On 2013/07/29 14:44:59, danno wrote:
https://codereview.chromium.org/21014004/diff/1/src/hydrogen-instructions.cc
File src/hydrogen-instructions.cc (right):
https://codereview.chromium.org/21014004/diff/1/src/hydrogen-instructions.cc#newcode3076
src/hydrogen-instructions.cc:3076: void
HCompareObjectAndBranch::PrintDataTo(StringStream* stream) {
On 2013/07/29 13:24:41, titzer wrote:
> We should probably print the token now too, right?
Done.
https://codereview.chromium.org/21014004/diff/1/src/hydrogen-instructions.h
File src/hydrogen-instructions.h (right):
https://codereview.chromium.org/21014004/diff/1/src/hydrogen-instructions.h#newcode4175
src/hydrogen-instructions.h:4175: Token::Value token = Token::EQ) {
On 2013/07/29 13:24:41, titzer wrote:
> I looked, but I couldn't find any uses with the token == NE. We have the
> IfBuilder which can do IfNot, so do we need this parameterization?
It's used in a follow-on CL that I'm preparing, but I wanted to do this
incrementally. The problem with IfNot is that it just switches the
true/false
branch blocks. But the instructions that are output are still: "cmp XXXX,
b(eq,XXXX)", which makes the fall-through case always the not-equal case.
In
the
follow-on CL to convert numeric dictionary lookup to hydrogen that I'm
preparing, in order to generate the same code as the old assembly-language
version, the fall-through case needs to be the "ne" case, and it
measurably
affects performance if it isn't because it has to create extra jumps to
sort
of
the graph topology. Someday, out instruction selection should be able to
figure
this out itself, but that's unfortunately a long way off.
That makes sense. But maybe it would be better to make it explicit to the
backends which direction we expect the branch to go (via assume_taken or
assume_not_taken) instead of it implicitly assuming the branch to be not
taken
and then using EQ/NE.
https://codereview.chromium.org/21014004/
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