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| author | Roger Sayle <roger@nextmovesoftware.com> | 2023-04-23 10:25:04 +0100 |
|---|---|---|
| committer | Roger Sayle <roger@nextmovesoftware.com> | 2023-04-23 10:25:04 +0100 |
| commit | 987caaae343ec8277391c875549859f8a288fd81 (patch) | |
| tree | a4530fccf777a79bb3725bf2acac988c6016c0b5 | |
| parent | 5830953a446959c5d8d9b569ffcd3e3bb16a06dc (diff) | |
| download | gcc-987caaae343ec8277391c875549859f8a288fd81.zip gcc-987caaae343ec8277391c875549859f8a288fd81.tar.gz gcc-987caaae343ec8277391c875549859f8a288fd81.tar.bz2 | |
[xstormy16] Improved SImode shifts by two bits.
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
2023-04-23 Roger Sayle <roger@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.
| -rw-r--r-- | gcc/config/stormy16/stormy16.cc | 23 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/xstormy16/shiftsi.c | 12 |
2 files changed, 35 insertions, 0 deletions
diff --git a/gcc/config/stormy16/stormy16.cc b/gcc/config/stormy16/stormy16.cc index 1ed619a..cf2f807 100644 --- a/gcc/config/stormy16/stormy16.cc +++ b/gcc/config/stormy16/stormy16.cc @@ -2105,6 +2105,29 @@ xstormy16_output_shift (machine_mode mode, enum rtx_code code, return r; } + /* For shifts of size 2, we can use two shifts of size 1. */ + if (size == 2) + { + switch (code) + { + case ASHIFT: + sprintf (r, "shl %s,#1 | rlc %s,#1 | shl %s,#1 | rlc %s,#1", + r0, r1, r0, r1); + break; + case ASHIFTRT: + sprintf (r, "asr %s,#1 | rrc %s,#1 | asr %s,#1 | rrc %s,#1", + r1, r0, r1, r0); + break; + case LSHIFTRT: + sprintf (r, "shr %s,#1 | rrc %s,#1 | shr %s,#1 | rrc %s,#1", + r1, r0, r1, r0); + break; + default: + gcc_unreachable (); + } + return r; + } + /* For large shifts, there are easy special cases. */ if (size == 16) { diff --git a/gcc/testsuite/gcc.target/xstormy16/shiftsi.c b/gcc/testsuite/gcc.target/xstormy16/shiftsi.c new file mode 100644 index 0000000..42bbca7 --- /dev/null +++ b/gcc/testsuite/gcc.target/xstormy16/shiftsi.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +unsigned long ashift_1(unsigned long x) { return x << 1; } +unsigned long ashift_2(unsigned long x) { return x << 2; } +unsigned long lshiftrt_1(unsigned long x) { return x >> 1; } +unsigned long lshiftrt_2(unsigned long x) { return x >> 2; } +long ashiftrt_1(long x) { return x >> 1; } +long ashiftrt_2(long x) { return x >> 2; } + +/* { dg-final { scan-assembler-not "mov " } } */ +/* { dg-final { scan-assembler-not "or " } } */ |