[llvm] [AIX] Support per global code model. (PR #79202)

[Sean Fertile via llvm-commits]

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@@ -176,6 +176,15 @@ bool PPCSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const {
   // Large code model always uses the TOC even for local symbols.
   if (TM.getCodeModel() == CodeModel::Large)
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mandlebug wrote:

This was a really good question. I think originally I added this because it was triggering an assertion in the PPCAsmPrinter when we would emit the large code model nodes when the module code model was small. In reality both small and large code model use an indirect. That is true for both XCOFF and ELF - ELF has medium code model where we accessing things toc-relative instead of got indirect. I changed the AIX code to check for the toc-data attribute, since that is the only time a symbol would not be indirected on AIX. 

The existing code is slightly wrong in that we should be returning true for both small and large code model, but because of where (and how) this function is used that change will be untestable. We can update it in a separate NFC patch to make it correct at least, and when we add support for per global code model for ELF then it would be come testable.

https://github.com/llvm/llvm-project/pull/79202