[Instrumentor] Add counter IDs #16
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Both internally and externally we instrument code all the time. Usually, those are hand written traversals that look for some specific instructions or program points and then provide information to a runtime. Since the real difference is in the runtime, and the instrumentation is basically always the same, people can use this Instrumentor pass and configure it to their needs. Initial implementation only instruments alloca instructions but shows the setup, and configurability via a JSON file.
Following the alloca example, this adds store instruction instrumentation support. The following properties are captured: ``` void __instrumentor_store_pre(void* PointerOperand, int32_t PointerOperandAddressSpace, int64_t ValueOperand, int64_t ValueOperandSize, int32_t ValueOperandTypeId, int64_t Alignment, int32_t AtomicityOrdering, int8_t SyncScopeId, int8_t IsVolatile); void __instrumentor_store_pre_ind(void* PointerOperand, int32_t PointerOperandAddressSpace, void* ValueOperandStorage, int64_t ValueOperandSize, int32_t ValueOperandTypeId, int64_t Alignment, int32_t AtomicityOrdering, int8_t SyncScopeId, int8_t IsVolatile); ```
Following the store example, this adds load instruction instrumentation support. The following properties are captured: ``` void __instrumentor_pre_load(void* PointerOperand, int32_t PointerOperandAddressSpace, int64_t ValueSize, int32_t ValueTypeId, int64_t Alignment, int32_t AtomicityOrdering, int8_t SyncScopeId, int8_t IsVolatile); int64_t __instrumentor_post_load(void* PointerOperand, int32_t PointerOperandAddressSpace, int64_t Value, int64_t ValueSize, int32_t ValueTypeId, int64_t Alignment, int32_t AtomicityOrdering, int8_t SyncScopeId, int8_t IsVolatile); void __instrumentor_post_load_ind(void* PointerOperand, int32_t PointerOperandAddressSpace, void* ValueStorage, int64_t ValueSize, int32_t ValueTypeId, int64_t Alignment, int32_t AtomicityOrdering, int8_t SyncScopeId, int8_t IsVolatile); ```
This adds allocation call instrumentation support by exposing more of the memory builtin information, notably, non constant information. The following properties are captured: ``` void __instrumentor_post_allocation_call(void* MemoryPointer, int64_t MemorySize, int32_t Alignment, void /*char*/ * Family, int8_t InitialValue); void* __instrumentor_post_allocation_call(void* MemoryPointer, int64_t MemorySize, int32_t Alignment, void /*char*/ * Family, int8_t InitialValue); ```
Passing the arguments -Xclang -finstrumentor enables the instrumentor pass when compiling with Clang.
Features and optimizations: - Instrumentation of call arguments (pointers) - Instrumentation of base pointers - Instrumentation of globals - Skip loads and stores that are known to be safe at compile time - Passing base pointer info to load and store instrumentation calls
The arguments of the main function instrumentation are both pointers. We call the instrumentation function passing the pointers to the argc and argv arguments, so the instrumentation implementation can modify them.
A instrumentor database file contains the names of the functions and global variables that have been instrumented for a particular LLVM module. The database file is named as "<module-name>.instrdb". The -mllvm -instrumentor-read-database-dir=DIR allows loading the database files of other instrumented modules that are stored in the directory DIR. The -mllvm -instrumentor-write-database-dir=DIR allows writing the instrumented functions and globals from the current module in a database file in the directory DIR. If these flags are not specified, no database is read or written.
The call instrumentation was not working properly for globals and accesses that were marked as compile-time safe (e.g., constant offset on a alloca). This commit fixes that and removes the need for annotations. The option OnlyReplacedPointerValues in the call instrumentation is an optimzation to avoid passing non-pointer arguments and pointer arguments that were not replaced by another runtime call. This is very useful for the use case of the address sanitizer.
The reuse of temporary allocas for runtime calls did not consider when a call can use more than one alloca with the same total size. In that case, both were trying to use the same allocas, producing invalid IR. Now, we allow more than one alloca for each size. Each RTArgumentPack holds the temporary allocas that are used for a particular runtime call. Once the object is destroyed, these allocas are returned for reuse.
The OperandValueSize parameter is the number of bytes being stored instead of the number of bits.
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This pull request introduces the
add_call_countersbase configuration option. When enabled, this option will add an ID parameter to the end of each instrumentor function. Each instrumentation opportunity will have its own unique ID associated with it.