[PATCH] DataFlowSanitizer: Replace non-instrumented aliases of instrumented functions, and vice versa, with wrappers.

[Peter Collingbourne]

Hi eugenis,

http://llvm-reviews.chandlerc.com/D1442

Files:
  lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
  test/Instrumentation/DataFlowSanitizer/Inputs/abilist.txt
  test/Instrumentation/DataFlowSanitizer/abilist.ll

Index: lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -470,7 +470,8 @@
       FnsToInstrument.push_back(&*i);
   }
 
-  // Give function aliases prefixes when necessary.
+  // Give function aliases prefixes when necessary, and build wrappers where the
+  // instrumentedness is inconsistent.
   for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) {
     GlobalAlias *GA = &*i;
     ++i;
@@ -481,6 +482,16 @@
       bool GAInst = isInstrumented(GA), FInst = isInstrumented(F);
       if (GAInst && FInst) {
         addGlobalNamePrefix(GA);
+      } else if (GAInst != FInst) {
+        // Non-instrumented alias of an instrumented function, or vice versa.
+        // Replace the alias with a native-ABI wrapper of the aliasee.  The pass
+        // below will take care of instrumenting it.
+        Function *NewF =
+            buildWrapperFunction(F, "", GA->getLinkage(), F->getFunctionType());
+        GA->replaceAllUsesWith(NewF);
+        NewF->takeName(GA);
+        GA->eraseFromParent();
+        FnsToInstrument.push_back(NewF);
       }
     }
   }
Index: test/Instrumentation/DataFlowSanitizer/Inputs/abilist.txt
===================================================================
--- test/Instrumentation/DataFlowSanitizer/Inputs/abilist.txt
+++ test/Instrumentation/DataFlowSanitizer/Inputs/abilist.txt
@@ -1,5 +1,5 @@
-fun:discard=uninstrumented
-fun:discard=discard
+fun:discard*=uninstrumented
+fun:discard*=discard
 
 fun:functional=uninstrumented
 fun:functional=functional
Index: test/Instrumentation/DataFlowSanitizer/abilist.ll
===================================================================
--- test/Instrumentation/DataFlowSanitizer/abilist.ll
+++ test/Instrumentation/DataFlowSanitizer/abilist.ll
@@ -29,6 +29,12 @@
   ret void
 }
 
+; CHECK: define i32 (i32, i32)* @discardg(i32)
+; CHECK: %[[CALL:.*]] = call { i32 (i32, i32)*, i16 } @"dfs$g"(i32 %0, i16 0)
+; CHECK: %[[XVAL:.*]] = extractvalue { i32 (i32, i32)*, i16 } %[[CALL]], 0
+; CHECK: ret {{.*}} %[[XVAL]]
+ at discardg = alias i32 (i32, i32)* (i32)* @g
+
 ; CHECK: define linkonce_odr { i32, i16 } @"dfsw$custom2"(i32, i32, i16, i16)
 ; CHECK: %[[LABELRETURN2:.*]] = alloca i16
 ; CHECK: %[[RV:.*]] = call i32 @__dfsw_custom2
@@ -38,10 +44,17 @@
 ; CHECK: ret { i32, i16 }
 
 ; CHECK: @"dfs$g"
-define i32 (i32, i32)* @g() {
+define i32 (i32, i32)* @g(i32) {
   ; CHECK: ret {{.*}} @"dfsw$custom2"
   ret i32 (i32, i32)* @custom2
 }
 
+; CHECK: define { i32, i16 } @"dfs$adiscard"(i32, i32, i16, i16)
+; CHECK: %[[CALL:.*]] = call i32 @discard(i32 %0, i32 %1)
+; CHECK: %[[IVAL0:.*]] = insertvalue { i32, i16 } undef, i32 %[[CALL]], 0
+; CHECK: %[[IVAL1:.*]] = insertvalue { i32, i16 } %[[IVAL0]], i16 0, 1
+; CHECK: ret { i32, i16 } %[[IVAL1]]
+ at adiscard = alias i32 (i32, i32)* @discard
+
 ; CHECK: declare void @__dfsw_custom1(i32, i32, i16, i16)
 ; CHECK: declare i32 @__dfsw_custom2(i32, i32, i16, i16, i16*)
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