commit d562629e36ba013b8f77956a74139330d191bc30 Author: Kyrylo Tkachov Date: Fri Jul 17 16:30:01 2015 +0100 [ARM][3/3] Expand mod by power of 2 diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index e1bc727..6ade07c 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -9556,6 +9556,22 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer_code, case MOD: case UMOD: + /* MOD by a power of 2 can be expanded as: + rsbs r1, r0, #0 + and r0, r0, #(n - 1) + and r1, r1, #(n - 1) + rsbpl r0, r1, #0. */ + if (code == MOD + && CONST_INT_P (XEXP (x, 1)) + && exact_log2 (INTVAL (XEXP (x, 1))) > 0 + && mode == SImode) + { + *cost += COSTS_N_INSNS (3) + + 2 * extra_cost->alu.logical + + extra_cost->alu.arith; + return true; + } + *cost = LIBCALL_COST (2); return false; /* All arguments must be in registers. */ diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md index f341109..8301648 100644 --- a/gcc/config/arm/arm.md +++ b/gcc/config/arm/arm.md @@ -1229,7 +1229,7 @@ (define_peephole2 "" ) -(define_insn "*subsi3_compare0" +(define_insn "subsi3_compare0" [(set (reg:CC_NOOV CC_REGNUM) (compare:CC_NOOV (minus:SI (match_operand:SI 1 "arm_rhs_operand" "r,r,I") @@ -2158,7 +2158,7 @@ (define_expand "andsi3" ) ; ??? Check split length for Thumb-2 -(define_insn_and_split "*arm_andsi3_insn" +(define_insn_and_split "arm_andsi3_insn" [(set (match_operand:SI 0 "s_register_operand" "=r,l,r,r,r") (and:SI (match_operand:SI 1 "s_register_operand" "%r,0,r,r,r") (match_operand:SI 2 "reg_or_int_operand" "I,l,K,r,?n")))] @@ -11105,6 +11105,78 @@ (define_expand "thumb_legacy_rev" "" ) +;; ARM-specific expansion of signed mod by power of 2 +;; using conditional negate. +;; For r0 % n where n is a power of 2 produce: +;; rsbs r1, r0, #0 +;; and r0, r0, #(n - 1) +;; and r1, r1, #(n - 1) +;; rsbpl r0, r1, #0 + +(define_expand "modsi3" + [(match_operand:SI 0 "register_operand" "") + (match_operand:SI 1 "register_operand" "") + (match_operand:SI 2 "const_int_operand" "")] + "TARGET_32BIT" + { + HOST_WIDE_INT val = INTVAL (operands[2]); + + if (val <= 0 + || exact_log2 (INTVAL (operands[2])) <= 0 + || !const_ok_for_arm (INTVAL (operands[2]) - 1)) + FAIL; + + rtx mask = GEN_INT (val - 1); + + /* In the special case of x0 % 2 we can do the even shorter: + cmp r0, #0 + and r0, r0, #1 + rsblt r0, r0, #0. */ + + if (val == 2) + { + rtx cc_reg = gen_rtx_REG (CCmode, CC_REGNUM); + rtx cond = gen_rtx_LT (SImode, cc_reg, const0_rtx); + + emit_insn (gen_rtx_SET (cc_reg, + gen_rtx_COMPARE (CCmode, operands[1], const0_rtx))); + + rtx masked = gen_reg_rtx (SImode); + emit_insn (gen_arm_andsi3_insn (masked, operands[1], mask)); + emit_move_insn (operands[0], + gen_rtx_IF_THEN_ELSE (SImode, cond, + gen_rtx_NEG (SImode, + masked), + masked)); + DONE; + } + + rtx neg_op = gen_reg_rtx (SImode); + rtx_insn *insn = emit_insn (gen_subsi3_compare0 (neg_op, const0_rtx, + operands[1])); + + /* Extract the condition register and mode. */ + rtx cmp = XVECEXP (PATTERN (insn), 0, 0); + rtx cc_reg = SET_DEST (cmp); + rtx cond = gen_rtx_GE (SImode, cc_reg, const0_rtx); + + emit_insn (gen_arm_andsi3_insn (operands[0], operands[1], mask)); + + rtx masked_neg = gen_reg_rtx (SImode); + emit_insn (gen_arm_andsi3_insn (masked_neg, neg_op, mask)); + + /* We want a conditional negate here, but emitting COND_EXEC rtxes + during expand does not always work. Do an IF_THEN_ELSE instead. */ + emit_move_insn (operands[0], + gen_rtx_IF_THEN_ELSE (SImode, cond, + gen_rtx_NEG (SImode, masked_neg), + operands[0])); + + + DONE; + } +) + (define_expand "bswapsi2" [(set (match_operand:SI 0 "s_register_operand" "=r") (bswap:SI (match_operand:SI 1 "s_register_operand" "r")))] diff --git a/gcc/testsuite/gcc.target/aarch64/mod_2.c b/gcc/testsuite/gcc.target/aarch64/mod_2.c new file mode 100644 index 0000000..2645c18 --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/mod_2.c @@ -0,0 +1,7 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mcpu=cortex-a57 -save-temps" } */ + +#include "mod_2.x" + +/* { dg-final { scan-assembler "csneg\t\[wx\]\[0-9\]*" } } */ +/* { dg-final { scan-assembler-times "and\t\[wx\]\[0-9\]*" 1 } } */ diff --git a/gcc/testsuite/gcc.target/aarch64/mod_2.x b/gcc/testsuite/gcc.target/aarch64/mod_2.x new file mode 100644 index 0000000..2b079a4 --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/mod_2.x @@ -0,0 +1,5 @@ +int +f (int x) +{ + return x % 2; +} diff --git a/gcc/testsuite/gcc.target/aarch64/mod_256.c b/gcc/testsuite/gcc.target/aarch64/mod_256.c new file mode 100644 index 0000000..567332c --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/mod_256.c @@ -0,0 +1,6 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mcpu=cortex-a57 -save-temps" } */ + +#include "mod_256.x" + +/* { dg-final { scan-assembler "csneg\t\[wx\]\[0-9\]*" } } */ diff --git a/gcc/testsuite/gcc.target/aarch64/mod_256.x b/gcc/testsuite/gcc.target/aarch64/mod_256.x new file mode 100644 index 0000000..c1de42c --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/mod_256.x @@ -0,0 +1,5 @@ +int +f (int x) +{ + return x % 256; +} diff --git a/gcc/testsuite/gcc.target/arm/mod_2.c b/gcc/testsuite/gcc.target/arm/mod_2.c new file mode 100644 index 0000000..93017a1 --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/mod_2.c @@ -0,0 +1,8 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target arm32 } */ +/* { dg-options "-O2 -mcpu=cortex-a57 -save-temps" } */ + +#include "../aarch64/mod_2.x" + +/* { dg-final { scan-assembler "rsblt\tr\[0-9\]*" } } */ +/* { dg-final { scan-assembler-times "and\tr\[0-9\].*1" 1 } } */ diff --git a/gcc/testsuite/gcc.target/arm/mod_256.c b/gcc/testsuite/gcc.target/arm/mod_256.c new file mode 100644 index 0000000..92ab05a --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/mod_256.c @@ -0,0 +1,8 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target arm32 } */ +/* { dg-options "-O2 -mcpu=cortex-a57 -save-temps" } */ + +#include "../aarch64/mod_256.x" + +/* { dg-final { scan-assembler "rsbpl\tr\[0-9\]*" } } */ +/* { dg-final { scan-assembler "and\tr\[0-9\].*255" } } */