Just so there is some record of what I did here -- in order to backport the
gpr strncmp expansion improvement patch to gcc 8 I had to pull in some pieces
of an earlier cleanup patch from June of this year.
I'll get this committed to gcc-8-branch when I'm done with the bootstrap/regtest
on a couple different ppc64 architectures (unless anyone has any objections).
Thanks,
Aaron
2018-11-26 Aaron Sawdey <acsaw...@linux.ibm.com>
Backport from mainline
2018-10-25 Aaron Sawdey <acsaw...@linux.ibm.com>
* config/rs6000/rs6000-string.c (expand_strncmp_gpr_sequence): Change to
a shorter sequence with fewer branches.
(emit_final_str_compare_gpr): Ditto.
Backport from mainline to allow the above code to go in:
2018-06-14 Aaron Sawdey <acsaw...@linux.ibm.com>
* config/rs6000/rs6000-string.c (do_and3, do_and3_mask,
Index: rs6000-string.c
===================================================================
--- rs6000-string.c (revision 266483)
+++ rs6000-string.c (working copy)
@@ -408,6 +408,54 @@
emit_insn (gen_addsi3 (dest, src1, src2));
}
+/* Emit an and of the proper mode for DEST.
+
+ DEST is the destination register for the and.
+ SRC1 is the first and input.
+ SRC2 is the second and input.
+
+ Computes DEST = SRC1&SRC2. */
+static void
+do_and3 (rtx dest, rtx src1, rtx src2)
+{
+ if (GET_MODE (dest) == DImode)
+ emit_insn (gen_anddi3 (dest, src1, src2));
+ else
+ emit_insn (gen_andsi3 (dest, src1, src2));
+}
+
+/* Emit an cmpb of the proper mode for DEST.
+
+ DEST is the destination register for the cmpb.
+ SRC1 is the first input.
+ SRC2 is the second input.
+
+ Computes cmpb of SRC1, SRC2. */
+static void
+do_cmpb3 (rtx dest, rtx src1, rtx src2)
+{
+ if (GET_MODE (dest) == DImode)
+ emit_insn (gen_cmpbdi3 (dest, src1, src2));
+ else
+ emit_insn (gen_cmpbsi3 (dest, src1, src2));
+}
+
+/* Emit a rotl of the proper mode for DEST.
+
+ DEST is the destination register for the and.
+ SRC1 is the first and input.
+ SRC2 is the second and input.
+
+ Computes DEST = SRC1 rotated left by SRC2. */
+static void
+do_rotl3 (rtx dest, rtx src1, rtx src2)
+{
+ if (GET_MODE (dest) == DImode)
+ emit_insn (gen_rotldi3 (dest, src1, src2));
+ else
+ emit_insn (gen_rotlsi3 (dest, src1, src2));
+}
+
/* Generate rtl for a load, shift, and compare of less than a full word.
LOAD_MODE is the machine mode for the loads.
@@ -640,7 +688,7 @@
{
if (GET_MODE_SIZE (GET_MODE (bytes_rtx)) > GET_MODE_SIZE (word_mode))
/* Do not expect length longer than word_mode. */
- return false;
+ return false;
else if (GET_MODE_SIZE (GET_MODE (bytes_rtx)) < GET_MODE_SIZE
(word_mode))
{
bytes_rtx = force_reg (GET_MODE (bytes_rtx), bytes_rtx);
@@ -684,7 +732,7 @@
rtx j;
/* Example of generated code for 35 bytes aligned 1 byte.
-
+
mtctr 8
li 6,0
li 5,8
@@ -712,7 +760,7 @@
popcntd 9,9
subfe 10,10,10
or 9,9,10
-
+
Compiled with -fno-reorder-blocks for clarity. */
/* Structure of what we're going to do:
@@ -955,7 +1003,7 @@
if (!bytes_is_const)
{
/* If we're dealing with runtime length, we have to check if
- it's zero after the loop. When length is known at compile
+ it's zero after the loop. When length is known at compile
time the no-remainder condition is dealt with above. By
doing this after cleanup_label, we also deal with the
case where length is 0 at the start and we bypass the
@@ -1325,7 +1373,7 @@
rtx tmp_reg_src1 = gen_reg_rtx (word_mode);
rtx tmp_reg_src2 = gen_reg_rtx (word_mode);
/* P7/P8 code uses cond for subfc. but P9 uses
- it for cmpld which needs CCUNSmode. */
+ it for cmpld which needs CCUNSmode. */
rtx cond;
if (TARGET_P9_MISC)
cond = gen_reg_rtx (CCUNSmode);
@@ -1578,7 +1626,7 @@
emit_label (convert_label);
/* We need to produce DI result from sub, then convert to target SI
- while maintaining <0 / ==0 / >0 properties. This sequence works:
+ while maintaining <0 / ==0 / >0 properties. This sequence works:
subfc L,A,B
subfe H,H,H
popcntd L,L
@@ -1847,6 +1895,9 @@
rtx tmp_reg_src1 = gen_reg_rtx (word_mode);
rtx tmp_reg_src2 = gen_reg_rtx (word_mode);
+ rtx src1_addr = force_reg (Pmode, XEXP (orig_src1, 0));
+ rtx src2_addr = force_reg (Pmode, XEXP (orig_src2, 0));
+
/* Generate sequence of ld/ldbrx, cmpb to compare out
to the length specified. */
unsigned HOST_WIDE_INT bytes_to_compare = compare_length;
@@ -1853,12 +1904,9 @@
while (bytes_to_compare > 0)
{
/* Compare sequence:
- check each 8B with: ld/ld cmpd bne
- If equal, use rldicr/cmpb to check for zero byte.
+ check each 8B with: ld/ld/cmpb/cmpb/orc./bne
+
cleanup code at end:
- cmpb get byte that differs
- cmpb look for zero byte
- orc combine
cntlzd get bit of first zero/diff byte
subfic convert for rldcl use
rldcl rldcl extract diff/zero byte
@@ -1895,64 +1943,54 @@
rid of the extra bytes. */
cmp_bytes = bytes_to_compare;
- src1 = adjust_address (orig_src1, load_mode, offset);
- src2 = adjust_address (orig_src2, load_mode, offset);
+ rtx offset_rtx;
+ if (BYTES_BIG_ENDIAN || TARGET_AVOID_XFORM)
+ offset_rtx = GEN_INT (offset);
+ else
+ {
+ offset_rtx = gen_reg_rtx (Pmode);
+ emit_move_insn (offset_rtx, GEN_INT (offset));
+ }
+ rtx addr1 = gen_rtx_PLUS (Pmode, src1_addr, offset_rtx);
+ rtx addr2 = gen_rtx_PLUS (Pmode, src2_addr, offset_rtx);
+ do_load_for_compare_from_addr (load_mode, tmp_reg_src1, addr1,
orig_src1);
+ do_load_for_compare_from_addr (load_mode, tmp_reg_src2, addr2,
orig_src2);
- if (!REG_P (XEXP (src1, 0)))
- {
- rtx src1_reg = copy_addr_to_reg (XEXP (src1, 0));
- src1 = replace_equiv_address (src1, src1_reg);
- }
- set_mem_size (src1, load_mode_size);
-
- if (!REG_P (XEXP (src2, 0)))
- {
- rtx src2_reg = copy_addr_to_reg (XEXP (src2, 0));
- src2 = replace_equiv_address (src2, src2_reg);
- }
- set_mem_size (src2, load_mode_size);
-
- do_load_for_compare (tmp_reg_src1, src1, load_mode);
- do_load_for_compare (tmp_reg_src2, src2, load_mode);
-
/* We must always left-align the data we read, and
clear any bytes to the right that are beyond the string.
Otherwise the cmpb sequence won't produce the correct
- results. The beginning of the compare will be done
- with word_mode so will not have any extra shifts or
- clear rights. */
+ results. However if there is only one byte left, we
+ can just subtract to get the final result so the shifts
+ and clears are not needed. */
- if (load_mode_size < word_mode_size)
- {
- /* Rotate left first. */
- rtx sh = GEN_INT (BITS_PER_UNIT * (word_mode_size - load_mode_size));
- if (word_mode == DImode)
- {
- emit_insn (gen_rotldi3 (tmp_reg_src1, tmp_reg_src1, sh));
- emit_insn (gen_rotldi3 (tmp_reg_src2, tmp_reg_src2, sh));
- }
- else
- {
- emit_insn (gen_rotlsi3 (tmp_reg_src1, tmp_reg_src1, sh));
- emit_insn (gen_rotlsi3 (tmp_reg_src2, tmp_reg_src2, sh));
- }
- }
+ unsigned HOST_WIDE_INT remain = bytes_to_compare - cmp_bytes;
- if (cmp_bytes < word_mode_size)
+ /* Loading just a single byte is a special case. If we are
+ loading more than that, we have to check whether we are
+ looking at the entire chunk of data. If not, rotate left and
+ clear right so that bytes we aren't supposed to look at are
+ zeroed, and the first byte we are supposed to compare is
+ leftmost. */
+
+ if (load_mode_size != 1)
{
- /* Now clear right. This plus the rotate can be
- turned into a rldicr instruction. */
- HOST_WIDE_INT mb = BITS_PER_UNIT * (word_mode_size - cmp_bytes);
- rtx mask = GEN_INT (HOST_WIDE_INT_M1U << mb);
- if (word_mode == DImode)
+ if (load_mode_size < word_mode_size)
{
- emit_insn (gen_anddi3_mask (tmp_reg_src1, tmp_reg_src1, mask));
- emit_insn (gen_anddi3_mask (tmp_reg_src2, tmp_reg_src2, mask));
+ /* Rotate left first. */
+ rtx sh = GEN_INT (BITS_PER_UNIT
+ * (word_mode_size - load_mode_size));
+ do_rotl3 (tmp_reg_src1, tmp_reg_src1, sh);
+ do_rotl3 (tmp_reg_src2, tmp_reg_src2, sh);
}
- else
+
+ if (cmp_bytes < word_mode_size)
{
- emit_insn (gen_andsi3_mask (tmp_reg_src1, tmp_reg_src1, mask));
- emit_insn (gen_andsi3_mask (tmp_reg_src2, tmp_reg_src2, mask));
+ /* Now clear right. This plus the rotate can be
+ turned into a rldicr instruction. */
+ HOST_WIDE_INT mb = BITS_PER_UNIT * (word_mode_size - cmp_bytes);
+ rtx mask = GEN_INT (HOST_WIDE_INT_M1U << mb);
+ do_and3 (tmp_reg_src1, tmp_reg_src1, mask);
+ do_and3 (tmp_reg_src2, tmp_reg_src2, mask);
}
}
@@ -1967,8 +2005,6 @@
A == B: branch to result 0.
A != B: cleanup code to compute result. */
- unsigned HOST_WIDE_INT remain = bytes_to_compare - cmp_bytes;
-
rtx dst_label;
if (remain > 0 || equality_compare_rest)
{
@@ -1982,69 +2018,89 @@
/* Branch to end and produce result of 0. */
dst_label = final_move_label;
- rtx lab_ref = gen_rtx_LABEL_REF (VOIDmode, dst_label);
- rtx cond = gen_reg_rtx (CCmode);
+ if (load_mode_size == 1)
+ {
+ /* Special case for comparing just single byte. */
+ if (equality_compare_rest)
+ {
+ /* Use subf./bne to branch to final_move_label if the
+ byte differs, otherwise fall through to the strncmp
+ call. We must also check for a zero byte here as we
+ must not make the library call if this is the end of
+ the string. */
- /* Always produce the 0 result, it is needed if
- cmpb finds a 0 byte in this chunk. */
- rtx tmp = gen_rtx_MINUS (word_mode, tmp_reg_src1, tmp_reg_src2);
- rs6000_emit_dot_insn (result_reg, tmp, 1, cond);
+ rtx lab_ref = gen_rtx_LABEL_REF (VOIDmode, final_move_label);
+ rtx cond = gen_reg_rtx (CCmode);
+ rtx diff_rtx = gen_rtx_MINUS (word_mode,
+ tmp_reg_src1, tmp_reg_src2);
+ rs6000_emit_dot_insn (result_reg, diff_rtx, 2, cond);
+ rtx cmp_rtx = gen_rtx_NE (VOIDmode, cond, const0_rtx);
- rtx cmp_rtx;
- if (remain == 0 && !equality_compare_rest)
- cmp_rtx = gen_rtx_EQ (VOIDmode, cond, const0_rtx);
- else
- cmp_rtx = gen_rtx_NE (VOIDmode, cond, const0_rtx);
+ rtx ifelse = gen_rtx_IF_THEN_ELSE (VOIDmode, cmp_rtx,
+ lab_ref, pc_rtx);
+ rtx j = emit_jump_insn (gen_rtx_SET (pc_rtx, ifelse));
+ JUMP_LABEL (j) = final_move_label;
+ LABEL_NUSES (final_move_label) += 1;
- rtx ifelse = gen_rtx_IF_THEN_ELSE (VOIDmode, cmp_rtx,
- lab_ref, pc_rtx);
- rtx j = emit_jump_insn (gen_rtx_SET (pc_rtx, ifelse));
- JUMP_LABEL (j) = dst_label;
- LABEL_NUSES (dst_label) += 1;
+ /* Check for zero byte here before fall through to
+ library call. This catches the case where the
+ strings are equal and end in a zero byte at this
+ position. */
- if (remain > 0 || equality_compare_rest)
- {
- /* Generate a cmpb to test for a 0 byte and branch
- to final result if found. */
- rtx cmpb_zero = gen_reg_rtx (word_mode);
- rtx lab_ref_fin = gen_rtx_LABEL_REF (VOIDmode, final_move_label);
- rtx condz = gen_reg_rtx (CCmode);
- rtx zero_reg = gen_reg_rtx (word_mode);
- if (word_mode == SImode)
- {
- emit_insn (gen_movsi (zero_reg, GEN_INT (0)));
- emit_insn (gen_cmpbsi3 (cmpb_zero, tmp_reg_src1, zero_reg));
- if (cmp_bytes < word_mode_size)
- {
- /* Don't want to look at zero bytes past end. */
- HOST_WIDE_INT mb =
- BITS_PER_UNIT * (word_mode_size - cmp_bytes);
- rtx mask = GEN_INT (HOST_WIDE_INT_M1U << mb);
- emit_insn (gen_andsi3_mask (cmpb_zero, cmpb_zero, mask));
- }
+ rtx cond0 = gen_reg_rtx (CCmode);
+ emit_move_insn (cond0, gen_rtx_COMPARE (CCmode, tmp_reg_src1,
+ const0_rtx));
+
+ rtx cmp0eq_rtx = gen_rtx_EQ (VOIDmode, cond0, const0_rtx);
+
+ rtx ifelse0 = gen_rtx_IF_THEN_ELSE (VOIDmode, cmp0eq_rtx,
+ lab_ref, pc_rtx);
+ rtx j0 = emit_jump_insn (gen_rtx_SET (pc_rtx, ifelse0));
+ JUMP_LABEL (j0) = final_move_label;
+ LABEL_NUSES (final_move_label) += 1;
}
else
{
- emit_insn (gen_movdi (zero_reg, GEN_INT (0)));
- emit_insn (gen_cmpbdi3 (cmpb_zero, tmp_reg_src1, zero_reg));
- if (cmp_bytes < word_mode_size)
- {
- /* Don't want to look at zero bytes past end. */
- HOST_WIDE_INT mb =
- BITS_PER_UNIT * (word_mode_size - cmp_bytes);
- rtx mask = GEN_INT (HOST_WIDE_INT_M1U << mb);
- emit_insn (gen_anddi3_mask (cmpb_zero, cmpb_zero, mask));
- }
+ /* This is the last byte to be compared so we can use
+ subf to compute the final result and branch
+ unconditionally to final_move_label. */
+
+ do_sub3 (result_reg, tmp_reg_src1, tmp_reg_src2);
+
+ rtx fin_ref = gen_rtx_LABEL_REF (VOIDmode, final_move_label);
+ rtx j = emit_jump_insn (gen_rtx_SET (pc_rtx, fin_ref));
+ JUMP_LABEL (j) = final_move_label;
+ LABEL_NUSES (final_move_label) += 1;
+ emit_barrier ();
}
+ }
+ else
+ {
+ rtx cmpb_zero = gen_reg_rtx (word_mode);
+ rtx cmpb_diff = gen_reg_rtx (word_mode);
+ rtx zero_reg = gen_reg_rtx (word_mode);
+ rtx lab_ref = gen_rtx_LABEL_REF (VOIDmode, dst_label);
+ rtx cond = gen_reg_rtx (CCmode);
- emit_move_insn (condz, gen_rtx_COMPARE (CCmode, cmpb_zero, zero_reg));
- rtx cmpnz_rtx = gen_rtx_NE (VOIDmode, condz, const0_rtx);
- rtx ifelse = gen_rtx_IF_THEN_ELSE (VOIDmode, cmpnz_rtx,
- lab_ref_fin, pc_rtx);
- rtx j2 = emit_jump_insn (gen_rtx_SET (pc_rtx, ifelse));
- JUMP_LABEL (j2) = final_move_label;
- LABEL_NUSES (final_move_label) += 1;
+ emit_move_insn (zero_reg, GEN_INT (0));
+ do_cmpb3 (cmpb_diff, tmp_reg_src1, tmp_reg_src2);
+ do_cmpb3 (cmpb_zero, tmp_reg_src1, zero_reg);
+ rtx not_diff = gen_rtx_NOT (word_mode, cmpb_diff);
+ rtx orc_rtx = gen_rtx_IOR (word_mode, not_diff, cmpb_zero);
+ rs6000_emit_dot_insn (result_reg, orc_rtx, 2, cond);
+
+ rtx cmp_rtx;
+ if (remain == 0 && !equality_compare_rest)
+ cmp_rtx = gen_rtx_EQ (VOIDmode, cond, const0_rtx);
+ else
+ cmp_rtx = gen_rtx_NE (VOIDmode, cond, const0_rtx);
+
+ rtx ifelse = gen_rtx_IF_THEN_ELSE (VOIDmode, cmp_rtx,
+ lab_ref, pc_rtx);
+ rtx j = emit_jump_insn (gen_rtx_SET (pc_rtx, ifelse));
+ JUMP_LABEL (j) = dst_label;
+ LABEL_NUSES (dst_label) += 1;
}
offset += cmp_bytes;
@@ -2106,9 +2162,6 @@
byte and generates the final result, taking into account
zero bytes:
- cmpb cmpb_result1, src1, src2
- cmpb cmpb_result2, src1, zero
- orc cmpb_result1, cmp_result1, cmpb_result2
cntlzd get bit of first zero/diff byte
addi convert for rldcl use
rldcl rldcl extract diff/zero byte
@@ -2115,10 +2168,7 @@
subf subtract for final result
*/
- rtx cmpb_diff = gen_reg_rtx (word_mode);
- rtx cmpb_zero = gen_reg_rtx (word_mode);
rtx rot_amt = gen_reg_rtx (word_mode);
- rtx zero_reg = gen_reg_rtx (word_mode);
rtx rot1_1 = gen_reg_rtx (word_mode);
rtx rot1_2 = gen_reg_rtx (word_mode);
@@ -2127,12 +2177,7 @@
if (word_mode == SImode)
{
- emit_insn (gen_cmpbsi3 (cmpb_diff, tmp_reg_src1, tmp_reg_src2));
- emit_insn (gen_movsi (zero_reg, GEN_INT (0)));
- emit_insn (gen_cmpbsi3 (cmpb_zero, tmp_reg_src1, zero_reg));
- emit_insn (gen_one_cmplsi2 (cmpb_diff,cmpb_diff));
- emit_insn (gen_iorsi3 (cmpb_diff, cmpb_diff, cmpb_zero));
- emit_insn (gen_clzsi2 (rot_amt, cmpb_diff));
+ emit_insn (gen_clzsi2 (rot_amt, result_reg));
emit_insn (gen_addsi3 (rot_amt, rot_amt, GEN_INT (8)));
emit_insn (gen_rotlsi3 (rot1_1, tmp_reg_src1,
gen_lowpart (SImode, rot_amt)));
@@ -2144,12 +2189,7 @@
}
else
{
- emit_insn (gen_cmpbdi3 (cmpb_diff, tmp_reg_src1, tmp_reg_src2));
- emit_insn (gen_movdi (zero_reg, GEN_INT (0)));
- emit_insn (gen_cmpbdi3 (cmpb_zero, tmp_reg_src1, zero_reg));
- emit_insn (gen_one_cmpldi2 (cmpb_diff,cmpb_diff));
- emit_insn (gen_iordi3 (cmpb_diff, cmpb_diff, cmpb_zero));
- emit_insn (gen_clzdi2 (rot_amt, cmpb_diff));
+ emit_insn (gen_clzdi2 (rot_amt, result_reg));
emit_insn (gen_adddi3 (rot_amt, rot_amt, GEN_INT (8)));
emit_insn (gen_rotldi3 (rot1_1, tmp_reg_src1,
gen_lowpart (SImode, rot_amt)));
--
Aaron Sawdey, Ph.D. acsaw...@linux.vnet.ibm.com
050-2/C113 (507) 253-7520 home: 507/263-0782
IBM Linux Technology Center - PPC Toolchain
