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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /gcc/config/sh/divcost-analysis
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+Analysis of cycle costs for SH4:
+
+-> udiv_le128: 5
+-> udiv_ge64k: 6
+-> udiv udiv_25: 10
+-> pos_divisor: 3
+-> pos_result linear: 5
+-> pos_result - -: 5
+-> div_le128: 7
+-> div_ge64k: 9
+sdivsi3 -> udiv_25 13
+udiv25 -> div_ge64k_end: 15
+div_ge64k_end -> rts: 13
+div_le128 -> div_le128_2: 2, r1 latency 3
+udiv_le128 -> div_le128_2: 2, r1 latency 3
+(u)div_le128 -> div_by_1: 9
+(u)div_le128 -> rts: 17
+div_by_1(_neg) -> rts: 4
+div_ge64k -> div_r8: 2
+div_ge64k -> div_ge64k_2: 3
+udiv_ge64k -> udiv_r8: 3
+udiv_ge64k -> div_ge64k_2: 3 + LS
+(u)div_ge64k -> div_ge64k_end: 13
+div_r8 -> div_r8_2: 2
+udiv_r8 -> div_r8_2: 2 + LS
+(u)div_r8 -> rts: 21
+
+-> - + neg_result: 5
+-> + - neg_result: 5
+-> div_le128_neg: 7
+-> div_ge64k_neg: 9
+-> div_r8_neg: 11
+-> <64k div_ge64k_neg_end: 28
+-> >=64k div_ge64k_neg_end: 22
+div_ge64k_neg_end ft -> rts: 14
+div_r8_neg_end -> rts: 4
+div_r8_neg -> div_r8_neg_end: 18
+div_le128_neg -> div_by_1_neg: 4
+div_le128_neg -> rts 18
+
+ sh4-200 absolute divisor range:
+ 1 [2..128] [129..64K) [64K..|dividend|/256] >=64K,>|dividend/256|
+udiv 18 22 38 32 30
+sdiv pos: 20 24 41 35 32
+sdiv neg: 15 25 42 36 33
+
+ sh4-300 absolute divisor range:
+ 8 bit 16 bit 24 bit > 24 bit
+udiv 15 35 28 25
+sdiv 14 36 34 31
+
+
+fp-based:
+
+unsigned: 42 + 3 + 3 (lingering ftrc latency + sts fpul,rx) at caller's site
+signed: 33 + 3 + 3 (lingering ftrc latency + sts fpul,rx) at caller's site
+
+call-div1: divisor range:
+ [1..64K) >= 64K
+unsigned: 63 58
+signed: 76 76
+
+SFUNC_STATIC call overhead:
+mov.l 0f,r1
+bsrf r1
+
+SFUNC_GOT call overhead - current:
+mov.l 0f,r1
+mova 0f,r0
+mov.l 1f,r2
+add r1,r0
+mov.l @(r0,r2),r0
+jmp @r0
+; 3 cycles worse than SFUNC_STATIC
+
+SFUNC_GOT call overhead - improved assembler:
+mov.l 0f,r1
+mova 0f,r0
+mov.l @(r0,r1),r0
+jmp @r0
+; 2 cycles worse than SFUNC_STATIC
+
+
+Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+
+Copying and distribution of this file, with or without modification,
+are permitted in any medium without royalty provided the copyright
+notice and this notice are preserved.