Log helper functions of all Call instructions

Summary:
We want to log C helper function usage using a new flag `-X jit-dump-c-helper`. We will log the memory address of every `Call`, `VectorCall`, `Invoke` instruction that is processed in the `Cinder/Jit/lir/block_builder/AppendCodeLine` function. If the memory address can be resolved into a name, then the function name will be logged instead.

This change involves setting up a new logging flag ( `Cinder/Jit/log.h`, `Cinder/Jit/pyjit.cpp`) and adding logging logic to  `Cinder/Jit/lir/block_builder.cpp` .

Reviewed By: swtaarrs

Differential Revision: D28691583

fbshipit-source-id: 234bc89

Jit/lir/block_builder.cpp

@@ -4,6 +4,8 @@
 #include "Jit/lir/lir.h"
 #include "Jit/util.h"
 
+#include <dlfcn.h>
+
 // XXX: this file needs to be revisited when we optimize HIR-to-LIR translation
 // in codegen.cpp/h. Currently, this file is almost an identical copy from
 // bbbuilder.cpp with some interfaces changes so that it works with the new
@@ -273,6 +275,21 @@ void BasicBlockBuilder::AppendCodeLine(const std::string& s) {
     bool is_invoke = (instr_str == "Invoke");
     bool is_vector_call = (instr_str == "Vectorcall");
 
+    if (g_dump_c_helper) {
+      size_t dest_idx = is_invoke ? 1 : 2;
+      if (dest_idx < tokens.size() && IsConstant(tokens[dest_idx])) {
+        std::string helper_id = GetId(tokens[dest_idx]);
+        uint64_t helper_addr = stoull(helper_id);
+        Dl_info helper_info;
+        if (dladdr(reinterpret_cast<void*>(helper_addr), &helper_info) != 0 &&
+            helper_info.dli_sname != NULL) {
+          JIT_LOG("Call to function %s.", helper_info.dli_sname);
+        } else {
+          JIT_LOG("Call to function at %s.", tokens[dest_idx]);
+        }
+      }
+    }
+
     auto instr = createInstr(
         is_vector_call ? Instruction::kVectorCall : Instruction::kCall);
 

Jit/log.cpp

@@ -12,6 +12,7 @@ int g_dump_hir_passes = 0;
 int g_dump_final_hir = 0;
 int g_dump_lir = 0;
 int g_dump_lir_no_origin = 0;
+int g_dump_c_helper = 0;
 int g_disas_funcs = 0;
 int g_dump_stats = 0;
 FILE* g_log_file = stderr;

Jit/log.h

@@ -29,6 +29,7 @@ extern int g_dump_hir_passes;
 extern int g_dump_final_hir;
 extern int g_dump_lir;
 extern int g_dump_lir_no_origin;
+extern int g_dump_c_helper;
 extern int g_disas_funcs;
 extern int g_dump_stats;
 extern FILE* g_log_file;

Jit/pyjit.cpp

@@ -751,6 +751,10 @@ int _PyJIT_Initialize() {
     g_dump_lir = 1;
     g_dump_lir_no_origin = 1;
   }
+  if (_is_flag_set("jit-dump-c-helper", "PYTHONJITDUMPCHELPER")) {
+    JIT_DLOG("Enable JIT dump-c-helper mode.");
+    g_dump_c_helper = 1;
+  }
   if (_is_flag_set("jit-disas-funcs", "PYTHONJITDISASFUNCS")) {
     JIT_DLOG("Enabling JIT disas-funcs mode.");
     g_disas_funcs = 1;