JIT: fix return type mismatch inlining block

If caller passes a directly substitutable expression whose
type is compatible with but not the same as the callee argument type,
and that argument is the callee's return value, the jit may
reject inlining the method because of a return type mismatch.

Fix is to retype the expressions we use in the callee's body
as the callee's type.

Closes dotnet/coreclr#11211.

Commit migrated from https://github.com/dotnet/coreclr/commit/7f8a620ea74dfb57e52320601addda68e2f53f53

diff --git a/src/coreclr/src/jit/importer.cpp b/src/coreclr/src/jit/importer.cpp
index 2e3ca81..c55aaf1 100644 (file)
--- a/src/coreclr/src/jit/importer.cpp
+++ b/src/coreclr/src/jit/importer.cpp
@@ -17947,8 +17947,12 @@ GenTreePtr Compiler::impInlineFetchArg(unsigned lclNum, InlArgInfo* inlArgInfo,
         op1               = argInfo.argNode;
         argInfo.argTmpNum = op1->gtLclVarCommon.gtLclNum;
 
-        // Use an equivalent copy if this is the second or subsequent use.
-        if (argInfo.argIsUsed)
+        // Use an equivalent copy if this is the second or subsequent
+        // use, or if we need to retype.
+        //
+        // Note argument type mismatches that prevent inlining should
+        // have been caught in impInlineInitVars.
+        if (argInfo.argIsUsed || (op1->TypeGet() != lclTyp))
         {
             assert(op1->gtOper == GT_LCL_VAR);
             assert(lclNum == op1->gtLclVar.gtLclILoffs);