clin1 added inline comments.
Comment at: llvm/lib/Analysis/ConstantFolding.cpp:101
/// Constant fold bitcast, symbolically evaluating it with DataLayout.
/// This always returns a non-null constant, but it may be a
/// ConstantExpr if unfoldable.
xiangzhangllvm wrote:
> clin1 wrote:
> > API for this function always returns non-null: can we return
> > ConstantExpr::getBitCast(C,DestTy) instead? Then the change in SCCP is not
> > needed either.
> I tried, the SCCP will also fold the bitcast into the following instruction.
I see, that makes sense. But are we sure that all callers of FoldBitCast are
doing a null check: for example, FoldReinterpretLoadFromConstPtr calls
FoldBitCast several times, and null is not checked before dereference. Maybe
the AMX type cannot happen in this case?
Alternative: can AMX be checked in SCCP?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D98757/new/
https://reviews.llvm.org/D98757
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