| Message ID | CAO2gOZWhfyPKEmaEMBTap3e1RTAfsi6++J=BgY+C8gcmFfRT4w@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
Is it possible to add a test case? David On Wed, Jan 22, 2014 at 6:08 PM, Dehao Chen <dehao@google.com> wrote: > During floating point comparison, compiler inserts conditional jumps > to check if the operand is NAN. These type of checks are normally > false. However, compiler sets the probability the same as the original > float-compare conditional jump. This patch sets the probability of > these conditional jumps as 1%. > > Bootstrapped and passed regression test. > > OK for trunk? > > Thanks, > Dehao > > gcc/ChangeLog: > 2014-01-22 Dehao Chen <dehao@google.com> > > * dojump.c (do_compare_rtx_and_jump): Sets correct probability for > compiler inserted conditional jumps for NAN float check. > > Index: gcc/dojump.c > =================================================================== > --- gcc/dojump.c (revision 206945) > +++ gcc/dojump.c (working copy) > @@ -1103,6 +1103,11 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum rt > > else > { > + int first_prob = prob; > + if (first_code == UNORDERED) > + first_prob = REG_BR_PROB_BASE / 100; > + else if (first_code == ORDERED) > + first_prob = REG_BR_PROB_BASE - REG_BR_PROB_BASE / 100; > if (and_them) > { > rtx dest_label; > @@ -1116,11 +1121,13 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum rt > else > dest_label = if_false_label; > do_compare_rtx_and_jump (op0, op1, first_code, > unsignedp, mode, > - size, dest_label, NULL_RTX, prob); > + size, dest_label, NULL_RTX, > + first_prob); > } > else > do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode, > - size, NULL_RTX, if_true_label, prob); > + size, NULL_RTX, if_true_label, > + first_prob); > } > }
Index: gcc/dojump.c =================================================================== --- gcc/dojump.c (revision 206945) +++ gcc/dojump.c (working copy) @@ -1103,6 +1103,11 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum rt else { + int first_prob = prob; + if (first_code == UNORDERED) + first_prob = REG_BR_PROB_BASE / 100; + else if (first_code == ORDERED) + first_prob = REG_BR_PROB_BASE - REG_BR_PROB_BASE / 100; if (and_them) { rtx dest_label; @@ -1116,11 +1121,13 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum rt else dest_label = if_false_label; do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode, - size, dest_label, NULL_RTX, prob); + size, dest_label, NULL_RTX, + first_prob); } else do_compare_rtx_and_jump (op0, op1, first_code, unsignedp, mode, - size, NULL_RTX, if_true_label, prob); + size, NULL_RTX, if_true_label, + first_prob); } }
During floating point comparison, compiler inserts conditional jumps to check if the operand is NAN. These type of checks are normally false. However, compiler sets the probability the same as the original float-compare conditional jump. This patch sets the probability of these conditional jumps as 1%. Bootstrapped and passed regression test. OK for trunk? Thanks, Dehao gcc/ChangeLog: 2014-01-22 Dehao Chen <dehao@google.com> * dojump.c (do_compare_rtx_and_jump): Sets correct probability for compiler inserted conditional jumps for NAN float check.