax
in X86AsmParser::ParseIntelOperand(). This did not parse directional labels.
And if something like 1f was used as a branch target it would get an
"Unexpected token" error.
The fix starts in X86AsmParser::ParseIntelExpression() in the case for
AsmToken::Integer, it needs to grab the IntVal from the current token
then look for a 'b' or 'f' following the Integer. Then it basically needs to
do what is done in AsmParser::parsePrimaryExpr() for directional
labels. It saves the MCExpr it creates in the IntelExprStateMachine
in the Sym field.
When it returns to X86AsmParser::ParseIntelOperand() it looks
for a non-zero Sym field in the IntelExprStateMachine and if
set it creates a memory operand not an immediate operand
it would normally do for the Integer.
rdar://14961158
llvm-svn: 197728
This directive will write out the assembler-maintained constant
pool for the current section. These constant pools are created to
support the ldr-pseudo instruction (e.g. ldr r0, =val).
The directive can be used by the programmer to place the constant
pool in a location that can be reached by a pc-relative offset in
the ldr instruction.
llvm-svn: 197711
The ldr-pseudo opcode is a convenience for loading 32-bit constants.
It is converted into a pc-relative load from a constant pool. For
example,
ldr r0, =0x10001
ldr r1, =bar
will generate this output in the final assembly
ldr r0, .Ltmp0
ldr r1, .Ltmp1
...
.Ltmp0: .long 0x10001
.Ltmp1: .long bar
Sketch of the LDR pseudo implementation:
Keep a map from Section => ConstantPool
When parsing ldr r0, =val
parse val as an MCExpr
get ConstantPool for current Section
Label = CreateTempSymbol()
remember val in ConstantPool at next free slot
add operand to ldr that is MCSymbolRef of Label
On finishParse() callback
Write out all non-empty constant pools
for each Entry in ConstantPool
Emit Entry.Label
Emit Entry.Value
Possible improvements to be added in a later patch:
1. Does not convert load of small constants to mov
(e.g. ldr r0, =0x1 => mov r0, 0x1)
2. Does reuse constant pool entries for same constant
The implementation was tested for ARM, Thumb1, and Thumb2 targets on
linux and darwin.
llvm-svn: 197708
The tests for the disassembler were adapted from the encoder tests, and for the
most part, the output from the disassembler matches that encoder-test inputs.
There are some places where more-informative mnemonics could be produced
(notably for the branch instructions), and those cases are noted in the tests
with FIXMEs.
Future work includes:
- Generating more-informative mnemonics when possible (this may also be done
in the printer).
- Remove the dependence on positional "numbered" operand-to-variable mapping
(for both encoding and decoding).
- Internally using 64-bit instruction variants in 64-bit mode (if this turns
out to matter).
llvm-svn: 197693
This adds support for the .inst directive. This is an ARM specific directive to
indicate an instruction encoded as a constant expression. The major difference
between .word, .short, or .byte and .inst is that the latter will be
disassembled as an instruction since it does not get flagged as data.
llvm-svn: 197657
The .end directive indicates the end of the file. No further instructions are
processed after a .end directive is encountered.
One potential (glaringly obvious) optimisation that could be pursued here is to
extend MCAsmParser with a DiscardRemainder method to avoid processing lexemes to
the end of the file. It was unclear at this point if that would be worth
adding, and could easily be added in a follow on change.
Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>
llvm-svn: 197547
Without this, assembling clang's disassembly would produce an object
file with the IMAGE_SCN_CNT_INITIALIZED_DATA section characteristic
rather than the uninitialized one. link.exe would warn when merging
comdats with different flags.
llvm-svn: 197529
were falling into the cases for 24-bit branch kinds which are not 24-bit
branches. The routine is to return false for fixups are expected to always
be resolvable at assembly time. Which these three fixups are as they have
limited displacement and are for local references within a function.
rdar://15586725
llvm-svn: 197282
branch instructions for mips and micromips instruction sets thus avoiding
the situation of generating branches to undesired locations if offsets
cannot be encoded.
This patch also checks if a fixup cannot be applied and returns a fatal error
if that's the case.
llvm-svn: 197223
As we can't make a complete solution now it has been decided to enable .set directive to handle long jump expressions. This will cause parser to report errors when parsing integer based register assignments, for example:
.set r3, will be reported as error. Still, the need for expressions is higher priority as the integer based register assignments are Mips specific and can be avoided using register names.
llvm-svn: 196773
The integrated assembler fails to properly lex arm comments when
they are adjacent to an identifier in the input stream. The reason
is that the arm comment symbol '@' is also used as symbol variant in
other assembly languages so when lexing an identifier it allows the
'@' symbol as part of the identifier.
Example:
$ cat comment.s
foo:
add r0, r0@got to parse this as a comment
$ llvm-mc -triple armv7 comment.s
comment.s:4:18: error: unexpected token in argument list
add r0, r0@got to parse this as a comment
^
This should be parsed as correctly as `add r0, r0`.
This commit modifes the assembly lexer to not include the '@' symbol
in identifiers when lexing for targets that use '@' for comments.
llvm-svn: 196607
not being correctly encoded/decoded.
In more detail, immediate fields of LD/ST instructions should be
divided/multiplied by the size of the data format before encoding and
after decoding, respectively.
llvm-svn: 196494
Venkatraman Govindaraju