[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);
+    Success &= TryGetMCExprValue(Args[3], XNACKUsed);
+    Success &= TryGetMCExprValue(Args[4], hasArchitectedFlatScr);
+
+    assert(Success &&
+           "Arguments 1, 4, and 5 for ExtraSGPRs should be known constants");
+    if (!Success || !TryGetMCExprValue(Args[1], VCCUsed) ||
+        !TryGetMCExprValue(Args[2], FlatScrUsed))
+      return false;
+
+    if (VCCUsed)
+      ExtraSGPRs = 2;
+    if (MajorVersion >= 10) {
+      Res = MCValue::get(ExtraSGPRs);
+      return true;
+    }
+    if (MajorVersion < 8) {
+      if (FlatScrUsed)
+        ExtraSGPRs = 4;
+    } else {
+      if (XNACKUsed)
+        ExtraSGPRs = 4;
+      if (FlatScrUsed || hasArchitectedFlatScr)
+        ExtraSGPRs = 6;
+    }
+
+    Res = MCValue::get(ExtraSGPRs);
+    return true;
+  }
+
+  if (Kind == AGVK_AlignTo) {
+    assert(Args.size() == 2 &&
+           "AMDGPUVariadic Argument count incorrect for AlignTo");
+    uint64_t Value, Align;
+    if (!TryGetMCExprValue(Args[0], Value) ||
+        !TryGetMCExprValue(Args[1], Align))
+      return false;
+
+    Res = MCValue::get(alignTo(Value, Align));
+    return true;
+  }
+
+  if (Kind == AGVK_TotalNumVGPRs90A) {
+    assert(Args.size() == 2 &&
+           "AMDGPUVariadic Argument count incorrect for TotalNumVGPRs90A");
+    uint64_t NumAGPR, NumVGPR, Total;
+    if (!TryGetMCExprValue(Args[0], NumAGPR) ||
+        !TryGetMCExprValue(Args[1], NumVGPR))
+      return false;
+
+    if (NumAGPR) {
+      Total = alignTo(NumVGPR, 4) + NumAGPR;
+    } else {
+      Total = std::max(NumVGPR, NumAGPR);
+    }
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Pierre-vh wrote:

nit: can drop `{}` here or just use a ternary

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