On 03/04/2016 06:27 PM, Bernd Schmidt wrote:
On 03/04/2016 06:14 PM, Patrick Palka wrote:
I just quickly tested building the generated insn-attrtab.c with and
without the patch using my host gcc 5.3 compiler and the .s output is
not the same.
Hmm, looking at the 003t.original dump it looks like there are
differences in SAVE_EXPRs. Indeed we seem to generate different code for
int at;
int foo ()
{
if (at == 2 || at == 4 || at == 7)
return 1;
return 0;
}
int bar ()
{
if (at == 2 || (at == 4 || at == 7))
return 1;
return 0;
}
Ahh... it's not just different placement of SAVE_EXPRs, it's actually a
case of TRUTH_ORIF_EXPR vs. TRUTH_OR_EXPR (the distinction is invisible
in the dumps), the latter being created by fold_range_test. That's a bit
of a broken optimization what with its inability to see more than two
comparisons at a time... we convert one ORIF per function, but a
different one.
Bernd
