These have very simple generators and no need for complex group
decoding. Apart from LAR/LSL which are simplified to use
gen_op_deposit_reg_v and movcond, the code is generally lifted
from translate.c into the generators.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SYSENTER is allowed in VM86 mode, but not in real mode. Split the check
so that PE and !VM86 are covered by separate bits.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is already partly implemented due to VLDMXCSR and VSTMXCSR; finish
the job.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is a bit more generic, as it can be applied to MPX as well.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CPUX86State argument would only be used to fetch bytes, but that has to be
done before the generator function is called. So remove it, and all
temptation together with it.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit fixes an issue with MOV instructions (0x8C and 0x8E)
involving segment registers; MOV to segment register's source is
16-bit, while MOV from segment register has to explicitly set the
memory operand size to 16 bits. Introduce a new flag
X86_SPECIAL_Op0_Mw to handle this specification correctly.
Signed-off-by: Xinyu Li <lixinyu20s@ict.ac.cn>
Message-ID: <20240602100528.2135717-1-lixinyu20s@ict.ac.cn>
Fixes: 5e9e21bcc4 ("target/i386: move 60-BF opcodes to new decoder", 2024-05-07)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These are trivial to add, and moving them to the new decoder fixes some
corner cases: raising #UD instead of an instruction fetch page fault for
the undefined opcodes, and incorrectly rejecting 0F 18 prefetches with
register operands (which are treated as reserved NOPs).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move long-displacement Jcc, SETcc and CMOVcc to the new decoder.
While filling in the tables makes the code seem longer, the new
emitters are all just one line of code.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The shift instructions are rewritten instead of reusing code from the old
decoder. Rotates use CC_OP_ADCOX more extensively and generally rely
more on the optimizer, so that the code generators are shared between
the immediate-count and variable-count cases.
In particular, this makes gen_RCL and gen_RCR pretty efficient for the
count == 1 case, which becomes (apart from a few extra movs) something like:
(compute_cc_all if needed)
// save old value for OF calculation
mov cc_src2, T0
// the bulk of RCL is just this!
deposit T0, cc_src, T0, 1, TARGET_LONG_BITS - 1
// compute carry
shr cc_dst, cc_src2, length - 1
and cc_dst, cc_dst, 1
// compute overflow
xor cc_src2, cc_src2, T0
extract cc_src2, cc_src2, length - 1, 1
32-bit MUL and IMUL are also slightly more efficient on 64-bit hosts.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Compared to the old decoder, the main differences in translation
are for the little-used ARPL instruction. IMUL is adjusted a bit
to share more code to produce flags, but is otherwise very similar.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While keeping decode->immediate for convenience and for 4-operand instructions,
store the immediate in X86DecodedOp as well. This enables instructions
with more than one immediate such as ENTER. It can also be used for far
calls and jumps.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The main difficulty here is that a page fault when writing to the destination
must not overwrite the flags. Therefore, the flags computation must be
inlined instead of using gen_jcc1*.
For simplicity, I am using an unconditional cmpxchg operation, that becomes
a NOP if the comparison fails.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
ALU instructions can write to both memory and flags. If the CC_SRC*
and CC_DST locations have been written already when a memory access
causes a fault, the value in CC_SRC* and CC_DST might be interpreted
with the wrong CC_OP (the one that is in effect before the instruction.
Besides just using the wrong result for the flags, something like
subtracting -1 can have disastrous effects if the current CC_OP is
CC_OP_EFLAGS: this is because QEMU does not expect bits outside the ALU
flags to be set in CC_SRC, and env->eflags can end up set to all-ones.
In the case of the attached testcase, this sets IOPL to 3 and would
cause an assertion failure if SUB is moved to the new decoder.
This mechanism is not really needed for BMI instructions, which can
only write to a register, but put it to use anyway for cleanliness.
In the case of BZHI, the code has to be modified slightly to ensure
that decode->cc_src is written, otherwise the new assertions trigger.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Usually the registers are just moved into s->T0 without much care for
their operand size. However, in some cases we can get more efficient
code if the operand fetching logic syncs with the emission function
on what is nicer.
All the current uses are mostly demonstrative and only reduce the code
in the emission functions, because the instructions do not support
memory operands. However the logic is generic and applies to several
more instructions such as MOVSXD (aka movslq), one-byte shift
instructions, multiplications, XLAT, and indirect calls/jumps.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
X86_SPECIAL_ZExtOp0 and X86_SPECIAL_ZExtOp2 are poorly named; they are a hack
that is needed by scalar insertion and extraction instructions, and not really
related to zero extension: for PEXTR the zero extension is done by the generation
functions, for PINSR the high bits are not used at all and in fact are *not*
filled with zeroes when loaded into s->T1.
Rename the values to match the effect described in the manual, and explain
better in the comments.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The previous check erroneously allowed CMP to be modified with LOCK.
Instead, tag explicitly the instructions that do support LOCK.
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instructions in VEX exception class 6 generally look at the value of
VEX.W. Note that the manual places some instructions incorrectly in
class 4, for example VPERMQ which has no non-VEX encoding and no legacy
SSE analogue. AMD does a mess of its own, as documented in the comment
that this patch adds.
Most of them are checked for VEX.W=0, and are listed in the manual
(though with an omission) in table 2-16; VPERMQ and VPERMPD check for
VEX.W=1, which is only listed in the instruction description. Others,
such as VPSRLV, VPSLLV and the FMA3 instructions, use VEX.W to switch
between a 32-bit and 64-bit operation.
Fix more of the class 4/class 6 mismatches, and implement the check for
VEX.W in TCG.
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation for adding more similar checks, move the VEX.L=0 check
and several X86_SPECIAL_* checks to a new field, where each bit represent
a common check on unused bits, or a restriction on the processor mode.
Likewise, many SVM intercepts can be checked during the decoding phase,
the main exception being the selective CR0 write, MSR and IOIO intercepts.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The implementation was validated with OpenSSL and with the test vectors in
https://github.com/rust-lang/stdarch/blob/master/crates/core_arch/src/x86/sha.rs.
The instructions provide a ~25% improvement on hashing a 64 MiB file:
runtime goes down from 1.8 seconds to 1.4 seconds; instruction count on
the host goes down from 5.8 billion to 4.8 billion with slightly better
IPC too. Good job Intel. ;)
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CVTPS2PD only loads a half-register for memory, like CVTPH2PS. It can
reuse the "ph" packed half-precision size to load a half-register,
but rename it to "xh" because it is now a variation of "x" (it is not
used only for half-precision values).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The only issue with FMA instructions is that there are _a lot_ of them (30
opcodes, each of which comes in up to 4 versions depending on VEX.W and
VEX.L; a total of 96 possibilities). However, they can be implement with
only 6 helpers, two for scalar operations and four for packed operations.
(Scalar versions do not do any merging; they only affect the bottom 32
or 64 bits of the output operand. Therefore, there is no separate XMM
and YMM of the scalar helpers).
First, we can reduce the number of helpers to one third by passing four
operands (one output and three inputs); the reordering of which operands
go to the multiply and which go to the add is done in emit.c.
Second, the different instructions also dispatch to the same softfloat
function, so the flags for float32_muladd and float64_muladd are passed
in the helper as int arguments, with a little extra complication to
handle FMADDSUB and FMSUBADD.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
F16C only consists of two instructions, which are a bit peculiar
nevertheless.
First, they access only the low half of an YMM or XMM register for the
packed-half operand; the exact size still depends on the VEX.L flag.
This is similar to the existing avx_movx flag, but not exactly because
avx_movx is hardcoded to affect operand 2. To this end I added a "ph"
format name; it's possible to reuse this approach for the VPMOVSX and
VPMOVZX instructions, though that would also require adding two more
formats for the low-quarter and low-eighth of an operand.
Second, VCVTPS2PH is somewhat weird because it *stores* the result of
the instruction into memory rather than loading it.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This adds another kind of weirdness when you thought you had seen it all:
an opcode byte that comes _after_ the address, not before. It's not
worth adding a new X86_SPECIAL_* constant for it, but it's actually
not unlike VCMP; so, forgive me for exploiting the similarity and just
deciding to dispatch to the right gen_helper_* call in a single code
generation function.
In fact, the old decoder had a bug where s->rip_offset should have
been set to 1 for 3DNow! instructions, and it's fixed now.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There are several special cases here:
1) extending moves have different widths for the helpers vs. for the
memory loads, and the width for memory loads depends on VEX.L too.
This is represented by X86_SPECIAL_AVXExtMov.
2) some instructions, such as variable-width shifts, select the vector element
size via REX.W.
3) VSIB instructions (VGATHERxPy, VPGATHERxy) are also part of this group,
and they have (among other things) two output operands.
3) the macros for 4-operand blends (which are under 0x0f 0x3a) have to be
extended to support 2-operand blends. The 2-operand variant actually
came a few years earlier, but it is clearer to implement them in the
opposite order.
X86_TYPE_WM, introduced earlier for unaligned loads, is reused for helpers
that accept a Reg* but have a M argument.
These three-byte opcodes also include AVX new instructions, for which
the helpers were originally implemented by Paul Brook <paul@nowt.org>.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The more complicated ones here are d6-d7, e6-e7, f7. The others
are trivial.
For LDDQU, using gen_load_sse directly might corrupt the register if
the second part of the load fails. Therefore, add a custom X86_TYPE_WM
value; like X86_TYPE_W it does call gen_load(), but it also rejects a
value of 11 in the ModRM field like X86_TYPE_M.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Many SSE and AVX instructions are only valid with specific prefixes
(none, 66, F3, F2). Introduce a direct way to encode this in the
decoding table to avoid using decode groups too much.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add generic code generation that takes care of preparing operands
around calls to decode.e.gen in a table-driven manner, so that ALU
operations need not take care of that.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new decoder is based on three principles:
- use mostly table-driven decoding, using tables derived as much as possible
from the Intel manual. Centralizing the decode the operands makes it
more homogeneous, for example all immediates are signed. All modrm
handling is in one function, and can be shared between SSE and ALU
instructions (including XMM<->GPR instructions). The SSE/AVX decoder
will also not have duplicated code between the 0F, 0F38 and 0F3A tables.
- keep the code as "non-branchy" as possible. Generally, the code for
the new decoder is more verbose, but the control flow is simpler.
Conditionals are not nested and have small bodies. All instruction
groups are resolved even before operands are decoded, and code
generation is separated as much as possible within small functions
that only handle one instruction each.
- keep address generation and (for ALU operands) memory loads and writeback
as much in common code as possible. All ALU operations for example
are implemented as T0=f(T0,T1). For non-ALU instructions,
read-modify-write memory operations are rare, but registers do not
have TCGv equivalents: therefore, the common logic sets up pointer
temporaries with the operands, while load and writeback are handled
by gvec or by helpers.
These principles make future code review and extensibility simpler, at
the cost of having a relatively large amount of code in the form of this
patch. Even EVEX should not be _too_ hard to implement (it's just a crazy
large amount of possibilities).
This patch introduces the main decoder flow, and integrates the old
decoder with the new one. The old decoder takes care of parsing
prefixes and then optionally drops to the new one. The changes to the
old decoder are minimal and allow it to be replaced incrementally with
the new one.
There is a debugging mechanism through a "LIMIT" environment variable.
In user-mode emulation, the variable is the number of instructions
decoded by the new decoder before permanently switching to the old one.
In system emulation, the variable is the highest opcode that is decoded
by the new decoder (this is less friendly, but it's the best that can
be done without requiring deterministic execution).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
