have 4 bits per register in the operand encoding), but have undefined
behavior when the operand value is 13 or 15 (SP and PC, respectively).
The trivial coalescer in linear scan sometimes will merge a copy from
SP into a subsequent instruction which uses the copy, and if that
instruction cannot legally reference SP, we get bad code such as:
mls r0,r9,r0,sp
instead of:
mov r2, sp
mls r0, r9, r0, r2
This patch adds a new register class for use by Thumb2 that excludes
the problematic registers (SP and PC) and is used instead of GPR
for those operands which cannot legally reference PC or SP. The
trivial coalescer explicitly requires that the register class
of the destination for the COPY instruction contain the source
register for the COPY to be considered for coalescing. This prevents
errant instructions like that above.
PR7499
llvm-svn: 109842
before reglist were not properly handled with respect to IT Block. Fix that by
creating a new method ARMBasicMCBuilder::DoPredicateOperands() used by those
instructions for disassembly. Add a test case.
llvm-svn: 101974
was asserting because the (RegClass, RegNum) combination doesn't make sense from
an encoding point of view.
Since getRegisterEnum() is used all over the place, to change the code to check
for encoding error after each call would not only bloat the code, but also make
it less readable. An Err flag is added to the ARMBasicMCBuilder where a client
can set a non-zero value to indicate some kind of error condition while building
up the MCInst. ARMBasicMCBuilder::BuildIt() checks this flag and returns false
if a non-zero value is detected.
llvm-svn: 101290
backend (ARMDecoderEmitter) which emits the decoder functions for ARM and Thumb,
and the disassembler core which invokes the decoder function and builds up the
MCInst based on the decoded Opcode.
Reviewed by Chris Latter and Bob Wilson.
llvm-svn: 100233
Bob Wilson