remove dead code elimination option (#7669)

doc/basicopt.txt

@@ -29,7 +29,6 @@ Options:
   --nanChecks:on|off        turn NaN checks on|off
   --infChecks:on|off        turn Inf checks on|off
   --nilChecks:on|off        turn nil checks on|off
-  --deadCodeElim:on|off     whole program dead code elimination on|off
   --opt:none|speed|size     optimize not at all or for speed|size
                             Note: use -d:release for a release build!
   --debugger:native|endb    use native debugger (gdb) | ENDB (experimental)

doc/manual.rst

@@ -6768,22 +6768,6 @@ the created global variables within a module is not defined, but all of them
 will be initialized after any top-level variables in their originating module
 and before any variable in a module that imports it.
 
-deadCodeElim pragma
--------------------
-The ``deadCodeElim`` pragma only applies to whole modules: It tells the
-compiler to activate (or deactivate) dead code elimination for the module the
-pragma appears in.
-
-The ``--deadCodeElim:on`` command line switch has the same effect as marking
-every module with ``{.deadCodeElim:on}``. However, for some modules such as
-the GTK wrapper it makes sense to *always* turn on dead code elimination -
-no matter if it is globally active or not.
-
-Example:
-
-.. code-block:: nim
-  {.deadCodeElim: on.}
-
 
 ..
   NoForward pragma

doc/nimc.rst

@@ -181,7 +181,7 @@ generated; use the ``--symbolFiles:on`` command line switch to activate them.
 
 Unfortunately due to technical reasons the ``--symbolFiles:on`` needs
 to *aggregate* some generated C code. This means that the resulting executable
-might contain some cruft even when dead code elimination is turned on. So
+might contain some cruft even with dead code elimination. So
 the final release build should be done with ``--symbolFiles:off``.
 
 Due to the aggregation of C code it is also recommended that each project
@@ -439,7 +439,7 @@ target.
 
 For example, to generate code for an `AVR`:idx: processor use this command::
 
-  nim c --cpu:avr --os:standalone --deadCodeElim:on --genScript x.nim
+  nim c --cpu:avr --os:standalone --genScript x.nim
 
 For the ``standalone`` target one needs to provide
 a file ``panicoverride.nim``.