From patchwork Mon May 9 16:23:06 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Stubbs X-Patchwork-Id: 1425 Return-Path: Delivered-To: unknown Received: from imap.gmail.com (74.125.159.109) by localhost6.localdomain6 with IMAP4-SSL; 08 Jun 2011 14:51:52 -0000 Delivered-To: patches@linaro.org Received: by 10.224.184.145 with SMTP id ck17cs62696qab; Mon, 9 May 2011 09:23:13 -0700 (PDT) Received: by 10.42.26.83 with SMTP id e19mr2306532icc.387.1304958193151; Mon, 09 May 2011 09:23:13 -0700 (PDT) Received: from mail.codesourcery.com (mail.codesourcery.com [38.113.113.100]) by mx.google.com with ESMTPS id ht5si17235183icb.104.2011.05.09.09.23.11 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 09 May 2011 09:23:12 -0700 (PDT) Received-SPF: pass (google.com: domain of ams@codesourcery.com designates 38.113.113.100 as permitted sender) client-ip=38.113.113.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ams@codesourcery.com designates 38.113.113.100 as permitted sender) smtp.mail=ams@codesourcery.com Received: (qmail 16315 invoked from network); 9 May 2011 16:23:09 -0000 Received: from unknown (HELO ?10.155.4.80?) (ams@127.0.0.2) by mail.codesourcery.com with ESMTPA; 9 May 2011 16:23:09 -0000 Message-ID: <4DC814EA.4070608@codesourcery.com> Date: Mon, 09 May 2011 18:23:06 +0200 From: Andrew Stubbs Organization: CodeSourcery User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Richard Earnshaw CC: gcc-patches@gcc.gnu.org, patches@linaro.org Subject: Re: [PATCH][ARM] Thumb2 replicated constants References: <4DB013B7.4090504@codesourcery.com> <1304677098.5165.7.camel@e102346-lin.cambridge.arm.com> In-Reply-To: <1304677098.5165.7.camel@e102346-lin.cambridge.arm.com> On 06/05/11 12:18, Richard Earnshaw wrote: > + RETURN_SEQUENCE must be an int[4]. > > It would be a more robust coding style to define a struct with an int[4] > array as its only member. Then it wouldn't be possible to pass an > undersized object to these routines. I've attached an updated patch with this change. > OK with a change to do that. Thanks, I can't commit this until my ADDW/SUBW patch has been committed. Andrew 2011-05-09 Andrew Stubbs gcc/ * config/arm/arm.c (struct four_ints): New type. (count_insns_for_constant): Delete function. (find_best_start): Delete function. (optimal_immediate_sequence): New function. (optimal_immediate_sequence_1): New function. (arm_gen_constant): Move constant splitting code to optimal_immediate_sequence. Rewrite constant negation/invertion code. gcc/testsuite/ * gcc.target/arm/thumb2-replicated-constant1.c: New file. * gcc.target/arm/thumb2-replicated-constant2.c: New file. * gcc.target/arm/thumb2-replicated-constant3.c: New file. * gcc.target/arm/thumb2-replicated-constant4.c: New file. --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -64,6 +64,11 @@ typedef struct minipool_fixup Mfix; void (*arm_lang_output_object_attributes_hook)(void); +struct four_ints +{ + int i[4]; +}; + /* Forward function declarations. */ static bool arm_needs_doubleword_align (enum machine_mode, const_tree); static int arm_compute_static_chain_stack_bytes (void); @@ -129,7 +134,13 @@ static void thumb1_output_function_prologue (FILE *, HOST_WIDE_INT); static int arm_comp_type_attributes (const_tree, const_tree); static void arm_set_default_type_attributes (tree); static int arm_adjust_cost (rtx, rtx, rtx, int); -static int count_insns_for_constant (HOST_WIDE_INT, int); +static int optimal_immediate_sequence (enum rtx_code code, + unsigned HOST_WIDE_INT val, + struct four_ints *return_sequence); +static int optimal_immediate_sequence_1 (enum rtx_code code, + unsigned HOST_WIDE_INT val, + struct four_ints *return_sequence, + int i); static int arm_get_strip_length (int); static bool arm_function_ok_for_sibcall (tree, tree); static enum machine_mode arm_promote_function_mode (const_tree, @@ -2441,68 +2452,41 @@ arm_split_constant (enum rtx_code code, enum machine_mode mode, rtx insn, 1); } -/* Return the number of instructions required to synthesize the given - constant, if we start emitting them from bit-position I. */ -static int -count_insns_for_constant (HOST_WIDE_INT remainder, int i) -{ - HOST_WIDE_INT temp1; - int step_size = TARGET_ARM ? 2 : 1; - int num_insns = 0; - - gcc_assert (TARGET_ARM || i == 0); - - do - { - int end; - - if (i <= 0) - i += 32; - if (remainder & (((1 << step_size) - 1) << (i - step_size))) - { - end = i - 8; - if (end < 0) - end += 32; - temp1 = remainder & ((0x0ff << end) - | ((i < end) ? (0xff >> (32 - end)) : 0)); - remainder &= ~temp1; - num_insns++; - i -= 8 - step_size; - } - i -= step_size; - } while (remainder); - return num_insns; -} - +/* Return a sequence of integers, in RETURN_SEQUENCE that fit into + ARM/THUMB2 immediates, and add up to VAL. + Thr function return value gives the number of insns required. */ static int -find_best_start (unsigned HOST_WIDE_INT remainder) +optimal_immediate_sequence (enum rtx_code code, unsigned HOST_WIDE_INT val, + struct four_ints *return_sequence) { int best_consecutive_zeros = 0; int i; int best_start = 0; + int insns1, insns2; + struct four_ints tmp_sequence; /* If we aren't targetting ARM, the best place to start is always at - the bottom. */ - if (! TARGET_ARM) - return 0; - - for (i = 0; i < 32; i += 2) + the bottom, otherwise look more closely. */ + if (TARGET_ARM) { - int consecutive_zeros = 0; - - if (!(remainder & (3 << i))) + for (i = 0; i < 32; i += 2) { - while ((i < 32) && !(remainder & (3 << i))) - { - consecutive_zeros += 2; - i += 2; - } - if (consecutive_zeros > best_consecutive_zeros) + int consecutive_zeros = 0; + + if (!(val & (3 << i))) { - best_consecutive_zeros = consecutive_zeros; - best_start = i - consecutive_zeros; + while ((i < 32) && !(val & (3 << i))) + { + consecutive_zeros += 2; + i += 2; + } + if (consecutive_zeros > best_consecutive_zeros) + { + best_consecutive_zeros = consecutive_zeros; + best_start = i - consecutive_zeros; + } + i -= 2; } - i -= 2; } } @@ -2529,13 +2513,161 @@ find_best_start (unsigned HOST_WIDE_INT remainder) the constant starting from `best_start', and also starting from zero (i.e. with bit 31 first to be output). If `best_start' doesn't yield a shorter sequence, we may as well use zero. */ + insns1 = optimal_immediate_sequence_1 (code, val, return_sequence, best_start); if (best_start != 0 - && ((((unsigned HOST_WIDE_INT) 1) << best_start) < remainder) - && (count_insns_for_constant (remainder, 0) <= - count_insns_for_constant (remainder, best_start))) - best_start = 0; + && ((((unsigned HOST_WIDE_INT) 1) << best_start) < val)) + { + insns2 = optimal_immediate_sequence_1 (code, val, &tmp_sequence, 0); + if (insns2 <= insns1) + { + *return_sequence = tmp_sequence; + insns1 = insns2; + } + } + + return insns1; +} + +/* As for optimal_immediate_sequence, but starting at bit-position I. */ +static int +optimal_immediate_sequence_1 (enum rtx_code code, unsigned HOST_WIDE_INT val, + struct four_ints *return_sequence, int i) +{ + int remainder = val & 0xffffffff; + int insns = 0; + + /* Try and find a way of doing the job in either two or three + instructions. + + In ARM mode we can use 8-bit constants, rotated to any 2-bit aligned + location. We start at position I. This may be the MSB, or + optimial_immediate_sequence may have positioned it at the largest block + of zeros that are aligned on a 2-bit boundary. We then fill up the temps, + wrapping around to the top of the word when we drop off the bottom. + In the worst case this code should produce no more than four insns. + + In Thumb2 mode, we can use 32/16-bit replicated constants, and 8-bit + constants, shifted to any arbitrary location. We should always start + at the MSB. */ + do + { + int end; + int b1, b2, b3, b4; + unsigned HOST_WIDE_INT result; + int loc; + + gcc_assert (insns < 4); + + if (i <= 0) + i += 32; + + /* First, find the next normal 12/8-bit shifted/rotated immediate. */ + if (remainder & ((TARGET_ARM ? (3 << (i - 2)) : (1 << (i - 1))))) + { + loc = i; + if (i <= 12 && TARGET_THUMB2 && code == PLUS) + /* We can use addw/subw for the last 12 bits. */ + result = remainder; + else + { + /* Use an 8-bit shifted/rotated immediate. */ + end = i - 8; + if (end < 0) + end += 32; + result = remainder & ((0x0ff << end) + | ((i < end) ? (0xff >> (32 - end)) + : 0)); + i -= 8; + } + } + else + { + /* Arm allows rotates by a multiple of two. Thumb-2 allows + arbitrary shifts. */ + i -= TARGET_ARM ? 2 : 1; + continue; + } + + /* Next, see if we can do a better job with a thumb2 replicated + constant. + + We do it this way around to catch the cases like 0x01F001E0 where + two 8-bit immediates would work, but a replicated constant would + make it worse. + + TODO: 16-bit constants that don't clear all the bits, but still win. + TODO: Arithmetic splitting for set/add/sub, rather than bitwise. */ + if (TARGET_THUMB2) + { + b1 = (remainder & 0xff000000) >> 24; + b2 = (remainder & 0x00ff0000) >> 16; + b3 = (remainder & 0x0000ff00) >> 8; + b4 = remainder & 0xff; - return best_start; + if (loc > 24) + { + /* The 8-bit immediate already found clears b1 (and maybe b2), + but must leave b3 and b4 alone. */ + + /* First try to find a 32-bit replicated constant that clears + almost everything. We can assume that we can't do it in one, + or else we wouldn't be here. */ + unsigned int tmp = b1 & b2 & b3 & b4; + unsigned int tmp2 = tmp + (tmp << 8) + (tmp << 16) + + (tmp << 24); + unsigned int matching_bytes = (tmp == b1) + (tmp == b2) + + (tmp == b3) + (tmp == b4); + if (tmp + && (matching_bytes >= 3 + || (matching_bytes == 2 + && const_ok_for_op (remainder & ~tmp2, code)))) + { + /* At least 3 of the bytes match, and the fourth has at + least as many bits set, or two of the bytes match + and it will only require one more insn to finish. */ + result = tmp2; + i = tmp != b1 ? 32 + : tmp != b2 ? 24 + : tmp != b3 ? 16 + : 8; + } + + /* Second, try to find a 16-bit replicated constant that can + leave three of the bytes clear. If b2 or b4 is already + zero, then we can. If the 8-bit from above would not + clear b2 anyway, then we still win. */ + else if (b1 == b3 && (!b2 || !b4 + || (remainder & 0x00ff0000 & ~result))) + { + result = remainder & 0xff00ff00; + i = 24; + } + } + else if (loc > 16) + { + /* The 8-bit immediate already found clears b2 (and maybe b3) + and we don't get here unless b1 is alredy clear, but it will + leave b4 unchanged. */ + + /* If we can clear b2 and b4 at once, then we win, since the + 8-bits couldn't possibly reach that far. */ + if (b2 == b4) + { + result = remainder & 0x00ff00ff; + i = 16; + } + } + } + + return_sequence->i[insns++] = result; + remainder &= ~result; + + if (code == SET || code == MINUS) + code = PLUS; + } + while (remainder); + + return insns; } /* Emit an instruction with the indicated PATTERN. If COND is @@ -2552,7 +2684,6 @@ emit_constant_insn (rtx cond, rtx pattern) /* As above, but extra parameter GENERATE which, if clear, suppresses RTL generation. */ -/* ??? This needs more work for thumb2. */ static int arm_gen_constant (enum rtx_code code, enum machine_mode mode, rtx cond, @@ -2563,15 +2694,15 @@ arm_gen_constant (enum rtx_code code, enum machine_mode mode, rtx cond, int can_negate = 0; int final_invert = 0; int i; - int num_bits_set = 0; int set_sign_bit_copies = 0; int clear_sign_bit_copies = 0; int clear_zero_bit_copies = 0; int set_zero_bit_copies = 0; - int insns = 0; + int insns = 0, neg_insns, inv_insns; unsigned HOST_WIDE_INT temp1, temp2; unsigned HOST_WIDE_INT remainder = val & 0xffffffff; - int step_size = TARGET_ARM ? 2 : 1; + struct four_ints *immediates; + struct four_ints pos_immediates, neg_immediates, inv_immediates; /* Find out which operations are safe for a given CODE. Also do a quick check for degenerate cases; these can occur when DImode operations @@ -3082,120 +3213,102 @@ arm_gen_constant (enum rtx_code code, enum machine_mode mode, rtx cond, break; } - for (i = 0; i < 32; i++) - if (remainder & (1 << i)) - num_bits_set++; + /* Calculate what the instruction sequences would be if we generated it + normally, negated, or inverted. */ + if (code == AND) + /* AND cannot be split into multiple insns, so invert and use BIC. */ + insns = 99; + else + insns = optimal_immediate_sequence (code, remainder, &pos_immediates); + + if (can_negate) + neg_insns = optimal_immediate_sequence (code, (-remainder) & 0xffffffff, + &neg_immediates); + else + neg_insns = 99; + + if (can_invert) + inv_insns = optimal_immediate_sequence (code, remainder ^ 0xffffffff, + &inv_immediates); + else + inv_insns = 99; - if ((code == AND) || (can_invert && num_bits_set > 16)) - remainder ^= 0xffffffff; - else if (code == PLUS && num_bits_set > 16) - remainder = (-remainder) & 0xffffffff; + immediates = &pos_immediates; - /* For XOR, if more than half the bits are set and there's a sequence - of more than 8 consecutive ones in the pattern then we can XOR by the - inverted constant and then invert the final result; this may save an - instruction and might also lead to the final mvn being merged with - some other operation. */ - else if (code == XOR && num_bits_set > 16 - && (count_insns_for_constant (remainder ^ 0xffffffff, - find_best_start - (remainder ^ 0xffffffff)) - < count_insns_for_constant (remainder, - find_best_start (remainder)))) + /* Is the negated immediate sequence more efficient? */ + if (neg_insns < insns && neg_insns <= inv_insns) { - remainder ^= 0xffffffff; - final_invert = 1; + insns = neg_insns; + immediates = &neg_immediates; } else + can_negate = 0; + + /* Is the inverted immediate sequence more efficient? + We must allow for an extra NOT instruction for XOR operations, although + there is some chance that the final 'mvn' will get optimized later. */ + if (inv_insns < insns && (code != XOR || (inv_insns + 1) < insns)) { - can_invert = 0; - can_negate = 0; - } + insns = inv_insns; + immediates = &inv_immediates; - /* Now try and find a way of doing the job in either two or three - instructions. - We start by looking for the largest block of zeros that are aligned on - a 2-bit boundary, we then fill up the temps, wrapping around to the - top of the word when we drop off the bottom. - In the worst case this code should produce no more than four insns. - Thumb-2 constants are shifted, not rotated, so the MSB is always the - best place to start. */ + if (code == XOR) + final_invert = 1; + } + else + can_invert = 0; - /* ??? Use thumb2 replicated constants when the high and low halfwords are - the same. */ - { - /* Now start emitting the insns. */ - i = find_best_start (remainder); - do - { - int end; + /* Now output the chosen sequence as instructions. */ + if (generate) + { + for (i = 0; i < insns; i++) + { + rtx new_src, temp1_rtx; - if (i <= 0) - i += 32; - if (remainder & (3 << (i - 2))) - { - end = i - 8; - if (end < 0) - end += 32; - temp1 = remainder & ((0x0ff << end) - | ((i < end) ? (0xff >> (32 - end)) : 0)); - remainder &= ~temp1; - - if (generate) - { - rtx new_src, temp1_rtx; + temp1 = immediates->i[i]; - if (code == SET || code == MINUS) - { - new_src = (subtargets ? gen_reg_rtx (mode) : target); - if (can_invert && code != MINUS) - temp1 = ~temp1; - } - else - { - if ((final_invert || remainder) && subtargets) - new_src = gen_reg_rtx (mode); - else - new_src = target; - if (can_invert) - temp1 = ~temp1; - else if (can_negate) - temp1 = -temp1; - } + if (code == SET || code == MINUS) + { + new_src = (subtargets ? gen_reg_rtx (mode) : target); + if (can_invert && code != MINUS) + temp1 = ~temp1; + } + else + { + if ((final_invert || i < (insns - 1)) && subtargets) + new_src = gen_reg_rtx (mode); + else + new_src = target; + if (can_invert) + temp1 = ~temp1; + else if (can_negate) + temp1 = -temp1; + } - temp1 = trunc_int_for_mode (temp1, mode); - temp1_rtx = GEN_INT (temp1); + temp1 = trunc_int_for_mode (temp1, mode); + temp1_rtx = GEN_INT (temp1); - if (code == SET) - ; - else if (code == MINUS) - temp1_rtx = gen_rtx_MINUS (mode, temp1_rtx, source); - else - temp1_rtx = gen_rtx_fmt_ee (code, mode, source, temp1_rtx); + if (code == SET) + ; + else if (code == MINUS) + temp1_rtx = gen_rtx_MINUS (mode, temp1_rtx, source); + else + temp1_rtx = gen_rtx_fmt_ee (code, mode, source, temp1_rtx); - emit_constant_insn (cond, - gen_rtx_SET (VOIDmode, new_src, - temp1_rtx)); - source = new_src; - } + emit_constant_insn (cond, + gen_rtx_SET (VOIDmode, new_src, + temp1_rtx)); + source = new_src; - if (code == SET) - { - can_invert = 0; - code = PLUS; - } - else if (code == MINUS) + if (code == SET) + { + can_invert = 0; code = PLUS; - - insns++; - i -= 8 - step_size; - } - /* Arm allows rotates by a multiple of two. Thumb-2 allows arbitrary - shifts. */ - i -= step_size; - } - while (remainder); - } + } + else if (code == MINUS) + code = PLUS; + } + } if (final_invert) { --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/thumb2-replicated-constant1.c @@ -0,0 +1,27 @@ +/* Ensure simple replicated constant immediates work. */ +/* { dg-options "-mthumb -O2" } */ +/* { dg-require-effective-target arm_thumb2_ok } */ + +int +foo1 (int a) +{ + return a + 0xfefefefe; +} + +/* { dg-final { scan-assembler "add.*#-16843010" } } */ + +int +foo2 (int a) +{ + return a - 0xab00ab00; +} + +/* { dg-final { scan-assembler "sub.*#-1426019584" } } */ + +int +foo3 (int a) +{ + return a & 0x00cd00cd; +} + +/* { dg-final { scan-assembler "and.*#13435085" } } */ --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/thumb2-replicated-constant2.c @@ -0,0 +1,75 @@ +/* Ensure split constants can use replicated patterns. */ +/* { dg-options "-mthumb -O2" } */ +/* { dg-require-effective-target arm_thumb2_ok } */ + +int +foo1 (int a) +{ + return a + 0xfe00fe01; +} + +/* { dg-final { scan-assembler "add.*#-33489408" } } */ +/* { dg-final { scan-assembler "add.*#1" } } */ + +int +foo2 (int a) +{ + return a + 0xdd01dd00; +} + +/* { dg-final { scan-assembler "add.*#-587145984" } } */ +/* { dg-final { scan-assembler "add.*#65536" } } */ + +int +foo3 (int a) +{ + return a + 0x00443344; +} + +/* { dg-final { scan-assembler "add.*#4456516" } } */ +/* { dg-final { scan-assembler "add.*#13056" } } */ + +int +foo4 (int a) +{ + return a + 0x77330033; +} + +/* { dg-final { scan-assembler "add.*#1996488704" } } */ +/* { dg-final { scan-assembler "add.*#3342387" } } */ + +int +foo5 (int a) +{ + return a + 0x11221122; +} + +/* { dg-final { scan-assembler "add.*#285217024" } } */ +/* { dg-final { scan-assembler "add.*#2228258" } } */ + +int +foo6 (int a) +{ + return a + 0x66666677; +} + +/* { dg-final { scan-assembler "add.*#1717986918" } } */ +/* { dg-final { scan-assembler "add.*#17" } } */ + +int +foo7 (int a) +{ + return a + 0x99888888; +} + +/* { dg-final { scan-assembler "add.*#-2004318072" } } */ +/* { dg-final { scan-assembler "add.*#285212672" } } */ + +int +foo8 (int a) +{ + return a + 0xdddddfff; +} + +/* { dg-final { scan-assembler "add.*#-572662307" } } */ +/* { dg-final { scan-assembler "addw.*#546" } } */ --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/thumb2-replicated-constant3.c @@ -0,0 +1,28 @@ +/* Ensure negated/inverted replicated constant immediates work. */ +/* { dg-options "-mthumb -O2" } */ +/* { dg-require-effective-target arm_thumb2_ok } */ + +int +foo1 (int a) +{ + return a | 0xffffff00; +} + +/* { dg-final { scan-assembler "orn.*#255" } } */ + +int +foo2 (int a) +{ + return a & 0xffeeffee; +} + +/* { dg-final { scan-assembler "bic.*#1114129" } } */ + +int +foo3 (int a) +{ + return a & 0xaaaaaa00; +} + +/* { dg-final { scan-assembler "and.*#-1431655766" } } */ +/* { dg-final { scan-assembler "bic.*#170" } } */ --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/thumb2-replicated-constant4.c @@ -0,0 +1,22 @@ +/* Ensure replicated constants don't make things worse. */ +/* { dg-options "-mthumb -O2" } */ +/* { dg-require-effective-target arm_thumb2_ok } */ + +int +foo1 (int a) +{ + /* It might be tempting to use 0x01000100, but it wouldn't help. */ + return a + 0x01f001e0; +} + +/* { dg-final { scan-assembler "add.*#32505856" } } */ +/* { dg-final { scan-assembler "add.*#480" } } */ + +int +foo2 (int a) +{ + return a + 0x0f100e10; +} + +/* { dg-final { scan-assembler "add.*#252706816" } } */ +/* { dg-final { scan-assembler "add.*#3600" } } */