rjmccall added inline comments.
================
Comment at: include/clang/Basic/TargetInfo.h:959
+ /// \brief Return the target address space which is read only and can be
+ /// casted to the generic address space.
+ virtual llvm::Optional<unsigned> getTargetConstantAddressSpace() const {
----------------
"Return an AST address space which can be used opportunistically for constant
global memory. It must be possible to convert pointers into this address space
to LangAS::Default. If no such address space exists, this may return None, and
such optimizations will be disabled."
================
Comment at: lib/CodeGen/CGExpr.cpp:357
+ unsigned AddrSpace =
+ CGF.getTarget().getTargetConstantAddressSpace().getValueOr(0);
auto *GV = new llvm::GlobalVariable(
----------------
This isn't the right logic. Part of what I was saying before is that this
optimization isn't obviously supportable on all targets. You should call
getTargetConstantAddressSpace() and then only try to do this optimization if it
doesn't return None.
For parity, the default implementation should return 0.
================
Comment at: lib/CodeGen/CGExpr.cpp:449
+ Var, ConvertTypeForMem(E->getType())->getPointerTo()),
Object.getAlignment());
// If the temporary is a global and has a constant initializer or is a
----------------
Every time you're tempted to use getPointerCast, you should instead be using
the target hook to lift the pointer into the right address space.
https://reviews.llvm.org/D33842
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