https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113576
--- Comment #41 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Hongtao Liu from comment #38)
> > I think we should also mask off the upper bits of variable mask?
> >
> > notl %esi
> > orl %esi, %edi
> > notl %edi
> > andl $15, %edi
> > je .L3
>
> with -mbmi, it's
>
> andn %esi, %edi, %edi
> andl $15, %edi
> je .L3
Well, yes, the discussion in this bug was whether to do this at consumers
(that's sth new) or with all mask operations (that's how we handle
bit-precision integer operations, so it might be relatively easy to
do that - specifically spot the places eventually needing adjustment).
There's do_store_flag to fixup for uses not in branches and
do_compare_and_jump for conditional jumps.
Note the AND is removed by combine if I add it:
Successfully matched this instruction:
(set (reg:CCZ 17 flags)
(compare:CCZ (and:HI (not:HI (subreg:HI (reg:QI 102 [ tem_3 ]) 0))
(const_int 15 [0xf]))
(const_int 0 [0])))
(*testhi_not)
- 9: {r103:QI=r102:QI&0xf;clobber flags:CC;}
+ REG_DEAD r99:QI
+ 9: NOTE_INSN_DELETED
+ 12: flags:CCZ=cmp(~r102:QI#0&0xf,0)
REG_DEAD r102:QI
- REG_UNUSED flags:CC
- 12: flags:CCZ=cmp(r103:QI,0xf)
- REG_DEAD r103:QI
and we get
foo:
.LFB0:
.cfi_startproc
notl %esi
orl %esi, %edi
notl %edi
testb $15, %dil
je .L6
ret
which I'm not sure is OK?
diff --git a/gcc/dojump.cc b/gcc/dojump.cc
index e2d2b3cb111..784707c1e55 100644
--- a/gcc/dojump.cc
+++ b/gcc/dojump.cc
@@ -1266,6 +1266,7 @@ do_compare_and_jump (tree treeop0, tree treeop1, enum
rtx_code signed_code,
machine_mode mode;
int unsignedp;
enum rtx_code code;
+ unsigned HOST_WIDE_INT nunits;
/* Don't crash if the comparison was erroneous. */
op0 = expand_normal (treeop0);
@@ -1308,6 +1309,18 @@ do_compare_and_jump (tree treeop0, tree treeop1, enum
rtx_code signed_code,
emit_insn (targetm.gen_canonicalize_funcptr_for_compare (new_op1, op1));
op1 = new_op1;
}
+ else if (VECTOR_BOOLEAN_TYPE_P (type)
+ && mode == QImode
+ && TYPE_VECTOR_SUBPARTS (type).is_constant (&nunits)
+ && nunits < BITS_PER_UNIT)
+ {
+ op0 = expand_binop (mode, and_optab, op0,
+ GEN_INT ((1 << nunits) - 1), NULL_RTX,
+ true, OPTAB_WIDEN);
+ op1 = expand_binop (mode, and_optab, op1,
+ GEN_INT ((1 << nunits) - 1), NULL_RTX,
+ true, OPTAB_WIDEN);
+ }
do_compare_rtx_and_jump (op0, op1, code, unsignedp, treeop0, mode,
((mode == BLKmode)
