[llvm] [AMDGPU][MC] Allow UC_VERSION_* constant reuse (PR #96461)

[Ivan Kosarev via llvm-commits]

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@@ -1755,18 +1755,25 @@ MCOperand AMDGPUDisassembler::decodeVersionImm(unsigned Imm) const {
   if (Encoding::encode(Version, W64, W32, MDP) != Imm)
     return MCOperand::createImm(Imm);
 
-  const auto &Versions = AMDGPU::UCVersion::getGFXVersions();
-  auto I = find_if(Versions,
-                   [Version = Version](const AMDGPU::UCVersion::GFXVersion &V) {
-                     return V.Code == Version;
-                   });
+  // Locate UC_VERSION symbol matching Version.
   MCContext &Ctx = getContext();
-  const MCExpr *E;
-  if (I == Versions.end())
+  const MCExpr *E = nullptr;
+  for (auto *VersionSym : UCVersionSymbols) {
+    int64_t Val;
+    if (!VersionSym->evaluateAsAbsolute(Val))
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kosarev wrote:

Doing `evaluateAsAbsolute()` here doesn't prevent the symbols from being redefined later, so looks an unnecessary complication.

A proper solution would involve supporting constant symbols. Until then it seems whatever we do, it won't help us where any of the symbols get redefined.

https://github.com/llvm/llvm-project/pull/96461