rjmccall added inline comments.
================
Comment at: include/clang/AST/APValue.h:379
void setLValue(LValueBase B, const CharUnits &O, NoLValuePath,
- unsigned CallIndex);
+ unsigned CallIndex, bool IsNuppPtr);
void setLValue(LValueBase B, const CharUnits &O,
----------------
Typo.
================
Comment at: lib/AST/ExprConstant.cpp:1153
+ IsNullPtr = false;
+ }
+ void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E, uint64_t Index,
----------------
Hmm. I think the code would be clearer overall if this were conditionalized in
the callers instead of here.
================
Comment at: lib/CodeGen/CGExprScalar.cpp:1532
+ return llvm::ConstantInt::get(ConvertType(DestTy),
+ CGF.getContext().getTargetNullPtrValue(E->getType()));
assert(!DestTy->isBooleanType() && "bool should use PointerToBool");
----------------
yaxunl wrote:
> rjmccall wrote:
> > Why is this necessary? ptrtoint on the recursively-emitted null pointer
> > should do this automatically.
> Since the target knows the value in the null pointers, it can fold a null
> pointer to integer literal directly.
>
> The above code does that, e.g.
>
> ```
> void test_cast_null_pointer_to_sizet_calee(size_t arg_private,
> size_t arg_local,
> size_t arg_global,
> size_t arg_constant,
> size_t arg_generic);
>
> // CHECK-LABEL: test_cast_null_pointer_to_sizet
> // CHECK: call void @test_cast_null_pointer_to_sizet_calee(i64 -1, i64 -1,
> i64 0, i64 0, i64 0)
> void test_cast_null_pointer_to_sizet(void) {
> test_cast_null_pointer_to_sizet_calee((size_t)((private char*)0),
> (size_t)((local char*)0),
> (size_t)((global char*)0),
> (size_t)((constant char*)0),
> (size_t)((generic char*)0));
> }
>
> ```
>
> Without the above code, we only get ptrtoint instructions.
Oh, does the constant folder not know how to fold ptrtoint(inttoptr(X)) -> X?
I guess that's probably LLVM's nominal target-independence rearing its head.
Is getting a slightly LLVM constant actually important here? I would prefer to
avoid this complexity (and unnecessary recursive walk) if possible.
================
Comment at: lib/CodeGen/TargetInfo.h:236
+ virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF,
+ Expr *E, QualType DestTy) const;
+
----------------
This should just take a Value* and the source and dest types.
https://reviews.llvm.org/D26196
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