[llvm-exegesis] Exploring X86::OperandType::OPERAND_COND_CODE
Summary:
Currently, we only have nice exploration for LEA instruction,
while for the rest, we rely on `randomizeUnsetVariables()`
to sometimes generate something interesting.
While that works, it isn't very reliable in coverage :)
Here, i'm making an assumption that while we may want to explore
multi-instruction configs, we are most interested in the
characteristics of the main instruction we were asked about.
Which we can do, by taking the existing `randomizeMCOperand()`,
and turning it on it's head - instead of relying on it to randomly fill
one of the interesting values, let's pregenerate all the possible interesting
values for the variable, and then generate as much `InstructionTemplate`
combinations of these possible values for variables as needed/possible.
Of course, that requires invasive changes to no longer pass just the
naked `Instruction`, but sometimes partially filled `InstructionTemplate`.
As it can be seen from the test, this allows us to explore
`X86::OperandType::OPERAND_COND_CODE` for instructions
that take such an operand.
I'm hoping this will greatly simplify exploration.
Reviewers: courbet, gchatelet
Reviewed By: gchatelet
Subscribers: orodley, mgorny, sdardis, tschuett, jrtc27, atanasyan, mstojanovic, andreadb, RKSimon, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74156
diff --git a/llvm/tools/llvm-exegesis/lib/Target.h b/llvm/tools/llvm-exegesis/lib/Target.h
index 1f35bfe..298cfac 100644
--- a/llvm/tools/llvm-exegesis/lib/Target.h
+++ b/llvm/tools/llvm-exegesis/lib/Target.h
@@ -126,6 +126,16 @@
return true;
}
+ // For some instructions, it is interesting to measure how it's performance
+ // characteristics differ depending on it's operands.
+ // This allows us to produce all the interesting variants.
+ virtual std::vector<InstructionTemplate>
+ generateInstructionVariants(const Instruction &Instr,
+ unsigned MaxConfigsPerOpcode) const {
+ // By default, we're happy with whatever randomizer will give us.
+ return {&Instr};
+ }
+
// Creates a snippet generator for the given mode.
std::unique_ptr<SnippetGenerator>
createSnippetGenerator(InstructionBenchmark::ModeE Mode,