Add support for flag output operand "=@cc" for SystemZ. (#125970)

Added Support for flag output operand "=@cc", inline assembly constraint
for
SystemZ.

- Clang now accepts "=@cc" assembly operands, and sets 2-bits condition
code
    for output operand for SyatemZ.

- Clang currently emits an assertion that flag output operands are
boolean
values, i.e. in the range [0, 2). Generalize this mechanism to allow
targets to specify arbitrary range assertions for any inline assembly
    output operand.  This will be used to assert that SystemZ two-bit
    condition-code values are in the range [0, 4).

- SystemZ backend lowers "@cc" targets by using ipm sequence to extract
    condition code from PSW.

  - DAGCombine tries to optimize lowered ipm sequence by combining
CCReg and computing effective CCMask and CCValid in combineCCMask for
    select_ccmask and br_ccmask.

- Cost computation is done for merging conditionals for branch
instruction
in SelectionDAG, as split may cause branches conditions evaluation goes
    across basic block and difficult to combine.

---------

Co-authored-by: anoopkg6 <anoopkg6@github.com>
Co-authored-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>

0 files changed, 0 insertions, 0 deletions