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

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: llvm/tools/llvm-exegesis/lib/ParallelSnippetGenerator.cpp:158
+
+  if (Op.isUse()) {
+    switch (S) {
----------------
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?


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

https://reviews.llvm.org/D139283