[llvm] MCExpr-ify SIProgramInfo (PR #88257)

[Pierre van Houtryve via llvm-commits]

================
@@ -86,6 +105,158 @@ bool AMDGPUVariadicMCExpr::evaluateAsRelocatableImpl(
     MCValue &Res, const MCAsmLayout *Layout, const MCFixup *Fixup) const {
   std::optional<int64_t> Total;
 
+  auto TryGetMCExprValue = [&](const MCExpr *Arg, uint64_t &ConstantValue) {
+    MCValue MCVal;
+    if (!Arg->evaluateAsRelocatable(MCVal, Layout, Fixup) ||
+        !MCVal.isAbsolute())
+      return false;
+
+    ConstantValue = MCVal.getConstant();
+    return true;
+  };
+
+  if (Kind == AGVK_ExtraSGPRs) {
+    assert(Args.size() == 5 &&
+           "AMDGPUVariadic Argument count incorrect for ExtraSGPRs");
+    uint64_t VCCUsed, FlatScrUsed, MajorVersion, XNACKUsed,
+        hasArchitectedFlatScr, ExtraSGPRs = 0;
+
+    bool Success = true;
+    Success &= TryGetMCExprValue(Args[0], MajorVersion);
----------------
Pierre-vh wrote:

```suggestion
    bool Success = TryGetMCExprValue(Args[0], MajorVersion) 
```

https://github.com/llvm/llvm-project/pull/88257