[Mono-bugs] [Bug 58026][Wis] New - Add infrastructure for implementing icalls in IL

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Changed by vargaz@freemail.hu.

http://bugzilla.ximian.com/show_bug.cgi?id=58026

--- shadow/58026	2004-05-04 14:59:41.000000000 -0400
+++ shadow/58026.tmp.23262	2004-05-04 14:59:41.000000000 -0400
@@ -0,0 +1,50 @@
+Bug#: 58026
+Product: Mono: Runtime
+Version: unspecified
+OS: 
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Wishlist
+Component: misc
+AssignedTo: vargaz@freemail.hu                            
+ReportedBy: vargaz@freemail.hu               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: Add infrastructure for implementing icalls in IL
+
+Currently, all icalls are implemented in native C code. This means that
+calling them incures a performance penalty due to the managed->unmanaged
+transition. Also, they can't be inlined. For simple icalls, like 
+Array:Rank, the cost of the call and the transition is much greater than
+the cost of the operation itself. This is why under mono, 
+System.Buffer.BlockCopy is slower than System.Array.Copy (bug #53295).
+
+An alternative would be to implement some icalls in IL code like this:
+
+static guint8 array_rank_il [] = {
+    /* Load vtable ptr */
+    CEE_LDIND_I,
+    /* Load klass */
+    CEE_LDC_I4,
+    G_STRUCT_OFFSET (MonoVTable, klass),
+    CEE_ADD,
+    CEE_LDIND_I,
+    /* Load rank */
+    CEE_LDC_I4,
+    G_STRUCT_OFFSET (MonoClass, rank),
+    CEE_ADD,
+    CEE_LDIND_I
+    RET
+};
+
+Later:
+mono_register_il_icall (mono_defaults.array_class, "Rank", ....,
+array_rank_il);
+
+
+The JIT will need to be modified to handle these icalls and potentially
+inline them.