jfb added inline comments.
================
Comment at: lib/Frontend/InitPreprocessor.cpp:305
@@ +304,3 @@
+ if (TypeWidth == TypeAlign && (TypeWidth & (TypeWidth - 1)) == 0 &&
+ TypeWidth <= InlineWidth)
+ return Always;
----------------
bcraig wrote:
> jyknight wrote:
> > jfb wrote:
> > > bcraig wrote:
> > > > On some targets (like Hexagon), 4-byte values are cheap to inline, but
> > > > 1-byte values are not. Clang is spotty about checking this, but
> > > > TargetInfo::hasBuiltinAtomic seems like the right function to ask, if
> > > > you have access to it.
> > > You're commenting on:
> > > ```
> > > if (TypeWidth == TypeAlign && (TypeWidth & (TypeWidth - 1)) == 0 &&
> > > TypeWidth <= InlineWidth)
> > > ```
> > > ?
> > >
> > > Are you asking for a separate change, or for a change to my patch?
> > That issue in clang's purview in any case; if hexagon wants to lower a
> > 1-byte cmpxchg to a compiler runtime function, it should do so in its
> > backend.
> I am asking for a change to this patch. Don't assume that all widths smaller
> than some value are inline-able and lock free, because that may not be the
> case. A 4 byte cmpxchg could be lock free, while a 1 byte cmpxchg may not be
> lock free.
Are you asking me to change this line:
```
if (TypeWidth == TypeAlign && (TypeWidth & (TypeWidth - 1)) == 0 &&
TypeWidth <= InlineWidth)
```
?
In what way?
Please be more specific.
http://reviews.llvm.org/D17950
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