aaron.ballman added a reviewer: paulsemel.
aaron.ballman added a subscriber: paulsemel.
aaron.ballman added a comment.
Adding @paulsemel to the reviewer list as he was the original author of this
functionality (I commit on his behalf which is how I showed up on the git
blame).
================
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));
+ }
----------------
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.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D112626/new/
https://reviews.llvm.org/D112626
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