throughout the computation, we can get correct behavior by replacing
M with M' as follows:
- { M[i+8]+8 : i < 8, M[i+8] in [0,7] U [16,23]
- M'[i] = { M[i+8]-8 : i < 8, M[i+8] in [8,15] U [24,31]
- { M[i-8]+8 : i >= 8, M[i-8] in [0,7] U [16,23]
- { M[i-8]-8 : i >= 8, M[i-8] in [8,15] U [24,31]
+ M'[i] = { (M[i]+8)%16 : M[i] in [0,15]
+ { ((M[i]+8)%16)+16 : M[i] in [16,31]
This seems promising at first, since we are just replacing one mask
with another. But certain masks are preferable to others. If M
mask to be produced by an UNSPEC_LVSL, in which case the mask
cannot be known at compile time. In such a case we would have to
generate several instructions to compute M' as above at run time,
- and a cost model is needed again. */
+ and a cost model is needed again.
+
+ However, when the mask M for an UNSPEC_VPERM is loaded from the
+ constant pool, we can replace M with M' as above at no cost
+ beyond adding a constant pool entry. */
/* This is based on the union-find logic in web.c. web_entry_base is
defined in df.h. */
SH_EXTRACT,
SH_SPLAT,
SH_XXPERMDI,
- SH_CONCAT
+ SH_CONCAT,
+ SH_VPERM
};
/* Union INSN with all insns containing definitions that reach USE.
return 1;
}
+/* Return TRUE if insn is a swap fed by a load from the constant pool. */
+static bool
+const_load_sequence_p (swap_web_entry *insn_entry, rtx insn)
+{
+ unsigned uid = INSN_UID (insn);
+ if (!insn_entry[uid].is_swap || insn_entry[uid].is_load)
+ return false;
+
+ /* Find the unique use in the swap and locate its def. If the def
+ isn't unique, punt. */
+ struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+ df_ref use;
+ FOR_EACH_INSN_INFO_USE (use, insn_info)
+ {
+ struct df_link *def_link = DF_REF_CHAIN (use);
+ if (!def_link || def_link->next)
+ return false;
+
+ rtx def_insn = DF_REF_INSN (def_link->ref);
+ unsigned uid2 = INSN_UID (def_insn);
+ if (!insn_entry[uid2].is_load || !insn_entry[uid2].is_swap)
+ return false;
+
+ rtx body = PATTERN (def_insn);
+ if (GET_CODE (body) != SET
+ || GET_CODE (SET_SRC (body)) != VEC_SELECT
+ || GET_CODE (XEXP (SET_SRC (body), 0)) != MEM)
+ return false;
+
+ rtx mem = XEXP (SET_SRC (body), 0);
+ rtx base_reg = XEXP (mem, 0);
+
+ df_ref base_use;
+ insn_info = DF_INSN_INFO_GET (def_insn);
+ FOR_EACH_INSN_INFO_USE (base_use, insn_info)
+ {
+ if (!rtx_equal_p (DF_REF_REG (base_use), base_reg))
+ continue;
+
+ struct df_link *base_def_link = DF_REF_CHAIN (base_use);
+ if (!base_def_link || base_def_link->next)
+ return false;
+
+ rtx tocrel_insn = DF_REF_INSN (base_def_link->ref);
+ rtx tocrel_body = PATTERN (tocrel_insn);
+ rtx base, offset;
+ if (GET_CODE (tocrel_body) != SET)
+ return false;
+ if (!toc_relative_expr_p (SET_SRC (tocrel_body), false))
+ return false;
+ split_const (XVECEXP (tocrel_base, 0, 0), &base, &offset);
+ if (GET_CODE (base) != SYMBOL_REF || !CONSTANT_POOL_ADDRESS_P (base))
+ return false;
+ }
+ }
+ return true;
+}
+
/* Return 1 iff OP is an operand that will not be affected by having
vector doublewords swapped in memory. */
static unsigned int
return 1;
}
+ /* An UNSPEC_VPERM is ok if the mask operand is loaded from the
+ constant pool. */
+ if (GET_CODE (body) == SET
+ && GET_CODE (SET_SRC (body)) == UNSPEC
+ && XINT (SET_SRC (body), 1) == UNSPEC_VPERM
+ && XVECLEN (SET_SRC (body), 0) == 3
+ && GET_CODE (XVECEXP (SET_SRC (body), 0, 2)) == REG)
+ {
+ rtx mask_reg = XVECEXP (SET_SRC (body), 0, 2);
+ struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+ df_ref use;
+ FOR_EACH_INSN_INFO_USE (use, insn_info)
+ if (rtx_equal_p (DF_REF_REG (use), mask_reg))
+ {
+ struct df_link *def_link = DF_REF_CHAIN (use);
+ /* Punt if multiple definitions for this reg. */
+ if (def_link && !def_link->next &&
+ const_load_sequence_p (insn_entry,
+ DF_REF_INSN (def_link->ref)))
+ {
+ *special = SH_VPERM;
+ return 1;
+ }
+ }
+ }
+
/* Otherwise check the operands for vector lane violations. */
return rtx_is_swappable_p (body, special);
}
fprintf (dump_file, "Reversing inputs for concat %d\n", INSN_UID (insn));
}
+/* Given an UNSPEC_VPERM insn, modify the mask loaded from the
+ constant pool to reflect swapped doublewords. */
+static void
+adjust_vperm (rtx_insn *insn)
+{
+ /* We previously determined that the UNSPEC_VPERM was fed by a
+ swap of a swapping load of a TOC-relative constant pool symbol.
+ Find the MEM in the swapping load and replace it with a MEM for
+ the adjusted mask constant. */
+ rtx set = PATTERN (insn);
+ rtx mask_reg = XVECEXP (SET_SRC (set), 0, 2);
+
+ /* Find the swap. */
+ struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+ df_ref use;
+ rtx_insn *swap_insn = 0;
+ FOR_EACH_INSN_INFO_USE (use, insn_info)
+ if (rtx_equal_p (DF_REF_REG (use), mask_reg))
+ {
+ struct df_link *def_link = DF_REF_CHAIN (use);
+ gcc_assert (def_link && !def_link->next);
+ swap_insn = DF_REF_INSN (def_link->ref);
+ break;
+ }
+ gcc_assert (swap_insn);
+
+ /* Find the load. */
+ insn_info = DF_INSN_INFO_GET (swap_insn);
+ rtx_insn *load_insn = 0;
+ FOR_EACH_INSN_INFO_USE (use, insn_info)
+ {
+ struct df_link *def_link = DF_REF_CHAIN (use);
+ gcc_assert (def_link && !def_link->next);
+ load_insn = DF_REF_INSN (def_link->ref);
+ break;
+ }
+ gcc_assert (load_insn);
+
+ /* Find the TOC-relative symbol access. */
+ insn_info = DF_INSN_INFO_GET (load_insn);
+ rtx_insn *tocrel_insn = 0;
+ FOR_EACH_INSN_INFO_USE (use, insn_info)
+ {
+ struct df_link *def_link = DF_REF_CHAIN (use);
+ gcc_assert (def_link && !def_link->next);
+ tocrel_insn = DF_REF_INSN (def_link->ref);
+ break;
+ }
+ gcc_assert (tocrel_insn);
+
+ /* Find the embedded CONST_VECTOR. We have to call toc_relative_expr_p
+ to set tocrel_base; otherwise it would be unnecessary as we've
+ already established it will return true. */
+ rtx base, offset;
+ if (!toc_relative_expr_p (SET_SRC (PATTERN (tocrel_insn)), false))
+ gcc_unreachable ();
+ split_const (XVECEXP (tocrel_base, 0, 0), &base, &offset);
+ rtx const_vector = get_pool_constant (base);
+ gcc_assert (GET_CODE (const_vector) == CONST_VECTOR);
+
+ /* Create an adjusted mask from the initial mask. */
+ unsigned int new_mask[16], i, val;
+ for (i = 0; i < 16; ++i) {
+ val = INTVAL (XVECEXP (const_vector, 0, i));
+ if (val < 16)
+ new_mask[i] = (val + 8) % 16;
+ else
+ new_mask[i] = ((val + 8) % 16) + 16;
+ }
+
+ /* Create a new CONST_VECTOR and a MEM that references it. */
+ rtx vals = gen_rtx_PARALLEL (V16QImode, rtvec_alloc (16));
+ for (i = 0; i < 16; ++i)
+ XVECEXP (vals, 0, i) = GEN_INT (new_mask[i]);
+ rtx new_const_vector = gen_rtx_CONST_VECTOR (V16QImode, XVEC (vals, 0));
+ rtx new_mem = force_const_mem (V16QImode, new_const_vector);
+ /* This gives us a MEM whose base operand is a SYMBOL_REF, which we
+ can't recognize. Force the SYMBOL_REF into a register. */
+ if (!REG_P (XEXP (new_mem, 0))) {
+ rtx base_reg = force_reg (Pmode, XEXP (new_mem, 0));
+ XEXP (new_mem, 0) = base_reg;
+ /* Move the newly created insn ahead of the load insn. */
+ rtx_insn *force_insn = get_last_insn ();
+ remove_insn (force_insn);
+ rtx_insn *before_load_insn = PREV_INSN (load_insn);
+ add_insn_after (force_insn, before_load_insn, BLOCK_FOR_INSN (load_insn));
+ df_insn_rescan (before_load_insn);
+ df_insn_rescan (force_insn);
+ }
+
+ /* Replace the MEM in the load instruction and rescan it. */
+ XEXP (SET_SRC (PATTERN (load_insn)), 0) = new_mem;
+ INSN_CODE (load_insn) = -1; /* Force re-recognition. */
+ df_insn_rescan (load_insn);
+
+ if (dump_file)
+ fprintf (dump_file, "Adjusting mask for vperm %d\n", INSN_UID (insn));
+}
+
/* The insn described by INSN_ENTRY[I] can be swapped, but only
with special handling. Take care of that here. */
static void
/* Reverse the order of a concatenation operation. */
adjust_concat (insn);
break;
+ case SH_VPERM:
+ /* Change the mask loaded from the constant pool for a VPERM. */
+ adjust_vperm (insn);
+ break;
}
}
fputs ("special:xxpermdi ", dump_file);
else if (insn_entry[i].special_handling == SH_CONCAT)
fputs ("special:concat ", dump_file);
+ else if (insn_entry[i].special_handling == SH_VPERM)
+ fputs ("special:vperm ", dump_file);
}
if (insn_entry[i].web_not_optimizable)
fputs ("unoptimizable ", dump_file);
projects / gcc.git / commitdiff