[PATCH] D20973: [esan] Specify which tool via a global variable

[Derek Bruening via llvm-commits]

bruening created this revision.
bruening added a reviewer: aizatsky.
bruening added subscribers: llvm-commits, eugenis, kcc, zhaoqin, vitalybuka.

Adds a global variable to specify the tool, to support handling early
interceptors that invoke instrumented code and require shadow memory to be
initialized prior to __esan_init() being invoked.

http://reviews.llvm.org/D20973

Files:
  lib/Transforms/Instrumentation/EfficiencySanitizer.cpp

Index: lib/Transforms/Instrumentation/EfficiencySanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/EfficiencySanitizer.cpp
+++ lib/Transforms/Instrumentation/EfficiencySanitizer.cpp
@@ -72,6 +72,10 @@
 static const char *const EsanInitName = "__esan_init";
 static const char *const EsanExitName = "__esan_exit";
 
+// We need to specify the tool to the runtime earlier than
+// the ctor is called in some cases, so we set a global variable.
+static const char *const EsanWhichToolName = "__esan_which_tool";
+
 // We must keep these Shadow* constants consistent with the esan runtime.
 // FIXME: Try to place these shadow constants, the names of the __esan_*
 // interface functions, and the ToolType enum into a header shared between
@@ -430,14 +434,23 @@
   // Create the variable passed to EsanInit and EsanExit.
   Constant *ToolInfoArg = createEsanInitToolInfoArg(M);
   // Constructor
+  // We specify the tool type both in the EsanWhichToolName global
+  // and as an arg to the init routine as a sanity check.
   std::tie(EsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
       M, EsanModuleCtorName, EsanInitName, /*InitArgTypes=*/{OrdTy, Int8PtrTy},
       /*InitArgs=*/{
         ConstantInt::get(OrdTy, static_cast<int>(Options.ToolType)),
         ToolInfoArg});
   appendToGlobalCtors(M, EsanCtorFunction, EsanCtorAndDtorPriority);
 
   createDestructor(M, ToolInfoArg);
+
+  new GlobalVariable(M, OrdTy, true,
+                     GlobalValue::WeakAnyLinkage,
+                     ConstantInt::get(OrdTy,
+                                      static_cast<int>(Options.ToolType)),
+                     EsanWhichToolName);
+
   return true;
 }
 


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