RISC-V: Add RV32E multilibs

This commit adds a minimum set of multilibs required to build the RV32E
(embedded) targets:

* rv32em, ilp32e
* rv32emc, ilp32e

Note that we build a separate multilib variant for the C (compressed)
extension instead of mapping to the uncompressed variant because the
RV32E instruction set is intended to be used in highly resource-
constrained devices such as microcontrollers.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

gcc/config/riscv/t-zephyr

@@ -1,6 +1,6 @@
 # This file was generated by multilib-generator with the command:
-#  ./multilib-generator rv32im-ilp32--c rv32imac-ilp32-- rv32imafc-ilp32f-- rv32imafd-ilp32d--c rv64imac-lp64-- rv64imafdc-lp64d-- rv64imafd-lp64d--
-MULTILIB_OPTIONS = march=rv32im/march=rv32imc/march=rv32imac/march=rv32imafc/march=rv32imafd/march=rv32imafdc/march=rv32g/march=rv32gc/march=rv64imac/march=rv64imafdc/march=rv64gc/march=rv64imafd/march=rv64g mabi=ilp32/mabi=ilp32f/mabi=ilp32d/mabi=lp64/mabi=lp64d
+#  ./multilib-generator rv32im-ilp32--c rv32imac-ilp32-- rv32imafc-ilp32f-- rv32imafd-ilp32d--c rv32em-ilp32e-rv32ema- rv32emc-ilp32e-rv32emac- rv64imac-lp64-- rv64imafdc-lp64d-- rv64imafd-lp64d--
+MULTILIB_OPTIONS = march=rv32im/march=rv32imc/march=rv32imac/march=rv32imafc/march=rv32imafd/march=rv32imafdc/march=rv32g/march=rv32gc/march=rv32em/march=rv32ema/march=rv32emc/march=rv32emac/march=rv64imac/march=rv64imafdc/march=rv64gc/march=rv64imafd/march=rv64g mabi=ilp32/mabi=ilp32f/mabi=ilp32d/mabi=ilp32e/mabi=lp64/mabi=lp64d
 MULTILIB_DIRNAMES = rv32im \
 rv32imc \
 rv32imac \
@@ -9,13 +9,18 @@ rv32imafd \
 rv32imafdc \
 rv32g \
 rv32gc \
+rv32em \
+rv32ema \
+rv32emc \
+rv32emac \
 rv64imac \
 rv64imafdc \
 rv64gc \
 rv64imafd \
 rv64g ilp32 \
 ilp32f \
 ilp32d \
+ilp32e \
 lp64 \
 lp64d
 MULTILIB_OPTIONS += mcmodel=medany
@@ -24,6 +29,8 @@ MULTILIB_REQUIRED = march=rv32im/mabi=ilp32 \
 march=rv32imac/mabi=ilp32 \
 march=rv32imafc/mabi=ilp32f \
 march=rv32imafd/mabi=ilp32d \
+march=rv32em/mabi=ilp32e \
+march=rv32emc/mabi=ilp32e \
 march=rv64imac/mabi=lp64 \
 march=rv64imafdc/mabi=lp64d \
 march=rv64imafd/mabi=lp64d \
@@ -34,5 +41,7 @@ MULTILIB_REUSE = march.rv32im/mabi.ilp32=march.rv32imc/mabi.ilp32 \
 march.rv32imafd/mabi.ilp32d=march.rv32imafdc/mabi.ilp32d \
 march.rv32imafd/mabi.ilp32d=march.rv32g/mabi.ilp32d \
 march.rv32imafd/mabi.ilp32d=march.rv32gc/mabi.ilp32d \
+march.rv32em/mabi.ilp32e=march.rv32ema/mabi.ilp32e \
+march.rv32emc/mabi.ilp32e=march.rv32emac/mabi.ilp32e \
 march.rv64imafdc/mabi.lp64d=march.rv64gc/mabi.lp64d \
 march.rv64imafd/mabi.lp64d=march.rv64g/mabi.lp64d