[llvm] [PEI][PowerPC] Fix false alarm of stack size limit (PR #65559)

[Nick Desaulniers via llvm-commits]

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@@ -2740,3 +2740,11 @@ bool PPCFrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
     return false;
   return !MF.getSubtarget<PPCSubtarget>().is32BitELFABI();
 }
+
+uint64_t PPCFrameLowering::getStackThreshold() const {
+  // The scratch register of STUX contains a signed negative 64-bit number.
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nickdesaulniers wrote:

I'm not very familiar with ppc, but this comment doesn't mean much to me. Maybe other reviewers with more familiarity can triple check it?

https://github.com/llvm/llvm-project/pull/65559