Support modulo operator #27
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jserv
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Nov 5, 2020
jserv
reviewed
Nov 5, 2020
| @@ -367,6 +368,14 @@ void code_generate() | |||
| if (dump_ir == 1) | |||
| printf(" x%d /= x%d", dest_reg, OP_reg); | |||
| break; | |||
| case OP_mod: | |||
| emit(__div(__AL, OP_reg + 1, OP_reg, dest_reg)); | |||
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Both div and mul instruction are heavier. Instead, you can add shortcut for power-of-2. That is, convert the original modulo operation into n & (d - 1) if d is power-of-2. You should implement the shortcut in src/cfront.c.
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I think only global expression can do this shortcut because shecc can't determine the value of operand in local expression before execution time. Can we ignore optimization for local expression in this patch?
BTW, relative issue#28 and detailed information was sent.
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Sure, let's merge this change first. Do append the comments with TODO: optimize ...
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