Merge pull request #2648 from sivarv/founddiff2

Fix to issue #2349 - Assertion failed '!foundDiff' in 'Node[__Canon][System.__Canon]:Search(ref,ref):ref:this' in lsra.cpp

1 files changed, 9 insertions, 0 deletions

diff --git a/src/jit/morph.cpp b/src/jit/morph.cpp
index 4d3b086339..35d8b1bd2b 100644
--- a/src/jit/morph.cpp
+++ b/src/jit/morph.cpp
@@ -6602,9 +6602,18 @@ GenTreePtr          Compiler::fgMorphCall(GenTreeCall* call)
 #if FEATURE_TAILCALL_OPT
         // TODO-CQ: enable the transformation when the method has a struct parameter that can be passed in a register
         // or return type is a struct that can be passed in a register.
+        //
+        // TODO-CQ: if the method being compiled requires generic context reported in gc-info (either through
+        // hidden generic context param or through keep alive thisptr), then while transforming a recursive
+        // call to such a method requires that the generic context stored on stack slot be updated.  Right now,
+        // fgMorphRecursiveFastTailCallIntoLoop() is not handling update of generic context while transforming
+        // a recursive call into a loop.  Another option is to modify gtIsRecursiveCall() to check that the
+        // generic type parameters of both caller and callee generic method are the same.
         if (opts.compTailCallLoopOpt &&
             canFastTailCall &&
             gtIsRecursiveCall(call) &&
+            !lvaReportParamTypeArg() &&
+            !lvaKeepAliveAndReportThis() &&
             !call->IsVirtual() &&
             !hasStructParam &&
             !varTypeIsStruct(call->TypeGet()))