[llvm] [RISCV]Add support for resolving encoding conflicts among vendor specific CSRs (PR #96174)

[Craig Topper via llvm-commits]

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@@ -0,0 +1,118 @@
+// RUN: llvm-tblgen -gen-searchable-tables -I %p/../../include %s | FileCheck %s
+
+include "llvm/TableGen/SearchableTable.td"
+
+class SysReg<string name, bits<12> op> {
+  string Name = name;
+  bits<12> Encoding = op;
+  code FeaturesRequired = [{ {} }];
+}
+
+def List1 : GenericTable {
+  let FilterClass = "SysReg";
+  let Fields = [
+     "Name", "Encoding", "FeaturesRequired",
+  ];
+
+  let PrimaryKey = [ "Encoding" ];
+  let PrimaryKeyName = "lookupSysRegByEncoding";
+  let PrimaryKeyReturnRange = true;
+}
+
+
+let FeaturesRequired = [{ {Feature1} }] in {
+def : SysReg<"csr1", 0x7C9>;
+}
+
+let FeaturesRequired = [{ {Feature2} }] in {
+def : SysReg<"csr2", 0x7C9>;
+}
+
+// CHECK: #ifdef GET_List1_DECL
+// CHECK-NEXT: std::pair<const SysReg *, const SysReg *>lookupSysRegByEncoding(uint16_t Encoding);
+// CHECK-NEXT: #endif
+
+// CHECK: #ifdef GET_List1_IMPL
+// CHECK-NEXT: constexpr SysReg List1[] = {
+// CHECK-NEXT:   { "csr1", 0x7C9,  {Feature1}  }, // 0
+// CHECK-NEXT:   { "csr2", 0x7C9,  {Feature2}  }, // 1
+// CHECK-NEXT:  };
+
+// CHECK: std::pair<const SysReg *, const SysReg *>lookupSysRegByEncoding(uint16_t Encoding) {
+// CHECK-NEXT:   SysReg Key;
+// CHECK-NEXT:   Key.Encoding = Encoding;
+// CHECK-NEXT:   auto Table = ArrayRef(List1);
+// CHECK-NEXT:   auto It = std::equal_range(Table.begin(), Table.end(), Key,
+// CHECK-NEXT:     [](const SysReg &LHS, const SysReg &RHS) {
+// CHECK-NEXT:       if (LHS.Encoding < RHS.Encoding)
+// CHECK-NEXT:         return true;
+// CHECK-NEXT:       if (LHS.Encoding > RHS.Encoding)
+// CHECK-NEXT:         return false;
+// CHECK-NEXT:       return false;
+// CHECK-NEXT:     });
+// CHECK:       auto Idx = It.first;
+// CHECK-NEXT:  if (Idx == Table.end() ||
+// CHECK-NEXT:      Key.Encoding != Idx->Encoding)
+// CHECK-NEXT:   return {nullptr, nullptr};
+
+// CHECK:   return It;
+// CHECK-NEXT: }
+// CHECK-NEXT: #endif
+
+def List2 : GenericTable {
+  let FilterClass = "SysReg";
+  let Fields = [
+     "Name", "Encoding", "FeaturesRequired",
+  ];
+}
+
+def lookupSysRegByName : SearchIndex {
+  let Table = List2;
+  let Key = [ "Name" ];
+  let ReturnRange = true;
+}
+
+// CHECK: #ifdef GET_List2_DECL
+// CHECK-NEXT: std::pair<const SysReg *, const SysReg *>lookupSysRegByName(StringRef Name);
+// CHECK-NEXT: #endif
+
+// CHECK: #ifdef GET_List2_IMPL
+// CHECK-NEXT: constexpr SysReg List2[] = {
+// CHECK-NEXT:   { "csr1", 0x7C9,  {Feature1}  }, // 0
+// CHECK-NEXT:   { "csr2", 0x7C9,  {Feature2}  }, // 1
+// CHECK-NEXT:  };
+
+// CHECK: std::pair<const SysReg *, const SysReg *>lookupSysRegByName(StringRef Name) {
+// CHECK-NEXT:   struct IndexType {
+// CHECK-NEXT:     const char * Name;
+// CHECK-NEXT:     unsigned _index;
+// CHECK-NEXT:   };
+// CHECK-NEXT:   static const struct IndexType Index[] = {
+// CHECK-NEXT:     { "CSR1", 0 },
+// CHECK-NEXT:     { "CSR2", 1 },
+// CHECK-NEXT:   };
+
+// CHECK:   IndexType Key;
+// CHECK-NEXT:   Key.Name = Name.upper();
+// CHECK-NEXT:   auto Table = ArrayRef(Index);
+// CHECK-NEXT:   auto It = std::equal_range(Table.begin(), Table.end(), Key,
+// CHECK-NEXT:     [](const IndexType &LHS, const IndexType &RHS) {
+// CHECK-NEXT:       int CmpName = StringRef(LHS.Name).compare(RHS.Name);
+// CHECK-NEXT:       if (CmpName < 0) return true;
+// CHECK-NEXT:       if (CmpName > 0) return false;
+// CHECK-NEXT:       return false;
+// CHECK-NEXT:     });
+
+// CHECK:       auto Idx = It.first;
+// CHECK-NEXT:  if (Idx == Table.end() ||
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topperc wrote:

Is this needed? If there are no values in the table that contain the value we're looking for, then both iterators will end up the same, making an empty range.

https://github.com/llvm/llvm-project/pull/96174