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| author | Jim Wilson <wilson@gcc.gnu.org> | 1992-12-31 12:55:33 -0800 |
|---|---|---|
| committer | Jim Wilson <wilson@gcc.gnu.org> | 1992-12-31 12:55:33 -0800 |
| commit | ed359ebc317acbf7e2d948232f11e98a701277d0 (patch) | |
| tree | 71421c82d0fcd1dd514dc6ce697dc377073d8c93 /gcc | |
| parent | 483404b6dc558ee5c38657e06c66ba059d7b25aa (diff) | |
| download | gcc-ed359ebc317acbf7e2d948232f11e98a701277d0.zip gcc-ed359ebc317acbf7e2d948232f11e98a701277d0.tar.gz gcc-ed359ebc317acbf7e2d948232f11e98a701277d0.tar.bz2 | |
Add peephole to eliminate unecessary clear instructions
in strict_low_part insn sequences.
From-SVN: r3015
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/config/m68k/m68k.md | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/gcc/config/m68k/m68k.md b/gcc/config/m68k/m68k.md index 4713213..09fb81b 100644 --- a/gcc/config/m68k/m68k.md +++ b/gcc/config/m68k/m68k.md @@ -4884,6 +4884,29 @@ return \"\"; }") +(define_peephole + [(set (match_operand:SI 0 "register_operand" "=d") + (const_int 0)) + (set (strict_low_part (subreg:HI (match_dup 0) 0)) + (match_operand:HI 1 "general_operand" "rmn"))] + "strict_low_part_peephole_ok (HImode, prev_nonnote_insn (insn), operands[0])" + "* +{ + if (GET_CODE (operands[1]) == CONST_INT) + { + if (operands[1] == const0_rtx + && (DATA_REG_P (operands[0]) + || GET_CODE (operands[0]) == MEM) + /* clr insns on 68000 read before writing. + This isn't so on the 68010, but we have no alternative for it. */ + && (TARGET_68020 + || !(GET_CODE (operands[0]) == MEM + && MEM_VOLATILE_P (operands[0])))) + return \"clr%.w %0\"; + } + return \"move%.w %1,%0\"; +}") + ;; dbCC peepholes ;; ;; Turns |