The x86 decoder had no XOP (AMD 8F escape) support and read 8F E8.. as
POP r/m, losing instruction boundaries. Since #2238 roots code addresses
taken by RIP-relative LEA, code analysis reaches CPU-dispatched XOP
paths, such as the vpperm routines in Stremio Plus (PPSA74126), OpenNOW
(PPSA99082) and PPSA99420, and their Windows conversion failed with
"Code analysis: overlapping instruction boundaries". Decode 8F followed
by a map of 8 or more as a three-byte XOP prefix (8F can only be POP r/m
with ModRM.reg 0) with a ModRM operand, an 8-bit immediate in map 8 and
a 32-bit immediate in map 0Ah, in both the length and operand decoders.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
UD1 (0F B9 /r) always raises #UD, like UD2, but DecodeInstruction
reported it as sequential. Reachability analysis then followed the
bytes after it, so an import reachable only through that fallthrough
was kept by the strict unused NID filter. UD1 keeps its ModRM, so a
RIP-relative operand is still reported.
PUSH GS, POP GS and RSM (0F A8, 0F A9, 0F AA) have no ModRM byte, but fell in the 0F A3-AB ModRM range, so the decoder read the next byte as a ModRM and sized its displacement. MOV to and from control and debug registers (0F 20-23) ignore the ModRM mod field and always name a register, but were sized and reported as memory forms, including a RIP-relative disp32 for mod 00 r/m 101.
The decoder adds the TEST immediate of opcodes F6 and F7 when ModRM.reg
is 0 or 1. The check excluded VEX and two-byte opcodes but not EVEX, so
an EVEX.0F F6 (VPSADBW) whose ModRM.reg is 0 or 1 was given an extra
imm8 and decoded one byte too long. VPSADBW has no immediate (Intel SDM
Vol. 2B, VPSADBW).
A0-A3 (MOV AL/eAX/rAX to and from moffs) have no ModRM byte and carry an
8-byte absolute address in 64-bit mode, or 4 bytes with a 0x67 prefix.
The decoder added nothing for the address, so the linear scanner decoded
the address bytes as code.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
In 64-bit mode REX.W takes precedence over the 0x66 operand-size prefix,
so the immediate of 81, C7, 69, 68, A9, the 05..3D accumulator forms and
the F7 TEST form stays imm32. The decoder only applied this to B8+r and
returned a length two bytes short for the others.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DecodeInstruction returned before the ModRM byte for VEX and EVEX and
read the third opcode byte of 0F 38/0F 3A as ModRM, so their
RIP-relative operands were never reported. --to-intel then moved such an
instruction after a short EXTRQ/INSERTQ into the stub with its
displacement unchanged, and the strict unused-import filter missed its
references.
Co-Authored-By: Claude <noreply@anthropic.com>
In 64-bit mode a REX prefix only takes effect when it immediately
precedes the opcode; a REX followed by a legacy prefix or another REX is
ignored. The instruction decoder, the rewriter's reference classifier,
DecodedInstruction and the SSE4a, SHA-256 and CLZERO operand decoders
read legacy prefixes and then at most one REX. `48 F3 0F 2B 00`
(MOVNTSS) was therefore scanned as `[48 F3][0F 2B 00]` and kept, and
`48 67 0F 01 FC` lost its address-size prefix.
All of them now accept REX bytes among the prefixes and keep only one
that directly precedes the opcode. The converter's guard against
prefix-only fragments is removed, since the decoder no longer produces
them, and the TechnicalDebt entry describing the split is dropped.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
EXTRQ, INSERTQ, MOVNTSS and MOVNTSD are rewritten at relink time: same-length in-place forms
where they exist, otherwise a jmp rel32 into an appended executable section holding a
scratch-free SSE body and a jump back, so no code shifts and no RIP-relative or jump-table
operand needs adjusting. Decoder fixes for POPCNT and 0F BB (BTC), codegen and elfpatcher
tests, README and technical-debt notes. The runtime illegal-instruction trap stays as a
fallback.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177gthrWEBBfBu5xJDXgBfo
Achraf Reyani
Suryansh Prajapati
Dean
Adrià
overlordxrz-source
Oguzhan Ozdemir
Adrià Franch
ljkx
SamG-Coder
devilismyfriend
boykopovar