[llvm] Add Apple M4 host detection (PR #117530)

[Jon Roelofs via llvm-commits]

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@@ -1494,15 +1539,24 @@ StringRef sys::getHostCPUName() {
     return "apple-a12";
   case CPUFAMILY_ARM_LIGHTNING_THUNDER:
     return "apple-a13";
-  case CPUFAMILY_ARM_FIRESTORM_ICESTORM:
+  case CPUFAMILY_ARM_FIRESTORM_ICESTORM: // A14 / M1
     return "apple-m1";
-  case CPUFAMILY_ARM_BLIZZARD_AVALANCHE:
+  case CPUFAMILY_ARM_BLIZZARD_AVALANCHE: // A15 / M2
     return "apple-m2";
-  case CPUFAMILY_ARM_EVEREST_SAWTOOTH:
+  case CPUFAMILY_ARM_EVEREST_SAWTOOTH: // A16
+  case CPUFAMILY_ARM_IBIZA:            // M3
+  case CPUFAMILY_ARM_PALMA:            // M3 Max
+  case CPUFAMILY_ARM_COLL:             // A17
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jroelofs wrote:

Wikipedia isn't a reliable source for this at all. Those pages often quote llvm's tablegen files as a source of truth on things, which sometimes aren't precisely correct for various reasons, both upstream-visible, and sometimes not-upstream-visible ones that I'm not going to explain here. We have them as separate processor definitions in `AArch64Processors.td` for _reasons_, and as lame of a justification that is, this code should respect that.... please.

https://github.com/llvm/llvm-project/pull/117530