https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108803
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The change then would be
--- gcc/optabs.cc.jj 2023-01-02 09:32:53.309838465 +0100
+++ gcc/optabs.cc 2023-02-16 19:33:14.583883584 +0100
@@ -507,7 +507,7 @@ expand_subword_shift (scalar_int_mode op
rtx outof_input, rtx into_input, rtx op1,
rtx outof_target, rtx into_target,
int unsignedp, enum optab_methods methods,
- unsigned HOST_WIDE_INT shift_mask)
+ unsigned HOST_WIDE_INT shift_mask, bool mask_count)
{
optab reverse_unsigned_shift, unsigned_shift;
rtx tmp, carries;
@@ -526,6 +526,23 @@ expand_subword_shift (scalar_int_mode op
tmp = simplify_expand_binop (op1_mode, sub_optab, tmp, op1,
0, true, methods);
}
+ else if (mask_count)
+ {
+ /* When called from expand_doubleword_shift_condmove with shift_mask 0,
+ we need to mask the shift count (and on some targets have that later
+ be combined with shifts into a single instruction). In that case
+ we can avoid the separate shift by 1 and another by
+ (BITS_PER_WORD - 1) - op1 and can just do one shift by
+ -op1 & (BITS_PER_WORD - 1). */
+ carries = outof_input;
+ tmp = expand_unop (op1_mode, neg_optab, op1, 0, false);
+ rtx tmp2 = immed_wide_int_const (wi::shwi (BITS_PER_WORD - 1,
+ op1_mode), op1_mode);
+ tmp = simplify_expand_binop (op1_mode, and_optab, tmp, tmp2, 0, true,
+ methods);
+ op1 = simplify_expand_binop (op1_mode, and_optab, op1, tmp2, 0, true,
+ methods);
+ }
else
{
/* We must avoid shifting by BITS_PER_WORD bits since that is either
@@ -596,6 +613,15 @@ expand_doubleword_shift_condmove (scalar
{
rtx outof_superword, into_superword;
+ if (shift_mask < BITS_PER_WORD - 1)
+ {
+ rtx tmp = immed_wide_int_const (wi::shwi (BITS_PER_WORD - 1, op1_mode),
+ op1_mode);
+ superword_op1
+ = simplify_expand_binop (op1_mode, and_optab, superword_op1, tmp,
+ 0, true, methods);
+ }
+
/* Put the superword version of the output into OUTOF_SUPERWORD and
INTO_SUPERWORD. */
outof_superword = outof_target != 0 ? gen_reg_rtx (word_mode) : 0;
@@ -621,7 +647,8 @@ expand_doubleword_shift_condmove (scalar
if (!expand_subword_shift (op1_mode, binoptab,
outof_input, into_input, subword_op1,
outof_target, into_target,
- unsignedp, methods, shift_mask))
+ unsignedp, methods, shift_mask,
+ shift_mask < BITS_PER_WORD - 1))
return false;
/* Select between them. Do the INTO half first because INTO_SUPERWORD
@@ -742,7 +769,7 @@ expand_doubleword_shift (scalar_int_mode
return expand_subword_shift (op1_mode, binoptab,
outof_input, into_input, op1,
outof_target, into_target,
- unsignedp, methods, shift_mask);
+ unsignedp, methods, shift_mask, false);
}
/* Try using conditional moves to generate straight-line code. */
@@ -781,7 +808,7 @@ expand_doubleword_shift (scalar_int_mode
if (!expand_subword_shift (op1_mode, binoptab,
outof_input, into_input, op1,
outof_target, into_target,
- unsignedp, methods, shift_mask))
+ unsignedp, methods, shift_mask, false))
return false;
emit_label (done_label);
or so and emits one fewer instruction for foo and bar as before. But somehow
the #c0 testcase with it aborts again, so something is not right...
