It is more logical, it cleans up the code and it makes implicit
operand size override prefixes come out in the same order as explicit
ones instead of after all other prefixes.
Suggested-by: H. Peter Anvin <hpa@zytor.com>
calcsize() had the wrong criterion for when C5 prefixes are permitted
(REX.R is permitted, REX.X is forbidden.) assemble() had the right
test already. This caused symbol value errors.
The implicit operand size override code didn't set the operand size
prefix, which confused the size calculation code for the range check.
The BITS 64 operand size calculation is still off, but "fixing" it by
making it 32-bit unless REX.W is set breaks PUSH and maybe others.
Change the .wx (ignore the W field) to .wig, to match the latest
version of the AVX specification. This is not a functional change,
but just makes instruction patterns a little easier to write.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Two fixes:
1. Optimization of [bx+0xFFFF] etc
0xFFFF is an sbyte under 16-bit semantics,
so make sure to check it right.
2. Don't optimize displacements in -O0
Displacements that fit into an sbyte or
can be removed should *not* be optimized in -O0.
Implicit zero displacements are still optimized, e.g.:
[eax] -> 0 bit displacement, [ebp] -> 8 bit displacement.
However explicit displacements are not optimized:
[eax+0] -> 32 bit displacement, [ebp+0] -> 32 bit displacement.
Because #2 breaks compatibility with 0.98,
I introduced a new optimization level: -OL, legacy.
Add OUT_REL1ADR (one-byte relative address) and support for
OUT_ADDRESs with size == 1. Add support for it in
outbin and outdbg. *It still needs to be added to other backends*,
both the OUT_REL*ADR and OUT_ADDRESS codepaths need to be handled.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Check if the offset and the representation are equivalent.
Disallow REL on absolute addresses.
I'm not sure what that would mean and the output formats don't support it.
Warn about ignored displacement size modifiers.
We may throw out j variable (since we break anyway)
and don't assign asize for free (since we don't
use it after).
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Hopefully this should catch all of them... but please keep an eye out
for any other uses of int32_t for the operand flags.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
is_class does not checking flags "strictly". Which means
it may fail if type is specified to REGMEM and you check for
is_class(MEMORY, ...).
Anyway in current patch we check for REGISTER which doesn't
overlap and it is safe to use is_class here.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Do an "exclusive" test for a REGISTER operand when deciding to treat
sizes as wildcards. "Exclusive" meaning don't just accept any class
that could be REGISTER, but something that is strictly a part of the
REGISTER class.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Register with no size are a bit special: we don't honor extrinsic
register sizes in the first place ("oword xmm1" gives a warning,
even), and they should match any xmmrm size. As such, explicitly
handle sizeless register operands as a hard match, instead of relying
on the fuzzy-matching mechanism to handle them.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Consolidate I_none opcode to be used everywhere
instead of mix (-1,I_none).
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Clear an uninitialized variable warning. The case can't actually
happen, but the compiler doesn't know that.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Defer the "operand size missing" error until we know all the other
operands have the correct type. Otherwise we'll end up with false
positives, which result in noise entered into the xsizeflags array,
thus causing fuzzy matching to fail.
It's possible we should defer it even further.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This allows automatic fuzzy matching of operand sizes. If an operand
size is not specified, but there is exactly one possible size for the
instruction, select that instruction size. This requires a second
pass through the instruction patterns, and so is slightly slower, but
should be a lot easier to get right than the S- flags, and works even
when there is more than one instruction.
The new SX (Size eXact) flag can be used to prevent fuzzy matching
completely.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Move the instruction-matching loop into a common function. This gives
us a single point to adjust the instruction-selection algorithm.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
*To the best of my knowledge*, we now have authorization from everyone
who has significantly contributed to NASM in the past. As such,
change the license to the 2-clause BSD license.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Add copyright headers to the *.c/*.h files in the main directory. For
files where I'm sure enough that we have all the approvals, I have
given them the 2-BSD license, the others have been given the "LGPL for
now" license header. Most of them can probably be changed after
auditing.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Fix the disassembly of JRCXZ; in 64-bit mode, we should only accept
JECXZ for disassembly with 32-bit address size override.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Add a byte code to explicitly support instructions which only uses the
low 8-bit registers (as if a REX prefix always was present.) This is
usable for instructions which are officially documented as using "the
low byte of a 32-bit register" and so on.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Handle AMD's XOP prefixes; they use basically the same encoding as VEX
prefixes, so treat them simply as a variant of VEX.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Optimize displacements, don't pessimize them. When running in the
optimizer, we always keep track of when a reference is forward. That
doesn't mean it is unknown.
Only be optimistic about the reachability of a symbol with NO_SEG if
we are truly in pass 1, i.e. it could possibly be just a forward
reference. After we have done a single pass, if it is still NO_SEG,
then it is an absolute symbol and need to be treated as such.
WAIT is technically an instruction, but from an assembler standpoint
it behaves as if it had been a prefix. In particular, it has to be
ordered *before* any real hardware prefixes.
We have a number of all-zero buffers in the code. Put a single
all-zero buffer in nasmlib.c. Additionally, add fwritezero()
which can be used to write an arbitrary number of all-zero bytes;
this prevents the situation where the all-zero buffer is simply
too small.
