qiucf added a comment.
In D109950#3101740 <https://reviews.llvm.org/D109950#3101740>, @rjmccall wrote:
> Thanks. @hubert.reinterpretcast, @qiucf, can you verify that other compilers
> for PPC follow the logic for `TF` / `TC` that we now have with Elizabeth's
> patch? There are three different type specifiers (`long double`, `__ibm128`,
> and `float128_t`) which represent formally distinct types, and IIUC there are
> a bunch of different flags and target options that change the meaning of
> `long double` and/or disable/enable `__ibm128` and `float128_t`. We care
> about exactly which type is produced by the mode attribute, so you'll have to
> do something which is sensitive to the exact formal type, like `_Generic` or
> a C++ template or doing a pointer conversion without a cast; checking code
> generation will only tell us the underlying format.
typedef float __attribute__((mode(TF))) __tf128;
typedef float __attribute__((mode(IF))) __if128;
void foo() { printf(__func__); }
void bar() { printf(__func__); }
#define TEST(x) _Generic(x, __ibm128: foo, default: bar)()
int main() {
__if128 x;
__tf128 y;
TEST(x);
TEST(y);
}
// GCC (long double=ieee): foobar
// GCC (long double=ibm): foofoo
// Clang (both): foobar
As discussed in https://reviews.llvm.org/D93377#inline-874356 , GCC and Clang
handles them differently: in GCC `__ibm128` or `__float128` is alias to `long
double` under appropriate option, but Clang sees them as different types. While
for explicit mode, Clang thinks `float __attribute__((mode(IF)))` and
`__ibm128` are the same type. The patch doesn't change the behavior.
By the way, for x86 `__complex128 check(__complex128 a, __complex128 b) {
return a+b; }`, GCC seems to generate two `___addtf3`, while Clang generates
`faddp`.
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https://reviews.llvm.org/D109950/new/
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