MaskRay added inline comments.
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:13317
+ continue;
+ Value *Idxs[] = {Builder.getInt32(0), Builder.getInt32(i - 1)};
+ Value *Features = Builder.CreateAlignedLoad(
----------------
FreddyYe wrote:
> Don't quite understand why we need to change from a i32* into <4 x i32>* and
> the first element here to be always zero.
Sorry, this global variable (array) should be <3 x i32>. Fixed.
This (strange) scheme is for GCC/libgcc compatibility: bits 0~31 are in
`__cpu_model.__cpufeatures[0]` while bits 32~max are in `__cpu_features2[0..2]`
================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:13319
+ Value *Features = Builder.CreateAlignedLoad(
+ Int32Ty, Builder.CreateGEP(ATy, CpuFeatures2, Idxs),
+ CharUnits::fromQuantity(4));
----------------
FreddyYe wrote:
> Will function multi version also be fixed in this patch?
> https://gcc.godbolt.org/z/cafhs9qbG If so, need to add test in
> clang/test/CodeGen/attr-target-mv.c
The `target` attribute has strange semantics for overloading:
```
int __attribute__((target("arch=skylake"))) foo(void) {return 0;}
int __attribute__((target("arch=x86-64"))) foo(void) {return 1;}
```
is not allowed in C mode of GCC.
I think such use cases are not recommended in C++.
If we don't use overloading, `int __attribute__((target("arch=x86-64")))
foo(void) {return 1;}` is supported by Clang today and this patch does not
intend to change anything about it.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D158329/new/
https://reviews.llvm.org/D158329
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