Sanjay Patel 5a59407f3b [MIPS] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz() ... MIPS32 has instructions for efficient count-leading/trailing-zeros, so this should be considered a cheap operation (and therefore fair game for speculation) for any MIPS32 implementation. The net result of allowing this speculation for the regression tests in this patch is that we get this code: ctlz: jr $ra clz $2, $4 cttz: addiu $1, $4, -1 not $2, $4 and $1, $2, $1 clz $1, $1 addiu $2, $zero, 32 jr $ra subu $2, $2, $1 Instead of: ctlz: beqz $4, $BB0_2 addiu $2, $zero, 32 clz $2, $4 $BB0_2: jr $ra nop cttz: beqz $4, $BB1_2 addiu $2, $zero, 32 addiu $1, $4, -1 not $2, $4 and $1, $2, $1 clz $1, $1 addiu $2, $zero, 32 subu $2, $2, $1 $BB1_2: jr $ra nop See D14469 for the larger motivation. Differential Revision: http://reviews.llvm.org/D14500 llvm-svn: 252755		2015-11-11 17:24:56 +00:00
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cttz-ctlz.ll
lit.local.cfg