[llvm] 35e48d7 - [ORC] Add C API functions to obtain and clear the symbol string pool.

[Lang Hames via llvm-commits]

Author: Lang Hames
Date: 2020-10-19T01:59:03-07:00
New Revision: 35e48d7b91735136e423f71c1d7406eb07a03e89

URL: https://github.com/llvm/llvm-project/commit/35e48d7b91735136e423f71c1d7406eb07a03e89
DIFF: https://github.com/llvm/llvm-project/commit/35e48d7b91735136e423f71c1d7406eb07a03e89.diff

LOG: [ORC] Add C API functions to obtain and clear the symbol string pool.

Symbol string pool entries are ref counted, but not automatically cleared.
This can cause the size of the pool to grow without bound if it's not
periodically cleared. These functions allow that to be done via the C API.

Added: 
    

Modified: 
    llvm/include/llvm-c/Orc.h
    llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm-c/Orc.h b/llvm/include/llvm-c/Orc.h
index 50caae18e2d4..e80874629ff8 100644
--- a/llvm/include/llvm-c/Orc.h
+++ b/llvm/include/llvm-c/Orc.h
@@ -43,6 +43,11 @@ typedef uint64_t LLVMOrcJITTargetAddress;
  */
 typedef struct LLVMOrcOpaqueExecutionSession *LLVMOrcExecutionSessionRef;
 
+/**
+ * A reference to an orc::SymbolStringPool.
+ */
+typedef struct LLVMOrcOpaqueSymbolStringPool *LLVMOrcSymbolStringPoolRef;
+
 /**
  * A reference to an orc::SymbolStringPool table entry.
  */
@@ -110,6 +115,27 @@ void LLVMOrcExecutionSessionSetErrorReporter(
     LLVMOrcExecutionSessionRef ES, LLVMOrcErrorReporterFunction ReportError,
     void *Ctx);
 
+/**
+ * Return a reference to the SymbolStringPool for an ExecutionSession.
+ *
+ * Ownership of the pool remains with the ExecutionSession: The caller is
+ * not required to free the pool.
+ */
+LLVMOrcSymbolStringPoolRef
+LLVMOrcExecutionSessionGetSymbolStringPool(LLVMOrcExecutionSessionRef ES);
+
+/**
+ * Clear all unreferenced symbol string pool entries.
+ *
+ * This can be called at any time to release unused entries in the
+ * ExecutionSession's string pool. Since it locks the pool (preventing
+ * interning of any new strings) it is recommended that it only be called
+ * infrequently, ideally when the caller has reason to believe that some
+ * entries will have become unreferenced, e.g. after removing a module or
+ * closing a JITDylib.
+ */
+void LLVMOrcSymbolStringPoolClearDeadEntries(LLVMOrcSymbolStringPoolRef SSP);
+
 /**
  * Intern a string in the ExecutionSession's SymbolStringPool and return a
  * reference to it. This increments the ref-count of the pool entry, and the

diff  --git a/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp b/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
index 1179f677389f..91b90bcf78a3 100644
--- a/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
@@ -43,6 +43,7 @@ class OrcV2CAPIHelper {
 } // end namespace llvm
 
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ExecutionSession, LLVMOrcExecutionSessionRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(SymbolStringPool, LLVMOrcSymbolStringPoolRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(OrcV2CAPIHelper::PoolEntry,
                                    LLVMOrcSymbolStringPoolEntryRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(JITDylib, LLVMOrcJITDylibRef)
@@ -65,6 +66,15 @@ void LLVMOrcExecutionSessionSetErrorReporter(
       [=](Error Err) { ReportError(Ctx, wrap(std::move(Err))); });
 }
 
+LLVMOrcSymbolStringPoolRef
+LLVMOrcExecutionSessionGetSymbolStringPool(LLVMOrcExecutionSessionRef ES) {
+  return wrap(unwrap(ES)->getSymbolStringPool().get());
+}
+
+void LLVMOrcSymbolStringPoolClearDeadEntries(LLVMOrcSymbolStringPoolRef SSP) {
+  unwrap(SSP)->clearDeadEntries();
+}
+
 LLVMOrcSymbolStringPoolEntryRef
 LLVMOrcExecutionSessionIntern(LLVMOrcExecutionSessionRef ES, const char *Name) {
   return wrap(