X-Git-Url: https://oss.titaniummirror.com/gitweb?a=blobdiff_plain;f=gcc%2Fconfig%2Fsh%2Fdivcost-analysis;fp=gcc%2Fconfig%2Fsh%2Fdivcost-analysis;h=d93f04355f46ed873990f8c7c57c56d21d1c97c2;hb=6fed43773c9b0ce596dca5686f37ac3fc0fa11c0;hp=0000000000000000000000000000000000000000;hpb=27b11d56b743098deb193d510b337ba22dc52e5c;p=msp430-gcc.git diff --git a/gcc/config/sh/divcost-analysis b/gcc/config/sh/divcost-analysis new file mode 100644 index 00000000..d93f0435 --- /dev/null +++ b/gcc/config/sh/divcost-analysis @@ -0,0 +1,81 @@ +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