rjmccall added inline comments.
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:2090-2094
+ // Variadic functions expect the caller to promote float to double.
+ if (CanonicalType == Context.FloatTy) {
+ FieldPtr =
+ CGF.Builder.CreateFPExt(FieldPtr, CGF.ConvertType(Context.DoubleTy));
+ }
----------------
aaron.ballman wrote:
> This change is an improvement as far as it goes, but I think we might be
> missing other floating-point promotions here. For example, `__fp16` fields
> also seem to be unusable: https://godbolt.org/z/z3a45f9YE
>
> Also, we don't seem to handle the integer promotions at all (but still get
> correct results there), so I think we're getting the correct behavior there
> by chance rather than by design. Oh, yeah, note the differences here:
> https://godbolt.org/z/f13eq3668
>
> ```
> foo:
> ...
> %7 = load i8, i8* %4, align 1, !dbg !217
> %8 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([6 x i8], [6 x
> i8]* @2, i32 0, i32 0), i8 %7), !dbg !217
> ...
>
> bar:
> ...
> %2 = load i8, i8* %1, align 1, !dbg !222
> %3 = zext i8 %2 to i32, !dbg !222
> %4 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x i8], [5 x
> i8]* @.str, i64 0, i64 0), i32 %3), !dbg !223
> ...
> ```
> I think we should probably fix all of the promotion problems at once rather
> than piecemeal.
>
It's actually really annoying that this logic has to be duplicated in IRGen
instead of being able to take advantage of the existing promotion logic in
Sema. Can we just generate a helper function in Sema and somehow link it to
the builtin call?
Um. Also, the `static` local DenseMap in the code above this is totally
unacceptable and should not have been committed. Clang is supposed to be
embeddable as a library and should not be using global mutable variables.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D112626/new/
https://reviews.llvm.org/D112626
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