16-bit literals are encoded as 32-bit values. If high 16-bits of the value is 0xFFFF, the decoded instruction cannot be reassembled.
For example, the following code
0xff,0x04,0x04,0x52,0xcd,0xab,0xff,0xff
was decoded as
v_mul_lo_u16_e32 v2, 0xffffabcd, v2
However this literal is actually a 64-bit constant 0x00000000ffffabcd which violates requirements described in the documentation - the truncation is not safe.
This change corrects decoding to make reassembly possible.
Reviewers: arsenm, rampitec
Differential Revision: https://reviews.llvm.org/D84098
Since 32-bit instructions with 32-bit input immediate behavior
are used to materialize 16-bit constants in 32-bit registers
for 16-bit instructions, determining the legality based
on the size is incorrect. Change operands to have the size
specified in the type.
Also adds a workaround for a disassembler bug that
produces an immediate MCOperand for an operand that
is supposed to be OPERAND_REGISTER.
The assembler appears to accept out of bounds immediates and
truncates them, but this seems to be an issue for 32-bit
already.
llvm-svn: 289306
Dmitry Preobrazhensky