On 4/22/23 10:43, Roger Sayle wrote:
Currently on xstormy16 SImode shifts by a single bit require two
instructions, and shifts by other non-zero integer immediate constants
require five instructions. This patch implements the obvious optimization
that shifts by two bits can be done in four instructions, by using two
single-bit sequences.
Hence, ashift_2 was previously generated as:
mov r7,r2 | shl r2,#2 | shl r3,#2 | shr r7,#14 | or r3,r7
ret
and with this patch we now generate:
shl r2,#1 | rlc r3,#1 | shl r2,#1 | rlc r3,#1
ret
This patch has been tested by building a cross-compiler to xstormy16-elf
on x86_64-pc-linux-gnu, and confirming that the new test case passes with
"make -k check-gcc". Ok for mainline?
2023-04-22 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* config/stormy16/stormy16.cc (xstormy16_output_shift): Implement
SImode shifts by two by performing a single bit SImode shift twice.
gcc/testsuite/ChangeLog
* gcc.target/xstormy16/shiftsi.c: New test case.
OK.
jeff
