efriedma added inline comments.
================
Comment at: clang/lib/CodeGen/CGExprScalar.cpp:2120
+ } else
+ Addr = EmitLValue(E).getAddress(CGF);
Addr = Builder.CreateElementBitCast(Addr, CGF.ConvertTypeForMem(DestTy));
----------------
junparser wrote:
> junparser wrote:
> > efriedma wrote:
> > > I don't think it's legal to use EmitLValue here at all; the emitted IR
> > > could have side-effects.
> > >
> > > Since we have the vector insert/extract intrinsics now, can we just use
> > > them here instead of going through the load/store dance?
> > > I don't think it's legal to use EmitLValue here at all; the emitted IR
> > > could have side-effects.
> > >
> > I agree since we have already visited E.
> >
> > > Since we have the vector insert/extract intrinsics now, can we just use
> > > them here instead of going through the load/store dance?
> >
> > we have already use insert/extract intrinsics for same element type, we can
> > only handle predicate cast through memory.
> > One of idea here is always use store + load. what do you think?
> >
> @efriedma I'm also working on a patch that optimize such store + bitcast +
> load pattern with constant vector, so maybe it is ok to always use alloca +
> load
I'd be happy to accept just unconditionally doing the alloca+store+load thing
for now.
Not sure I understand why predicates are special here. Even if we can't handle
predicates directly in insert/extract intrinsics, we can always just
zero-extend to a bigger integer type, do the cast, then truncate the result.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D105097/new/
https://reviews.llvm.org/D105097
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