Merge commit c80c09f3e380 from llvm-project (by Dimitry Andric):
[CalcSpillWeights] Avoid x87 excess precision influencing weight result Fixes #99396 The result of `VirtRegAuxInfo::weightCalcHelper` can be influenced by x87 excess precision, which can result in slightly different register choices when the compiler is hosted on x86_64 or i386. This leads to different object file output when cross-compiling to i386, or native. Similar to 7af3432e22b0, we need to add a `volatile` qualifier to the local `Weight` variable to force it onto the stack, and avoid the excess precision. Define `stack_float_t` in `MathExtras.h` for this purpose, and use it.
This is the version of the fix for PR276961 that landed upstream.
PR: 276961
Reported by: cperciva
MFC after: 3 days
(cherry picked from commit 1a4b8325f6e3a45c77188343da504fe04495cc46)