http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46939
Summary: http://blog.regehr.org/archives/320 example 6
Product: gcc
Version: 4.6.0
URL: http://blog.regehr.org/archives/320
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ada
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ja...@gcc.gnu.org
CC: hubi...@gcc.gnu.org
The reason we don't expand / 10 using a multiplication is because gcc thinks it
happens in cold code.
In *.optimized we have:
# BLOCK 5 freq:9999
# PRED: 4 [100.0%] (fallthru,exec) 2 [33.3%] (exec)
# PT = nonlocal
# strD.1584_1 = PHI <strD.1584_17(4), strD.1584_12(D)(2)>
# signD.1590_5 = PHI <signD.1590_4(4), 0(2)>
<L39>:
str.0D.2703_18 = (long unsigned intD.4) strD.1584_1;
end.1D.2704_19 = (long unsigned intD.4) endD.1592_13;
if (str.0D.2703_18 < end.1D.2704_19)
goto <bb 6>;
else
goto <bb 22>;
# SUCC: 6 [4.0%] (true,exec) 22 [96.0%] (false,exec)
# BLOCK 6 freq:400
# PRED: 5 [4.0%] (true,exec)
# VUSE <.MEMD.2753_65(D)>
D.2701_20 = *strD.1584_1;
if (D.2701_20 > 48)
goto <bb 7>;
else
goto <bb 22>;
# SUCC: 7 [4.0%] (true,exec) 22 [96.0%] (false,exec)
# BLOCK 7 freq:16
# PRED: 6 [4.0%] (true,exec)
if (D.2701_20 <= 57)
goto <bb 8>;
else
goto <bb 22>;
# SUCC: 8 [4.0%] (true,exec) 22 [96.0%] (false,exec)
...
# BLOCK 15 freq:6
# PRED: 14 [96.0%] (true,exec)
D.2735_44 = (long intD.2) digitD.1591_43;
D.2736_45 = 9223372036854775807 - D.2735_44;
D.2737_46 = D.2736_45 / 10;
if (ctx_valueD.1589_3 <= D.2737_46)
goto <bb 16>;
else
goto <bb 22>;
# SUCC: 16 [96.0%] (true,exec) 22 [4.0%] (false,exec)
while ((unsigned long) str < (unsigned long) end) is a loop, not sure why we
predict the loop header to terminate immediately, and both the >= 48 and <= 57
tests have return -1; in the other branch, so it is also strange to see them
predicted so unlikely. Honza?
