[llvm] r346256 - [CodeExtractor] Do not extract calls to eh_typeid_for (PR39545)

[Vedant Kumar via llvm-commits]

Author: vedantk
Date: Tue Nov  6 11:06:08 2018
New Revision: 346256

URL: http://llvm.org/viewvc/llvm-project?rev=346256&view=rev
Log:
[CodeExtractor] Do not extract calls to eh_typeid_for (PR39545)

The lowering for a call to eh_typeid_for changes when it's moved from
one function to another.

There are several proposals for fixing this issue in llvm.org/PR39545.
Until some solution is in place, do not allow CodeExtractor to extract
calls to eh_typeid_for, as that results in serious miscompilations.

Added:
    llvm/trunk/test/Transforms/HotColdSplit/eh-typeid-for.ll
Modified:
    llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp

Modified: llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp?rev=346256&r1=346255&r2=346256&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/CodeExtractor.cpp Tue Nov  6 11:06:08 2018
@@ -168,14 +168,22 @@ static bool isBlockValidForExtraction(co
       continue;
     }
 
-    if (const CallInst *CI = dyn_cast<CallInst>(I))
-      if (const Function *F = CI->getCalledFunction())
-        if (F->getIntrinsicID() == Intrinsic::vastart) {
+    if (const CallInst *CI = dyn_cast<CallInst>(I)) {
+      if (const Function *F = CI->getCalledFunction()) {
+        auto IID = F->getIntrinsicID();
+        if (IID == Intrinsic::vastart) {
           if (AllowVarArgs)
             continue;
           else
             return false;
         }
+
+        // Currently, we miscompile outlined copies of eh_typid_for. There are
+        // proposals for fixing this in llvm.org/PR39545.
+        if (IID == Intrinsic::eh_typeid_for)
+          return false;
+      }
+    }
   }
 
   return true;

Added: llvm/trunk/test/Transforms/HotColdSplit/eh-typeid-for.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/HotColdSplit/eh-typeid-for.ll?rev=346256&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/HotColdSplit/eh-typeid-for.ll (added)
+++ llvm/trunk/test/Transforms/HotColdSplit/eh-typeid-for.ll Tue Nov  6 11:06:08 2018
@@ -0,0 +1,26 @@
+; RUN: opt -hotcoldsplit -S < %s | FileCheck %s
+
+; Do not outline calls to @llvm.eh.typeid.for. See llvm.org/PR39545.
+
+ at _ZTIi = external constant i8*
+
+; CHECK-LABEL: @fun
+; CHECK-NOT: call {{.*}}@fun.cold.1
+define void @fun() {
+entry:
+  br i1 undef, label %if.then, label %if.else
+
+if.then:
+  ret void
+
+if.else:
+  %t = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+  call void @sink()
+  call void @sink()
+  call void @sink()
+  ret void
+}
+
+declare void @sink() cold
+
+declare i32 @llvm.eh.typeid.for(i8*)