3 Commits

Author	SHA1	Message	Date
svenpanne@chromium.org	dbce27047e	Fixed and improved code for integral division. Fixed and extended tests. ... Arithmetic right shifting is *not* division in two's complement representation, only in one's complement. So we convert to one's complement, shift, and go back to two's complement. By permutating the last steps, one can get efficient branch-free code. This insight comes from the paleozoic era of computer science, see the paper from 1976: Guy Lewis Steele Jr.: "Arithmetic Shifting Considered Harmful" ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-378.pdf This results in better and more correct code than our previous "neg/shift/neg" dance. LOG=y BUG=v8:3151 R=bmeurer@chromium.org Review URL: https://codereview.chromium.org/166793002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19434 ce2b1a6d-e550-0410-aec6-3dcde31c8c00	2014-02-18 10:45:27 +00:00
jkummerow@chromium.org	dea98eee53	Fix a bug in Div when all uses are truncating ... Refine the related test cases to cover truncating cases BUG= R=jkummerow@chromium.org Review URL: https://codereview.chromium.org/22964004 Patch from Weiliang Lin <weiliang.lin2@gmail.com>. git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16249 ce2b1a6d-e550-0410-aec6-3dcde31c8c00	2013-08-20 13:57:01 +00:00
yangguo@chromium.org	c70a0f9334	Improve integer division on IA32 and X64 ... If the divisor is a Power-of-2 constant, we could use shifts instead of the expensive idiv instructions, which also loose the register constraints. Review URL: https://chromiumcodereview.appspot.com/11478043 Patch from Yuqiang Xian <yuqiang.xian@intel.com>. git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13178 ce2b1a6d-e550-0410-aec6-3dcde31c8c00	2012-12-10 11:02:22 +00:00