[llvm] [LLVM][TableGen] Decrease code size of `getAttributes` (PR #110573)

[Rahul Joshi via llvm-commits]

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@@ -576,75 +582,79 @@ static AttributeSet getIntrinsicFnAttributeSet(LLVMContext &C, unsigned ID) {
 AttributeList Intrinsic::getAttributes(LLVMContext &C, ID id) {
 )";
 
-  // Compute the maximum number of attribute arguments and the map.
-  typedef std::map<const CodeGenIntrinsic *, unsigned, AttributeComparator>
-      UniqAttrMapTy;
-  UniqAttrMapTy UniqAttributes;
-  unsigned MaxArgAttrs = 0;
-  unsigned AttrNum = 0;
+  // Compute the maximum number of attribute arguments and the map. For function
+  // attributes, we only consider whether the intrinsics has any function
+  // arguments or not.
+  std::map<const CodeGenIntrinsic *, unsigned, AttributeComparator>
+      UniqAttributes;
   for (const CodeGenIntrinsic &Int : Ints) {
-    MaxArgAttrs =
-        std::max(MaxArgAttrs, unsigned(Int.ArgumentAttributes.size()));
-    unsigned &N = UniqAttributes[&Int];
-    if (N)
-      continue;
-    N = ++AttrNum;
-    assert(N < 65536 && "Too many unique attributes for table!");
+    unsigned ID = UniqAttributes.size();
+    UniqAttributes.try_emplace(&Int, ID);
   }
 
+  // Assign a 16-bit packed ID for each intrinsic. The lower 8-bits will be its
+  // "argument attribute ID" (index in UniqAttributes) and upper 8 bits will be
+  // its "function attribute ID" (index in UniqFnAttributes).
+  assert(UniqAttributes.size() < 256 &&
+         "Too many unique argument attributes for table!");
+  assert(UniqFnAttributes.size() < 256 &&
+         "Too many unique function attributes for table!");
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jurahul wrote:

Done.

https://github.com/llvm/llvm-project/pull/110573