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__FP_BASE__的說明 http://forum.andestech.com/viewtopic.php?f=16&t=579 |
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Author: | cindy [ Wed May 16, 2012 11:49 am ] |
Post subject: | __FP_BASE__的說明 |
主要是由 post-opt 加入的, linker則是負責填上值 __FP_BASE__是用來做 fp-as-gp optimization 例如 lwi.gp $r0, [+0] lwi.gp $r1, [+4] lwi.gp $r2, [+8] lwi.gp $r3, [+12] 這樣需要 4*4 = 16 bytes 但改成 addi.gp $fp, __FP_BASE__ ; la $fp, __FP_BASE__ lwi37.fp $r0, [+0] lwi37.fp $r1, [+4] lwi37.fp $r2, [+8] lwi37.fp $r3, [+12] 則只要 4 + 2*4 = 12 bytes 一般來說, la $fp, __FP_BASE__這道會在要做這個 optimization的function prologue |
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