Jitstress fixes for tailcall tests

src/coreclr/src/jit/compiler.h

@@ -4021,7 +4021,7 @@ class Compiler
     }
     void impLoadArg(unsigned ilArgNum, IL_OFFSET offset);
     void impLoadLoc(unsigned ilLclNum, IL_OFFSET offset);
-    bool impReturnInstruction(BasicBlock* block, int prefixFlags, OPCODE& opcode);
+    bool impReturnInstruction(int prefixFlags, OPCODE& opcode);
 
 #ifdef _TARGET_ARM_
     void impMarkLclDstNotPromotable(unsigned tmpNum, GenTree* op, CORINFO_CLASS_HANDLE hClass);

src/coreclr/src/jit/importer.cpp

@@ -11476,7 +11476,7 @@ void Compiler::impImportBlockCode(BasicBlock* block)
             case CEE_RET:
                 prefixFlags &= ~PREFIX_TAILCALL; // ret without call before it
             RET:
-                if (!impReturnInstruction(block, prefixFlags, opcode))
+                if (!impReturnInstruction(prefixFlags, opcode))
                 {
                     return; // abort
                 }
@@ -16222,7 +16222,7 @@ GenTree* Compiler::impAssignSmallStructTypeToVar(GenTree* op, CORINFO_CLASS_HAND
 //    registers return values to suitable temps.
 //
 // Arguments:
-//     op -- call returning a struct in a registers
+//     op -- call returning a struct in registers
 //     hClass -- class handle for struct
 //
 // Returns:
@@ -16246,11 +16246,20 @@ GenTree* Compiler::impAssignMultiRegTypeToVar(GenTree* op, CORINFO_CLASS_HANDLE
 }
 #endif // FEATURE_MULTIREG_RET
 
-// do import for a return
-// returns false if inlining was aborted
-// opcode can be ret or call in the case of a tail.call
-bool Compiler::impReturnInstruction(BasicBlock* block, int prefixFlags, OPCODE& opcode)
+//------------------------------------------------------------------------
+// impReturnInstruction: import a return or an explicit tail call
+//
+// Arguments:
+//     prefixFlags -- active IL prefixes
+//     opcode -- [in, out] IL opcode
+//
+// Returns:
+//     True if import was successful (may fail for some inlinees)
+//
+bool Compiler::impReturnInstruction(int prefixFlags, OPCODE& opcode)
 {
+    const bool isTailCall = (prefixFlags & PREFIX_TAILCALL) != 0;
+
     if (tiVerificationNeeded)
     {
         verVerifyThisPtrInitialised();
@@ -16302,7 +16311,7 @@ bool Compiler::impReturnInstruction(BasicBlock* block, int prefixFlags, OPCODE&
                       (varTypeIsStruct(op2) && varTypeIsStruct(info.compRetType)));
 
 #ifdef DEBUG
-            if (opts.compGcChecks && info.compRetType == TYP_REF)
+            if (!isTailCall && opts.compGcChecks && (info.compRetType == TYP_REF))
             {
                 // DDB 3483  : JIT Stress: early termination of GC ref's life time in exception code path
                 // VSW 440513: Incorrect gcinfo on the return value under COMPlus_JitGCChecks=1 for methods with
@@ -16709,7 +16718,7 @@ bool Compiler::impReturnInstruction(BasicBlock* block, int prefixFlags, OPCODE&
     }
 
     // We must have imported a tailcall and jumped to RET
-    if (prefixFlags & PREFIX_TAILCALL)
+    if (isTailCall)
     {
 #if defined(FEATURE_CORECLR) || !defined(_TARGET_AMD64_)
         // Jit64 compat:

src/coreclr/src/jit/morph.cpp

@@ -6975,15 +6975,6 @@ GenTree* Compiler::fgMorphPotentialTailCall(GenTreeCall* call)
     }
 #endif
 
-#ifdef DEBUG
-    // DDB 99324: Just disable tailcall under compGcChecks stress mode.
-    if (opts.compGcChecks)
-    {
-        failTailCall("GcChecks");
-        return nullptr;
-    }
-#endif
-
     // We have to ensure to pass the incoming retValBuf as the
     // outgoing one. Using a temp will not do as this function will
     // not regain control to do the copy. This can happen when inlining

src/coreclr/tests/src/JIT/Directed/tailcall/tailcall.ilproj

@@ -9,4 +9,14 @@
   <ItemGroup>
     <Compile Include="$(MSBuildProjectName).il" />
   </ItemGroup>
+  <PropertyGroup>
+    <CLRTestBatchPreCommands><![CDATA[
+$(CLRTestBatchPreCommands)
+set COMPlus_JitStressModeNamesNot=STRESS_UNSAFE_BUFFER_CHECKS
+]]></CLRTestBatchPreCommands>
+    <BashCLRTestPreCommands><![CDATA[
+$(BashCLRTestPreCommands)
+export COMPlus_JitStressModeNamesNot=STRESS_UNSAFE_BUFFER_CHECKS
+]]></BashCLRTestPreCommands>
+  </PropertyGroup>
 </Project>