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| author | Roger Sayle <roger@eyesopen.com> | 2004-06-29 17:13:08 +0000 |
|---|---|---|
| committer | Roger Sayle <sayle@gcc.gnu.org> | 2004-06-29 17:13:08 +0000 |
| commit | 1c234fcb7273f09aa3cb32274c58e7c2ed0abcb3 (patch) | |
| tree | 3526890960c85ad4ae1680858ad18c224437b6fc /gcc | |
| parent | e1514303f2550329accaf2fe3b7eec9ca54f9724 (diff) | |
| download | gcc-1c234fcb7273f09aa3cb32274c58e7c2ed0abcb3.zip gcc-1c234fcb7273f09aa3cb32274c58e7c2ed0abcb3.tar.gz gcc-1c234fcb7273f09aa3cb32274c58e7c2ed0abcb3.tar.bz2 | |
expmed.c (expand_smod_pow2): Provide alternate implementations that avoid conditional jumps...
* expmed.c (expand_smod_pow2): Provide alternate implementations
that avoid conditional jumps, and choose between them based upon
the target's rtx_costs.
From-SVN: r83861
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/expmed.c | 47 |
2 files changed, 42 insertions, 11 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 59f35c1..36fedf6 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2004-06-29 Roger Sayle <roger@eyesopen.com> + + * expmed.c (expand_smod_pow2): Provide alternate implementations + that avoid conditional jumps, and choose between them based upon + the target's rtx_costs. + 2004-06-29 Andrew Pinski <apinski@apple.com> * tree-sra.c: Include expr.h for definition of MOVE_RATIO. diff --git a/gcc/expmed.c b/gcc/expmed.c index 6316f99..bb60ba1 100644 --- a/gcc/expmed.c +++ b/gcc/expmed.c @@ -3064,7 +3064,7 @@ static rtx expand_smod_pow2 (enum machine_mode mode, rtx op0, HOST_WIDE_INT d) { unsigned HOST_WIDE_INT mask; - rtx result, temp, label; + rtx result, temp, shift, label; int logd; logd = floor_log2 (d); @@ -3079,17 +3079,42 @@ expand_smod_pow2 (enum machine_mode mode, rtx op0, HOST_WIDE_INT d) if (signmask) { signmask = force_reg (mode, signmask); - temp = expand_binop (mode, xor_optab, op0, signmask, - NULL_RTX, 1, OPTAB_LIB_WIDEN); - temp = expand_binop (mode, sub_optab, temp, signmask, - NULL_RTX, 0, OPTAB_LIB_WIDEN); mask = ((HOST_WIDE_INT) 1 << logd) - 1; - temp = expand_binop (mode, and_optab, temp, GEN_INT (mask), - NULL_RTX, 1, OPTAB_LIB_WIDEN); - temp = expand_binop (mode, xor_optab, temp, signmask, - NULL_RTX, 1, OPTAB_LIB_WIDEN); - temp = expand_binop (mode, sub_optab, temp, signmask, - NULL_RTX, 1, OPTAB_LIB_WIDEN); + shift = GEN_INT (GET_MODE_BITSIZE (mode) - logd); + + /* Use the rtx_cost of a LSHIFTRT instruction to determine + which instruction sequence to use. If logical right shifts + are expensive the use 2 XORs, 2 SUBs and an AND, otherwise + use a LSHIFTRT, 1 ADD, 1 SUB and an AND. */ + + temp = gen_rtx_LSHIFTRT (mode, result, shift); + if (lshr_optab->handlers[mode].insn_code == CODE_FOR_nothing + || rtx_cost (temp, SET) > COSTS_N_INSNS (2)) + { + temp = expand_binop (mode, xor_optab, op0, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, sub_optab, temp, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, and_optab, temp, GEN_INT (mask), + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, xor_optab, temp, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, sub_optab, temp, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + } + else + { + signmask = expand_binop (mode, lshr_optab, signmask, shift, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + signmask = force_reg (mode, signmask); + + temp = expand_binop (mode, add_optab, op0, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, and_optab, temp, GEN_INT (mask), + NULL_RTX, 1, OPTAB_LIB_WIDEN); + temp = expand_binop (mode, sub_optab, temp, signmask, + NULL_RTX, 1, OPTAB_LIB_WIDEN); + } return temp; } } |