WorkAround for #25050. (#25316)

* WorkAround for #25050.

A temporary workaround to push the milestone for this issue to 3.next.

* Response review.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/jit/emit.h b/src/jit/emit.h
index 595e2840b5..63d1c7c2bc 100644
--- a/src/jit/emit.h
+++ b/src/jit/emit.h
@@ -884,6 +884,16 @@ protected:
         }
         void idCodeSize(unsigned sz)
         {
+            if (sz > 15)
+            {
+                // This is a temporary workaround for non-precise instr size
+                // estimator on XARCH. It often overestimates sizes and can
+                // return value more than 15 that doesn't fit in 4 bits _idCodeSize.
+                // If somehow we generate instruction that needs more than 15 bytes we
+                // will fail on another assert in emit.cpp: noway_assert(id->idCodeSize() >= csz).
+                // Issue https://github.com/dotnet/coreclr/issues/25050.
+                sz = 15;
+            }
             assert(sz <= 15); // Intel decoder limit.
             _idCodeSize = sz;
             assert(sz == _idCodeSize);