| Message ID | 1343602726.2304.16.camel@yam-132-YW-E178-FTW |
|---|---|
| State | New |
| Headers | show |
Oleg Endo <oleg.endo@t-online.de> wrote: > In cases where dynamic shifts are available, the ashlsi3_d pattern is > picked first and never converted back to a short sequence of constant > shifts. Preferring short constant shift sequences over dynamic shifts > can potentially reduce the need for an extra register to hold the shift > count. CSiBE shows some code size increases and decreases with this > patch. The increases seem to be due to some unlucky register > allocations. Overall there is a small decrease (-312 bytes on the whole > set for '-O2 -m4-single -ml -mpretend-cmove). > > Tested on rev 189916 with > make -k check RUNTESTFLAGS="--target_board=sh-sim > \{-m2/-ml,-m2/-mb,-m2a/-mb,-m2a-single/-mb,-m4/-ml,-m4/-mb, > -m4-single/-ml,-m4-single/-mb,-m4a-single/-ml,-m4a-single/-mb}" > > and no new failures. > > OK? OK. Regards, kaz
Index: gcc/config/sh/sh.md =================================================================== --- gcc/config/sh/sh.md (revision 189916) +++ gcc/config/sh/sh.md (working copy) @@ -3533,7 +3533,12 @@ } else if (!satisfies_constraint_P27 (operands[2])) { - emit_insn (gen_ashlsi3_n (operands[0], operands[1], operands[2])); + /* This must happen before reload, otherwise the constant will be moved + into a register due to the "r" constraint, after which this split + cannot be done anymore. + Unfortunately the move insn will not always be eliminated. */ + emit_move_insn (operands[0], operands[1]); + gen_shifty_op (ASHIFT, operands); DONE; }
Hello, In cases where dynamic shifts are available, the ashlsi3_d pattern is picked first and never converted back to a short sequence of constant shifts. Preferring short constant shift sequences over dynamic shifts can potentially reduce the need for an extra register to hold the shift count. CSiBE shows some code size increases and decreases with this patch. The increases seem to be due to some unlucky register allocations. Overall there is a small decrease (-312 bytes on the whole set for '-O2 -m4-single -ml -mpretend-cmove). Tested on rev 189916 with make -k check RUNTESTFLAGS="--target_board=sh-sim \{-m2/-ml,-m2/-mb,-m2a/-mb,-m2a-single/-mb,-m4/-ml,-m4/-mb, -m4-single/-ml,-m4-single/-mb,-m4a-single/-ml,-m4a-single/-mb}" and no new failures. OK? Cheers, Oleg ChangeLog: PR target/54089 * config/sh/sh.md (ashlsi3_d): Invoke gen_shifty_op directly instead of trying to emit ashlsi3_n.