The previous version (ported from musl) used bit-by-bit calculations and was slow, but the current version (also ported from musl) uses lookup tables combined with Goldschmidt iterations to significantly improve the speed.
FreeBSD normally provides this symbol in libc, but it's in the
FBSDprivate_1.0 namespace, so it doesn't get included in our abilists file.
Fortunately, the implementation is identical for Linux and FreeBSD, so we can
just provide it in compiler-rt.
It's interesting to note that the same is not true for NetBSD where the
implementation is more complex to support older Arm versions. But we do include
the symbol in our abilists file for NetBSD libc, so that's fine.
closes#25215
LLVM 21 has started recognizing strlen-like idioms and optimizing them to strlen
calls, so we need this function provided in compiler-rt for libc-less
compilations.
The big endian RISC-V effort is mostly driven by MIPS (the company) which is
pivoting to RISC-V, and presumably needs a big endian variant to fill the niche
that big endian MIPS (the ISA) did.
GCC already supports these targets, but LLVM support will only appear in 22;
this commit just adds the necessary target knowledge and checks on our end.
This is not meant to be a long-term solution, but it's the easiest thing
to get working quickly at the moment. The main intention of this hack is
to allow more tests to be enabled. By the time the coff linker is far
enough along to be enabled by default, this will no longer be required.
If you write an if expression in mem.doNotOptimizeAway like
doNotOptimizeAway(if (ix < 0x00100000) x / 0x1p120 else x + 0x1p120);,
FCSEL instruction is used on AArch64.
FCSEL instruction selects one of the two registers according to
the condition and copies its value.
In this example, `x / 0x1p120` and `x + 0x1p120` are expressions
that raise different floating-point exceptions.
However, since both are actually evaluated before the FCSEL
instruction, the exception not intended by the programmer may
also be raised.
To prevent FCSEL instruction from being used here, this commit
splits doNotOptimizeAway in two.
This prevents symbols from these libraries from polluting the dynamic symbol
tables of binaries built with Zig. The downside is that we no longer deduplicate
the symbols at run time due to weak linkage.
Closes#7935.
Closes#13303.
Closes#19342.
Functions like isMinGW() and isGnuLibC() have a good reason to exist: They look
at multiple components of the target. But functions like isWasm(), isDarwin(),
isGnu(), etc only exist to save 4-8 characters. I don't think this is a good
enough reason to keep them, especially given that:
* It's not immediately obvious to a reader whether target.isDarwin() means the
same thing as target.os.tag.isDarwin() precisely because isMinGW() and similar
functions *do* look at multiple components.
* It's not clear where we would draw the line. The logical conclusion before
this commit would be to also wrap Arch.isX86(), Os.Tag.isSolarish(),
Abi.isOpenHarmony(), etc... this obviously quickly gets out of hand.
* It's nice to just have a single correct way of doing something.
