[MSP430][Clang] Remove support for -mmcu=msp430

[jozefl]

Summary

The -mmcu= option accepts a generic MCU named "msp430", which sets the
CPU to msp430 and disables hardware multiply support.

The current purpose of accepting this value is to allow -mmcu= to be
used as an alias for -mcpu=, however there are some downsides to doing
this. -mmcu= provides additional features that will interfere
with the expected behavior if the user tries to to use it as an alias
for -mcpu=.

-mmcu=msp430 will conflict with -mhwmult=, since the "msp430" MCU is
defined to have no hardware multiply support, so the user will not be
able to set an explicit hardware multiply version.

-mmcu=msp430 will put "-Tmsp430.ld" on the linker command line, however
TI's support files do not provide a linker script with this name and so
the user would have to explicitly create it.

If the patch is acceptable, I would appreciate it if someone would apply
it for me, as I do not have commit access.

Thanks,
Jozef

[jozefl]

Pinging for review.

Thanks,
Jozef

[jozefl]

Pinging for review.

Thanks,
Jozef

[asl]

LGTM, thanks!

clang/include/clang/Basic/MSP430Target.def

 MSP430_MCU_FEAT("msp430afe253", "16bit")
 
 // With 32 Bit Hardware Multiplier
 MSP430_MCU_FEAT("msp430f4783", "32bit")
 MSP430_MCU_FEAT("msp430f4793", "32bit")
 MSP430_MCU_FEAT("msp430f4784", "32bit")
 MSP430_MCU_FEAT("msp430f4794", "32bit")
 
-// Generic MSUs
-MSP430_MCU("msp430")
+// Generic MCUs
 MSP430_MCU("msp430i2xxgeneric")
 
 #undef MSP430_MCU
 #undef MSP430_MCU_FEAT

clang/test/Driver/msp430-mmcu.c

 // RUN: %clang %s -### -no-canonical-prefixes -target msp430 -mmcu=msp430c111 2>&1 \
 // RUN:   | FileCheck -check-prefix=MSP430-C111 %s
 
 // MSP430-C111: clang{{.*}} "-cc1" {{.*}} "-D__MSP430C111__"
 // MSP430-C111: msp430-elf-ld{{.*}} "-Tmsp430c111.ld"
 
 // RUN: %clang %s -### -no-canonical-prefixes -target msp430 -mmcu=msp430i2020 2>&1 \
 // RUN:   | FileCheck -check-prefix=MSP430-I2020 %s
 
 // MSP430-I2020: clang{{.*}} "-cc1" {{.*}} "-D__MSP430i2020__"
 // MSP430-I2020: msp430-elf-ld{{.*}} "-Tmsp430i2020.ld"
 
 // RUN: %clang %s -### -no-canonical-prefixes -target msp430 -mmcu=not-a-mcu 2>&1 \
 // RUN:   | FileCheck -check-prefix=MSP430-UNSUP %s
 
 // MSP430-UNSUP: error: the clang compiler does not support 'not-a-mcu'
+
+// The generic MCU name "msp430" is not supported.
+// RUN: %clang %s -### -no-canonical-prefixes -target msp430 -mmcu=msp430 2>&1 \
+// RUN:   | FileCheck -check-prefix=MSP430 %s
+
+// MSP430: error: the clang compiler does not support 'msp430'