hexagon: use a single global_asm! block for source-order stability

[androm3da]

Since rust-lang/rust#145358 ("Sort mono items by symbol name", merged 2025-08-22), rustc sorts mono items within a codegen unit by symbol name rather than source order unless -Zcodegen-source-order is passed.

That breaks func_macro.s, which defines asm macros for use by "later" files.

Merge all includes into one global_asm! call. A single MonoItem cannot be reordered against itself, so the source order becomes the order the assembler sees. The file set and its order are unchanged, and all these items already shared one codegen unit, so object-file granularity is unaffected.

Closes: #1240

[androm3da]

Fixes #1240

[tgross35]

LGTM, thanks. Looks like that PR merged almost a year ago, any idea why there wasn't any problem until now?

View changes since this review

[bjorn3]

Be aware that macros are technically not allowed in global_asm!(). They are not on the list of allowed directives at https://doc.rust-lang.org/reference/inline-assembly.html#directives-support and for every stateful directive (which includes macros) you have to undo their effect before exitting the global_asm!() block. So at the very least you did have to use .push_section/.pop_section rather than .text and undefine all macros at the end (is that last one even possible?).

[androm3da]

Be aware that macros are technically not allowed in global_asm!(). They are not on the list of allowed directives at https://doc.rust-lang.org/reference/inline-assembly.html#directives-support and for every stateful directive (which includes macros) you have to undo their effect before exitting the global_asm!() block. So at the very least you did have to use .push_section/.pop_section rather than .text and undefine all macros at the end (is that last one even possible?).

Okay - good point. I liked having the asm here resemble the corresponding stuff in compiler-rt. But I'm fine w/remediating this by fixing the asm to no longer depend on the .macro directive.

[androm3da]

LGTM, thanks. Looks like that PR merged almost a year ago, any idea why there wasn't any problem until now?

Sadly, we have not done a good enough job maintaining the hexagon targets. 😖

[bjorn3]

You still want to avoid code duplication you could use a rust macro that you invoke inside the global_asm!(). Something like global_asm!(function_begin!("foo"), "contents", function_end!("foo"), function_begin!("bar"), "contents2", function_end!("foo")) or global_asm!(function!("foo", "contents"), function!("bar", "contents2")). If you do it that way, you can probably split them into separate global_asm!() blocks again if you want.