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| author | Georg-Johann Lay <avr@gjlay.de> | 2024-08-18 18:26:16 +0200 |
|---|---|---|
| committer | Georg-Johann Lay <avr@gjlay.de> | 2024-08-18 18:26:16 +0200 |
| commit | 1ed1dd521b8104dd76d010aaf78f130b1832864e (patch) | |
| tree | d019a28d934f431fb25bab986f8d05db27ecc482 /gcc/config | |
| parent | 22acd3c4d18dbd4d4d39d7770145fe3ec36073f6 (diff) | |
| download | gcc-1ed1dd521b8104dd76d010aaf78f130b1832864e.zip gcc-1ed1dd521b8104dd76d010aaf78f130b1832864e.tar.gz gcc-1ed1dd521b8104dd76d010aaf78f130b1832864e.tar.bz2 | |
AVR: Tweak 16-bit addition with const that didn't get a LD_REGS register.
The 16-bit additions like addhi3 have two forms: One with a scratch:QI
and one without, where the latter is required because reload cannot
deal with a scratch when spill code pops a 16-bit addition.
Passes like combine and fwprop1 may come up with the non-scratch version,
which is sub-optimal in the case when the addition is performed in a
NO_LD_REGS register because the operands will be spilled to LD_REGS.
Having a scratch:QI at disposal can lead to better code with less spills.
gcc/
* config/avr/avr.md (*add<mode>3_split) [!reload_completed]:
Add a scratch:QI to 16-bit additions with constant.
Diffstat (limited to 'gcc/config')
| -rw-r--r-- | gcc/config/avr/avr.md | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/gcc/config/avr/avr.md b/gcc/config/avr/avr.md index 57f4a08..c10709e 100644 --- a/gcc/config/avr/avr.md +++ b/gcc/config/avr/avr.md @@ -1724,12 +1724,28 @@ (match_operand:ALL2 2 "nonmemory_or_const_operand" "r,s,IJ YIJ,n Ynn")))] "" "#" - "&& reload_completed" + "&& 1" [(parallel [(set (match_dup 0) (plus:ALL2 (match_dup 1) (match_dup 2))) (clobber (reg:CC REG_CC))])] - "" + { + // Passes like combine and fwprop1 may remove the scratch from an + // addhi3 insn. Add the scratch again because having a QImode + // scratch reg available is better than spilling the operands in + // the case when we don't get a d-regs register. + if (! reload_completed + && const_operand (operands[2], <MODE>mode) + && ! stack_register_operand (operands[0], HImode) + && ! stack_register_operand (operands[1], HImode)) + { + emit (gen_add<mode>3_clobber (operands[0], operands[1], operands[2])); + DONE; + } + + if (! reload_completed) + FAIL; + } [(set_attr "isa" "*,*,adiw,*")]) ;; "*addhi3" |