Register preservation rules
---------------------------
-Register preservation rules match the ELF ABI calling sequence with the
-following differences:
-
-+------------------------------------------------------------------------+
-| For the sc instruction, differences with the ELF ABI |
-+--------------+--------------+------------------------------------------+
-| r0 | Volatile | (System call number.) |
-| rr3 | Volatile | (Parameter 1, and return value.) |
-| rr4-r8 | Volatile | (Parameters 2-6.) |
-| rcr0 | Volatile | (cr0.SO is the return error condition.) |
-| rcr1, cr5-7 | Nonvolatile | |
-| rlr | Nonvolatile | |
-+--------------+--------------+------------------------------------------+
-| For the scv 0 instruction, differences with the ELF ABI |
-+--------------+--------------+------------------------------------------+
-| r0 | Volatile | (System call number.) |
-| r3 | Volatile | (Parameter 1, and return value.) |
-| r4-r8 | Volatile | (Parameters 2-6.) |
-+--------------+--------------+------------------------------------------+
+Register preservation rules match the ELF ABI calling sequence with some
+differences.
+
+For the sc instruction, the differences from the ELF ABI are as follows:
+
++--------------+--------------------+-----------------------------------------+
+| Register | Preservation Rules | Purpose |
++==============+====================+=========================================+
+| r0 | Volatile | (System call number.) |
++--------------+--------------------+-----------------------------------------+
+| r3 | Volatile | (Parameter 1, and return value.) |
++--------------+--------------------+-----------------------------------------+
+| r4-r8 | Volatile | (Parameters 2-6.) |
++--------------+--------------------+-----------------------------------------+
+| cr0 | Volatile | (cr0.SO is the return error condition.) |
++--------------+--------------------+-----------------------------------------+
+| cr1, cr5-7 | Nonvolatile | |
++--------------+--------------------+-----------------------------------------+
+| lr | Nonvolatile | |
++--------------+--------------------+-----------------------------------------+
+
+For the scv 0 instruction, the differences from the ELF ABI are as follows:
+
++--------------+--------------------+-----------------------------------------+
+| Register | Preservation Rules | Purpose |
++==============+====================+=========================================+
+| r0 | Volatile | (System call number.) |
++--------------+--------------------+-----------------------------------------+
+| r3 | Volatile | (Parameter 1, and return value.) |
++--------------+--------------------+-----------------------------------------+
+| r4-r8 | Volatile | (Parameters 2-6.) |
++--------------+--------------------+-----------------------------------------+
All floating point and vector data registers as well as control and status
registers are nonvolatile.