[Analysis] Move TargetLibraryInfo data to TableGen (llvm#165009)

The collection of library function names in TargetLibraryInfo faces
similar challenges as RuntimeLibCalls in the IR component. The number of
function names is large, there are numerous customizations based on the
triple (including alternate names), and there is a lot of replicated
data in the signature table.

The ultimate goal would be to capture all lbrary function related
information in a .td file. This PR brings the current .def file to
TableGen, almost as a 1:1 replacement. However, there are some
improvements which are not possible in the current implementation:

- the function names are now stored as a long string together with an
offset table.
- the table of signatures is now deduplicated, using an offset table for
access.

The size of the object file decreases about 34kB with these changes. The
hash table of all function names is still constructed dynamically. A
static table like for RuntimeLibCalls is the next logical step.

The main motivation for this change is that I have to add a large number
of custom names for z/OS (like in RuntimeLibCalls.td), and the current
infrastructur does not support this very well.

Author: redstar

llvm/include/llvm/Analysis/CMakeLists.txt

@@ -0,0 +1,3 @@
+set(LLVM_TARGET_DEFINITIONS TargetLibraryInfo.td)
+tablegen(LLVM TargetLibraryInfo.inc -gen-target-library-info)
+add_public_tablegen_target(analysis_gen)

llvm/include/llvm/Analysis/TargetLibraryInfo.def

@@ -10,6 +10,7 @@
 #define LLVM_ANALYSIS_TARGETLIBRARYINFO_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringTable.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Module.h"
@@ -70,13 +71,8 @@ class VecDesc {
   LLVM_ABI std::string getVectorFunctionABIVariantString() const;
 };
 
-  enum LibFunc : unsigned {
-#define TLI_DEFINE_ENUM
-#include "llvm/Analysis/TargetLibraryInfo.def"
-
-    NumLibFuncs,
-    NotLibFunc
-  };
+#define GET_TARGET_LIBRARY_INFO_ENUM
+#include "llvm/Analysis/TargetLibraryInfo.inc"
 
 /// Implementation of the target library information.
 ///
@@ -89,7 +85,8 @@ class TargetLibraryInfoImpl {
 
   unsigned char AvailableArray[(NumLibFuncs+3)/4];
   DenseMap<unsigned, std::string> CustomNames;
-  LLVM_ABI static StringLiteral const StandardNames[NumLibFuncs];
+#define GET_TARGET_LIBRARY_INFO_IMPL_DECL
+#include "llvm/Analysis/TargetLibraryInfo.inc"
   bool ShouldExtI32Param, ShouldExtI32Return, ShouldSignExtI32Param, ShouldSignExtI32Return;
   unsigned SizeOfInt;
 
@@ -160,7 +157,8 @@ class TargetLibraryInfoImpl {
   /// Forces a function to be marked as available and provide an alternate name
   /// that must be used.
   void setAvailableWithName(LibFunc F, StringRef Name) {
-    if (StandardNames[F] != Name) {
+    if (StringRef(StandardNamesStrTable.getCString(StandardNamesOffsets[F]),
+                  StandardNamesSizeTable[F]) != Name) {
       setState(F, CustomName);
       CustomNames[F] = std::string(Name);
       assert(CustomNames.contains(F));
@@ -438,15 +436,19 @@ class TargetLibraryInfo {
   /// Return the canonical name for a LibFunc. This should not be used for
   /// semantic purposes, use getName instead.
   static StringRef getStandardName(LibFunc F) {
-    return TargetLibraryInfoImpl::StandardNames[F];
+    return StringRef(TargetLibraryInfoImpl::StandardNamesStrTable.getCString(
+                         TargetLibraryInfoImpl::StandardNamesOffsets[F]),
+                     TargetLibraryInfoImpl::StandardNamesSizeTable[F]);
   }
 
   StringRef getName(LibFunc F) const {
     auto State = getState(F);
     if (State == TargetLibraryInfoImpl::Unavailable)
       return StringRef();
     if (State == TargetLibraryInfoImpl::StandardName)
-      return Impl->StandardNames[F];
+      return StringRef(
+          Impl->StandardNamesStrTable.getCString(Impl->StandardNamesOffsets[F]),
+          Impl->StandardNamesSizeTable[F]);
     assert(State == TargetLibraryInfoImpl::CustomName);
     return Impl->CustomNames.find(F)->second;
   }