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| author | Koki Ueha <jeamsblue@gmail.com> | 2025-06-15 01:05:58 +0000 |
|---|---|---|
| committer | Jacob Young <15544577+jacobly0@users.noreply.github.com> | 2025-06-15 04:01:43 -0400 |
| commit | 878b7b80c15d4b9a894f6ab1d4e8753de77568ad (patch) | |
| tree | db26c68ae9e0da28fefba8c0b2b2f917655bbbdb /lib/std/Build/Step/InstallFile.zig | |
| parent | 3ce8d19f76690afe21b77651cffef9a9866cbf30 (diff) | |
| download | zig-878b7b80c15d4b9a894f6ab1d4e8753de77568ad.tar.gz zig-878b7b80c15d4b9a894f6ab1d4e8753de77568ad.zip | |
libc: Prevent FCSEL instruction from being used to avoid raising an unintended exception
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.
Diffstat (limited to 'lib/std/Build/Step/InstallFile.zig')
0 files changed, 0 insertions, 0 deletions