[PATCH] D139283: [llvm-exegesis] parallel snippet generator: avoid Read-After-Write pitfail for instrs w/ tied variables

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri marked an inline comment as done.
lebedev.ri added inline comments.


================
Comment at: llvm/tools/llvm-exegesis/lib/ParallelSnippetGenerator.cpp:158
+
+  if (Op.isUse()) {
+    switch (S) {
----------------
RKSimon wrote:
> lebedev.ri wrote:
> > One thing i was thinking of, are there cases where we have
> > both defs with tied uses AND defs without tied uses?
> > If we have (which instruction is that?),
> > should we just always reuse the reg for defs without tied uses?
> The weirdest x86 instructions for that kind of thing are some of the CMPXCHG reg-reg instructions - maybe some of the MUL/IMUL and DIV/IDIV variants as well?
What i would like, is `--dry-run` option for exegesis,
to do everything, EXCEPT actually running the measurements.
It will help with test coverage, too.
If that option was present, i would have an easy way to check if there is such an opcode...


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D139283/new/

https://reviews.llvm.org/D139283