Document that MCExpr::Mod is actually remainder.

Document that MCExpr::Div, Mod, and the comparison operators are all
signed operators.

Document that the comparison operators' results are target-dependent.

Document that the behavior of shr is target-dependent.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95619 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index afdaa00..e419043 100644
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -252,8 +252,8 @@
     }
 
     // FIXME: We need target hooks for the evaluation. It may be limited in
-    // width, and gas defines the result of comparisons differently from Apple
-    // as (the result is sign extended).
+    // width, and gas defines the result of comparisons and right shifts
+    // differently from Apple as.
     int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
     int64_t Result = 0;
     switch (ABE->getOpcode()) {