Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3637,IMPALA-3636: refactor codegen constant replacement
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Patch Set 5:

(3 comments)

http://gerrit.cloudera.org:8080/#/c/3401/5/be/src/codegen/llvm-codegen.cc
File be/src/codegen/llvm-codegen.cc:

Line 767: char ConstantReplacementPass::pass_id_ = 0;
> I think you can make this a constexpr and do in-class initialization
For some reason the LLVM API wants this passed by reference, which prevents 
doing that (we need the char in a byte of memory somewhere, and I guess 
constexpr doesn't do that).

http://llvm.org/docs/doxygen/html/classllvm_1_1FunctionPass.html


http://gerrit.cloudera.org:8080/#/c/3401/4/be/src/exprs/expr.cc
File be/src/exprs/expr.cc:

Line 599:     } else {
> This looks unchanged to me in PS5. Do you mean "Done" as in "Considered; de
Ah, I made the change in the function below but not here. The previous code was 
safe, since it took the else branch anyway, but had an unnecessary level of 
nesting there.


http://gerrit.cloudera.org:8080/#/c/3401/4/be/src/util/cpu-info.cc
File be/src/util/cpu-info.cc:

PS4, Line 202: 
> Can you elaborate to me on why a static initializer would be very unlikely 
We do it much later in the process lifecycle (well after the process is set up 
and accepting queries).

Aside from that, if a different static initialiser was doing codegen and 
assuming a bunch of static state was initialised, it would be the one violating 
the "don't do anything non-trivial in static initialisers" rule. There's a 
bunch of LLVM global state that needs to be initialised before doing any 
codegen (see be/src/codegen/llvm-codegen.cc:104) so you'd really have to go to 
great lengths to do it.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I6ba029ed8589698eb15dbfb0a20dd2a7ea752635
Gerrit-PatchSet: 5
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Jim Apple <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
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