When GlobalISelEmitter::emitCxxPredicateFns emitted code for MI
predicates it used "PatFrag" when searching for definitions. With
this patch it will search for all "PatFrags" instead. Since PatFrag
derives from PatFrags the difference is that we now include all
definitions using PatFrags directly as well. Thus making it possible
to use GISelPredicateCode together with a PatFrags definition.
It might be noted that the matcher code was emitted also for PatFrags
in the past. But then one ended up with errors since the custom code
in testMIPredicate_MI was missing.
Differential Revision: https://reviews.llvm.org/D98486
Predicates with 'let PredicateCodeUsesOperands = 1' want to examine
matched operands. When we encounter predicate code that uses operands,
analyze its named operand arguments and create a map between argument
index and name. Later, when leaf node with name is encountered, emit
GIM_RecordNamedOperand that will store that operand at its argument
index in operand list. This operand list will be an argument to c++
code of the predicate.
Differential Revision: https://reviews.llvm.org/D87285
Currently custom code predicates can only really be used for
contextless checks tied to a single instruction (e.g. check the def
for hasOneUse). If you do want to inspect the input instructions in
the source pattern, you cannot without re-verifying the opcode and
type checks implied by the patterns, since this check was emitted
before any operand constraints. Really, these are pattern level
predicates that implicitly depend on the instruction and operand
checks.
Introduce a filtering function so the custom predicate is emitted
last. I'm not sure this is the most elegant solution. It seems like
this is really a different thing from the InstructionMatcher/IPM_
predicate kinds. I initially tried keeping this in a separate
predicate list, but that also seemed awkward.
This only half fixes the problem I'm trying to solve. The AMDGPU
pattern I'm attempting to port also uses the PredicateCodeUsesOperands
feature to allow checks on the source operands when the input pattern
is commuted. Really the emitter should reject the pattern since it
doesn't handle this case, but at this point it would be more
productive to just implement this.
Bjorn Pettersson