[llvm] r271652 - [LPM] Replace the CALL_ONCE_... macro in the legacy pass manager with

Chandler Carruth via llvm-commits llvm-commits at lists.llvm.org
Fri Jun 3 03:20:03 PDT 2016


Author: chandlerc
Date: Fri Jun  3 05:20:02 2016
New Revision: 271652

URL: http://llvm.org/viewvc/llvm-project?rev=271652&view=rev
Log:
[LPM] Replace the CALL_ONCE_... macro in the legacy pass manager with
the new llvm::call_once facility.

This facility matches the standard APIs and when the platform supports
it actually directly uses the standard provided functionality. This is
both more efficient on some platforms and much more TSan friendly.

The only remaining user of the cas_flag and home-rolled atomics is the
fallback implementation of call_once. I have a patch that removes them
entirely, but it needs a Windows patch to land first.

This alone substantially cleans up the macros for the legacy pass
manager, and should subsume some of the work Mehdi was doing to clear
the path for TSan testing of ThinLTO, a really important step to have
reliable upstream testing of ThinLTO in all forms.

Modified:
    llvm/trunk/include/llvm/CodeGen/Passes.h
    llvm/trunk/include/llvm/PassSupport.h

Modified: llvm/trunk/include/llvm/CodeGen/Passes.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/Passes.h?rev=271652&r1=271651&r2=271652&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/Passes.h (original)
+++ llvm/trunk/include/llvm/CodeGen/Passes.h Fri Jun  3 05:20:02 2016
@@ -377,8 +377,10 @@ namespace llvm {
   Registry.registerPass(*PI, true);                                            \
   return PI;                                                                   \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
-    CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce)                   \
+    call_once(Initialize##passName##PassFlag, initialize##passName##PassOnce,  \
+              std::ref(Registry));                                             \
   }
 
 /// This initializer registers TargetMachine constructor, so the pass being

Modified: llvm/trunk/include/llvm/PassSupport.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/PassSupport.h?rev=271652&r1=271651&r2=271652&view=diff
==============================================================================
--- llvm/trunk/include/llvm/PassSupport.h (original)
+++ llvm/trunk/include/llvm/PassSupport.h Fri Jun  3 05:20:02 2016
@@ -26,31 +26,13 @@
 #include "llvm/PassInfo.h"
 #include "llvm/PassRegistry.h"
 #include "llvm/Support/Atomic.h"
+#include "llvm/Support/Threading.h"
+#include <functional>
 
 namespace llvm {
 
 class TargetMachine;
 
-#define CALL_ONCE_INITIALIZATION(function)                                     \
-  static volatile sys::cas_flag initialized = 0;                               \
-  sys::cas_flag old_val = sys::CompareAndSwap(&initialized, 1, 0);             \
-  if (old_val == 0) {                                                          \
-    function(Registry);                                                        \
-    sys::MemoryFence();                                                        \
-    TsanIgnoreWritesBegin();                                                   \
-    TsanHappensBefore(&initialized);                                           \
-    initialized = 2;                                                           \
-    TsanIgnoreWritesEnd();                                                     \
-  } else {                                                                     \
-    sys::cas_flag tmp = initialized;                                           \
-    sys::MemoryFence();                                                        \
-    while (tmp != 2) {                                                         \
-      tmp = initialized;                                                       \
-      sys::MemoryFence();                                                      \
-    }                                                                          \
-  }                                                                            \
-  TsanHappensAfter(&initialized);
-
 #define INITIALIZE_PASS(passName, arg, name, cfg, analysis)                    \
   static void *initialize##passName##PassOnce(PassRegistry &Registry) {        \
     PassInfo *PI = new PassInfo(                                               \
@@ -59,8 +41,10 @@ class TargetMachine;
     Registry.registerPass(*PI, true);                                          \
     return PI;                                                                 \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
-    CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce)                   \
+    call_once(Initialize##passName##PassFlag, initialize##passName##PassOnce,  \
+              std::ref(Registry));                                             \
   }
 
 #define INITIALIZE_PASS_BEGIN(passName, arg, name, cfg, analysis)              \
@@ -77,8 +61,10 @@ class TargetMachine;
   Registry.registerPass(*PI, true);                                            \
   return PI;                                                                   \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
-    CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce)                   \
+    call_once(Initialize##passName##PassFlag, initialize##passName##PassOnce,  \
+              std::ref(Registry));                                             \
   }
 
 #define INITIALIZE_PASS_WITH_OPTIONS(PassName, Arg, Name, Cfg, Analysis)       \
@@ -166,8 +152,10 @@ struct RegisterAnalysisGroup : public Re
     Registry.registerAnalysisGroup(&agName::ID, 0, *AI, false, true);          \
     return AI;                                                                 \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##agName##AnalysisGroupFlag);                \
   void llvm::initialize##agName##AnalysisGroup(PassRegistry &Registry) {       \
-    CALL_ONCE_INITIALIZATION(initialize##agName##AnalysisGroupOnce)            \
+    call_once(Initialize##agName##AnalysisGroupFlag,                           \
+              initialize##agName##AnalysisGroupOnce, std::ref(Registry));      \
   }
 
 #define INITIALIZE_AG_PASS(passName, agName, arg, name, cfg, analysis, def)    \
@@ -184,8 +172,10 @@ struct RegisterAnalysisGroup : public Re
                                    true);                                      \
     return AI;                                                                 \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
-    CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce)                   \
+    call_once(Initialize##passName##PassFlag, initialize##passName##PassOnce,  \
+              std::ref(Registry));                                             \
   }
 
 #define INITIALIZE_AG_PASS_BEGIN(passName, agName, arg, n, cfg, analysis, def) \
@@ -203,8 +193,10 @@ struct RegisterAnalysisGroup : public Re
   Registry.registerAnalysisGroup(&agName::ID, &passName::ID, *AI, def, true);  \
   return AI;                                                                   \
   }                                                                            \
+  LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
-    CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce)                   \
+    call_once(Initialize##passName##PassFlag, initialize##passName##PassOnce,  \
+              std::ref(Registry));                                             \
   }
 
 //===---------------------------------------------------------------------------




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