[SelectionDAG] Handle more opcodes in canCreateUndefOrPoison (#84921)

[SelectionDAG] Handle more opcodes in canCreateUndefOrPoison

Handle SELECT_CC similarly as SETCC.

Handle these operations that only propagate poison/undef based on the
input operands:
  SADDSAT, UADDSAT, SSUBSAT, USUBSAT, MULHU, MULHS,
  SMIN, SMAX, UMIN, UMAX

These operations may create poison based on shift amount and exact
flag being violated:
  SRL, SRA

One goal here is to allow pushing freeze through these operations
when allowed, as well as letting analyses such as
isGuaranteedNotToBeUndefOrPoison to not break on such operations.

Since some problems have been observed with pushing freeze through
SRA/SRL we block that explicitly in DAGCombiner::visitFreeze now.
That way we can still model SRA/SRL properly in
SelectionDAG::canCreateUndefOrPoison, e.g. when used by
isGuaranteedNotToBeUndefOrPoison, even if we do not want to push
freeze through those instructions.

0 files changed, 0 insertions, 0 deletions