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[PATCH, SH] Improve builtin strnlen for small lengths
- From: Christian Bruel <christian dot bruel at st dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Kaz Kojima <kkojima at rr dot iij4u dot or dot jp>
- Date: Fri, 10 Jan 2014 14:18:24 +0100
- Subject: [PATCH, SH] Improve builtin strnlen for small lengths
- Authentication-results: sourceware.org; auth=none
Hello,
This patch unrolls string compare for length < 8 and residual bytes
after the word at a time loops (with cmp/str), using base+offset
addressing mode.
It also allows the builtin to be inlined for non-constant lengths.
No new regressions. Upgraded test case to handle former case.
OK for trunk ?
thanks
2014-01-09 Christian Bruel <christian.bruel@st.com>
* gcc/config/sh/sh-mem.cc (sh_expand_cmpnstr): Unroll small sizes and
optimized non constant lengths.
2014-01-09 Christian Bruel <christian.bruel@st.com>
* gcc.target/sh/cmpstrn.c: New case.
Index: gcc/config/sh/sh-mem.cc
===================================================================
--- gcc/config/sh/sh-mem.cc (revision 206385)
+++ gcc/config/sh/sh-mem.cc (working copy)
@@ -324,7 +324,6 @@ sh_expand_cmpnstr (rtx *operands)
rtx addr2 = operands[2];
rtx s1_addr = copy_addr_to_reg (XEXP (addr1, 0));
rtx s2_addr = copy_addr_to_reg (XEXP (addr2, 0));
- rtx tmp0 = gen_reg_rtx (SImode);
rtx tmp1 = gen_reg_rtx (SImode);
rtx tmp2 = gen_reg_rtx (SImode);
@@ -334,98 +333,128 @@ sh_expand_cmpnstr (rtx *operands)
rtx L_end_loop_byte = gen_label_rtx ();
rtx len = force_reg (SImode, operands[3]);
- int constp = (CONST_INT_P (operands[3]));
- int bytes = (constp ? INTVAL (operands[3]) : 0);
- int witers = bytes / 4;
+ int constp = CONST_INT_P (operands[3]);
- /* We could still loop on a register count. Not found very
- convincing to optimize yet. */
- if (! constp)
- return false;
+ /* Loop on a register count. */
+ if (constp)
+ {
+ rtx tmp0 = gen_reg_rtx (SImode);
+ rtx tmp3 = gen_reg_rtx (SImode);
+ rtx lenw = gen_reg_rtx (SImode);
- if (witers > 1)
- {
rtx L_loop_long = gen_label_rtx ();
rtx L_end_loop_long = gen_label_rtx ();
- rtx tmp3 = gen_reg_rtx (SImode);
- rtx lenw = gen_reg_rtx (SImode);
+ rtx L_small = gen_label_rtx ();
+
int align = INTVAL (operands[4]);
+ int bytes = INTVAL (operands[3]);
+ int witers = bytes / 4;
- emit_move_insn (tmp0, const0_rtx);
+ if (witers > 1)
+ {
+ addr1 = adjust_automodify_address (addr1, SImode, s1_addr, 0);
+ addr2 = adjust_automodify_address (addr2, SImode, s2_addr, 0);
- if (align < 4)
- {
- emit_insn (gen_iorsi3 (tmp1, s1_addr, s2_addr));
- emit_insn (gen_tstsi_t (GEN_INT (3), tmp1));
- jump = emit_jump_insn (gen_branch_false (L_loop_byte));
- add_int_reg_note (jump, REG_BR_PROB, prob_likely);
- }
+ emit_move_insn (tmp0, const0_rtx);
- addr1 = adjust_automodify_address (addr1, SImode, s1_addr, 0);
- addr2 = adjust_automodify_address (addr2, SImode, s2_addr, 0);
+ if (align < 4)
+ {
+ emit_insn (gen_iorsi3 (tmp1, s1_addr, s2_addr));
+ emit_insn (gen_tstsi_t (GEN_INT (3), tmp1));
+ jump = emit_jump_insn (gen_branch_false (L_loop_byte));
+ add_int_reg_note (jump, REG_BR_PROB, prob_likely);
+ }
- /* word count. Do we have iterations ? */
- emit_insn (gen_lshrsi3 (lenw, len, GEN_INT (2)));
+ /* word count. Do we have iterations ? */
+ emit_insn (gen_lshrsi3 (lenw, len, GEN_INT (2)));
- /*start long loop. */
- emit_label (L_loop_long);
+ /*start long loop. */
+ emit_label (L_loop_long);
- /* tmp2 is aligned, OK to load. */
- emit_move_insn (tmp2, addr2);
- emit_move_insn (s2_addr, plus_constant (Pmode, s2_addr, 4));
+ /* tmp2 is aligned, OK to load. */
+ emit_move_insn (tmp2, addr2);
+ emit_move_insn (s2_addr, plus_constant (Pmode, s2_addr, GET_MODE_SIZE (SImode)));
- /* tmp1 is aligned, OK to load. */
- emit_move_insn (tmp1, addr1);
- emit_move_insn (s1_addr, plus_constant (Pmode, s1_addr, 4));
+ /* tmp1 is aligned, OK to load. */
+ emit_move_insn (tmp1, addr1);
+ emit_move_insn (s1_addr, plus_constant (Pmode, s1_addr, GET_MODE_SIZE (SImode)));
- /* Is there a 0 byte ? */
- emit_insn (gen_andsi3 (tmp3, tmp2, tmp1));
+ /* Is there a 0 byte ? */
+ emit_insn (gen_andsi3 (tmp3, tmp2, tmp1));
- emit_insn (gen_cmpstr_t (tmp0, tmp3));
- jump = emit_jump_insn (gen_branch_true (L_end_loop_long));
- add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
+ emit_insn (gen_cmpstr_t (tmp0, tmp3));
+ jump = emit_jump_insn (gen_branch_true (L_end_loop_long));
+ add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
- emit_insn (gen_cmpeqsi_t (tmp1, tmp2));
- jump = emit_jump_insn (gen_branch_false (L_end_loop_long));
- add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
+ emit_insn (gen_cmpeqsi_t (tmp1, tmp2));
+ jump = emit_jump_insn (gen_branch_false (L_end_loop_long));
+ add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
- if (TARGET_SH2)
- emit_insn (gen_dect (lenw, lenw));
- else
- {
- emit_insn (gen_addsi3 (lenw, lenw, GEN_INT (-1)));
- emit_insn (gen_tstsi_t (lenw, lenw));
- }
- jump = emit_jump_insn (gen_branch_false (L_loop_long));
- add_int_reg_note (jump, REG_BR_PROB, prob_likely);
+ if (TARGET_SH2)
+ emit_insn (gen_dect (lenw, lenw));
+ else
+ {
+ emit_insn (gen_addsi3 (lenw, lenw, GEN_INT (-1)));
+ emit_insn (gen_tstsi_t (lenw, lenw));
+ }
- /* end loop. Reached max iterations. */
- if (bytes % 4 == 0)
- {
- /* Done. */
- jump = emit_jump_insn (gen_jump_compact (L_return));
- emit_barrier_after (jump);
- }
- else
- {
- /* Remaining bytes to read. */
- emit_move_insn (len, GEN_INT (bytes % 4));
- jump = emit_jump_insn (gen_jump_compact (L_loop_byte));
- emit_barrier_after (jump);
- }
+ jump = emit_jump_insn (gen_branch_false (L_loop_long));
+ add_int_reg_note (jump, REG_BR_PROB, prob_likely);
- emit_label (L_end_loop_long);
+ /* end loop. Reached max iterations. */
+ if (bytes % 4 == 0)
+ {
+ /* Done. */
+ jump = emit_jump_insn (gen_jump_compact (L_return));
+ emit_barrier_after (jump);
+ }
+ else
+ {
+ /* Remaining bytes to read. */
+ jump = emit_jump_insn (gen_jump_compact (L_small));
+ emit_barrier_after (jump);
+ }
- /* Remaining bytes to read. */
- emit_move_insn (len, GEN_INT (4));
+ emit_label (L_end_loop_long);
- /* Found last word. Restart it byte per byte. */
- emit_move_insn (s1_addr, plus_constant (Pmode, s1_addr, -4));
- emit_move_insn (s2_addr, plus_constant (Pmode, s2_addr, -4));
+ /* Found last word. Restart it byte per byte. */
+ bytes = 4;
+ emit_move_insn (s1_addr, plus_constant (Pmode, s1_addr, -GET_MODE_SIZE (SImode)));
+ emit_move_insn (s2_addr, plus_constant (Pmode, s2_addr, -GET_MODE_SIZE (SImode)));
+ }
+
+ emit_label (L_small);
+
+ gcc_assert (bytes <= 7);
+
+ addr1 = adjust_automodify_address (addr1, QImode, s1_addr, 0);
+ addr2 = adjust_automodify_address (addr2, QImode, s2_addr, 0);
+
+ while (bytes--)
+ {
+ emit_insn (gen_extendqisi2 (tmp1, addr1));
+ emit_insn (gen_extendqisi2 (tmp2, addr2));
+
+ emit_insn (gen_cmpeqsi_t (tmp2, const0_rtx));
+ jump = emit_jump_insn (gen_branch_true (L_end_loop_byte));
+ add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
+
+ emit_insn (gen_cmpeqsi_t (tmp1, tmp2));
+ if (flag_delayed_branch)
+ emit_insn (gen_zero_extendqisi2 (tmp2, gen_lowpart (QImode, tmp2)));
+ jump = emit_jump_insn (gen_branch_false (L_end_loop_byte));
+ add_int_reg_note (jump, REG_BR_PROB, prob_unlikely);
+
+ addr1 = adjust_address (addr1, QImode, GET_MODE_SIZE (QImode));
+ addr2 = adjust_address (addr2, QImode, GET_MODE_SIZE (QImode));
+ }
+
+ jump = emit_jump_insn (gen_jump_compact( L_end_loop_byte));
+ emit_barrier_after (jump);
}
- addr1 = adjust_address (addr1, QImode, 0);
- addr2 = adjust_address (addr2, QImode, 0);
+ addr1 = adjust_automodify_address (addr1, QImode, s1_addr, 0);
+ addr2 = adjust_automodify_address (addr2, QImode, s2_addr, 0);
emit_label (L_loop_byte);
Index: gcc/testsuite/gcc.target/sh/cmpstrn.c
===================================================================
--- gcc/testsuite/gcc.target/sh/cmpstrn.c (revision 206385)
+++ gcc/testsuite/gcc.target/sh/cmpstrn.c (working copy)
@@ -6,16 +6,23 @@
/* { dg-final { scan-assembler-not "jmp" } } */
/* { dg-final { scan-assembler-times "cmp/str" 1 } } */
-/* Test that the cmp/str loop is optimized out. */
-test01(const char *s1, const char *s2, int n)
+/* Test that cmp/str is not used for small lengths. */
+test01(const char *s1)
{
return __builtin_strncmp (s1, "abcde", 3);
}
/* Test that the cmp/str loop is used. */
-test02(const char *s1, const char *s2, int n)
+test02(const char *s1)
{
return __builtin_strncmp (s1, "abcdefghi", 8);
}
+/* Test that no call is generated */
+test03(const char *s1, int n)
+{
+ return __builtin_strncmp (s1, "abcde", n);
+}
+
+