On Mon, May 9, 2022 at 7:19 AM liuhongt <hongtao....@intel.com> wrote:
>
> This patch will enable below optimization:
>
> {
> - int bit;
> - long long unsigned int _1;
> - long long unsigned int _2;
> -
> <bb 2> [local count: 46707768]:
> -
> - <bb 3> [local count: 1027034057]:
> - # tmp_11 = PHI <tmp_8(3), tmp_6(D)(2)>
> - # bit_13 = PHI <bit_9(3), 63(2)>
> - _1 = 1 << bit_13;
> - _2 = ~_1;
> - tmp_8 = _2 & tmp_11;
> - bit_9 = bit_13 + -3;
> - if (bit_9 != -3(OVF))
> - goto <bb 3>; [95.65%]
> - else
> - goto <bb 4>; [4.35%]
> -
> - <bb 4> [local count: 46707768]:
> - return tmp_8;
> + tmp_12 = tmp_6(D) & 7905747460161236406;
> + return tmp_12;
>
> }
>
>
> Boostrapped and regtested on x86_64-pc-linux-gnu{-m32,}
> Ok for trunk?
>
> gcc/ChangeLog:
>
> PR middle-end/103462
> * match.pd (bitwise_induction_p): New match.
> * tree-scalar-evolution.c (gimple_bitwise_induction_p):
> Declare.
> (analyze_and_compute_bitwise_induction_effect): New function.
> (enum bit_op_kind): New enum.
> (final_value_replacement_loop): Enhanced to handle bitwise
> induction.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr103462-1.c: New test.
> * gcc.target/i386/pr103462-2.c: New test.
> * gcc.target/i386/pr103462-3.c: New test.
> * gcc.target/i386/pr103462-4.c: New test.
> * gcc.target/i386/pr103462-5.c: New test.
> * gcc.target/i386/pr103462-6.c: New test.
> ---
> gcc/match.pd | 7 +
> gcc/testsuite/gcc.target/i386/pr103462-1.c | 111 +++++++++++++
> gcc/testsuite/gcc.target/i386/pr103462-2.c | 45 ++++++
> gcc/testsuite/gcc.target/i386/pr103462-3.c | 111 +++++++++++++
> gcc/testsuite/gcc.target/i386/pr103462-4.c | 46 ++++++
> gcc/testsuite/gcc.target/i386/pr103462-5.c | 111 +++++++++++++
> gcc/testsuite/gcc.target/i386/pr103462-6.c | 46 ++++++
> gcc/tree-scalar-evolution.cc | 178 ++++++++++++++++++++-
> 8 files changed, 654 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-1.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-2.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-3.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-4.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-5.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103462-6.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 6d691d302b3..24ff5f9e6a8 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -7746,3 +7746,10 @@ and,
> == TYPE_UNSIGNED (TREE_TYPE (@3))))
> && single_use (@4)
> && single_use (@5))))
> +
> +(for bit_op (bit_and bit_ior bit_xor)
> + (match (bitwise_induction_p @0 @2 @3)
> + (bit_op:c (nop_convert1? (bit_not2?@0 (convert3? (lshift integer_onep@1
> @2)))) @3)))
> +
> +(match (bitwise_induction_p @0 @2 @3)
> + (bit_not (nop_convert1? (bit_xor@0 (convert2? (lshift integer_onep@1 @2))
> @3))))
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-1.c
> b/gcc/testsuite/gcc.target/i386/pr103462-1.c
> new file mode 100644
> index 00000000000..1dc4c2acad6
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-1.c
> @@ -0,0 +1,111 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-sccp-details" } */
> +/* { dg-final { scan-tree-dump-times {final value replacement} 12 "sccp" } }
> */
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp &= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo1 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp &= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo2 (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp &= (1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo3 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp &= (1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo4 (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp |= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo5 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp |= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo6 (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp |= (1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo7 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp |= (1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo8 (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp ^= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo9 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp ^= ~(1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo10 (unsigned long long tmp)
> +{
> + for (int bit = 0; bit < 64; bit += 3)
> + tmp ^= (1ULL << bit);
> + return tmp;
> +}
> +
> +unsigned long long
> +__attribute__((noipa))
> +foo11 (unsigned long long tmp)
> +{
> + for (int bit = 63; bit >= 0; bit -= 3)
> + tmp ^= (1ULL << bit);
> + return tmp;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-2.c
> b/gcc/testsuite/gcc.target/i386/pr103462-2.c
> new file mode 100644
> index 00000000000..bc375cb78d4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-2.c
> @@ -0,0 +1,45 @@
> +/* { dg-do run } */
> +/* { dg-options "-O1" } */
> +
> +#include "pr103462-1.c"
> +
> +int main()
> +{
> + unsigned long long tmp = 0x1111111111111111ULL;
> + if (foo (tmp) != 0x110110110110110ULL)
> + __builtin_abort ();
> +
> + if (foo1 (tmp) != 0x110110110110110ULL)
> + __builtin_abort ();
> +
> + if (foo2 (tmp) != 0x0ULL)
> + __builtin_abort ();
> +
> + if (foo3 (tmp) != 0x0ULL)
> + __builtin_abort ();
> +
> + if (foo4 (tmp) != 0xffffffffffffffffULL)
> + __builtin_abort ();
> +
> + if (foo5 (tmp) != 0xffffffffffffffffULL)
> + __builtin_abort ();
> +
> + if (foo6 (tmp) != 0x9359359359359359ULL)
> + __builtin_abort ();
> +
> + if (foo7 (tmp) != 0x9359359359359359ULL)
> + __builtin_abort ();
> +
> + if (foo8 (tmp) != 0x8358358358358358ULL)
> + __builtin_abort ();
> +
> + if (foo9 (tmp) != 0x8358358358358358ULL)
> + __builtin_abort ();
> +
> + if (foo10 (tmp) != 0x8358358358358358ULL)
> + __builtin_abort ();
> +
> + if (foo11 (tmp) != 0x8358358358358358ULL)
> + __builtin_abort ();
> +}
> +
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-3.c
> b/gcc/testsuite/gcc.target/i386/pr103462-3.c
> new file mode 100644
> index 00000000000..4ba248a4872
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-3.c
> @@ -0,0 +1,111 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-sccp-details" } */
> +/* { dg-final { scan-tree-dump-times {final value replacement} 12 "sccp" } }
> */
> +
> +unsigned int
> +__attribute__((noipa))
> +foo (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp &= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo1 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp &= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo2 (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp &= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo3 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp &= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo4 (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp |= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo5 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp |= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo6 (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp |= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo7 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp |= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo8 (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp ^= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo9 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp ^= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo10 (unsigned int tmp)
> +{
> + for (int bit = 0; bit < 32; bit += 3)
> + tmp ^= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned int
> +__attribute__((noipa))
> +foo11 (unsigned int tmp)
> +{
> + for (int bit = 31; bit >= 0; bit -= 3)
> + tmp ^= (1U << bit);
> + return tmp;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-4.c
> b/gcc/testsuite/gcc.target/i386/pr103462-4.c
> new file mode 100644
> index 00000000000..e2f4056f525
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-4.c
> @@ -0,0 +1,46 @@
> +/* { dg-do run } */
> +/* { dg-options "-O1" } */
> +
> +#include "pr103462-3.c"
> +
> +int main()
> +{
> + unsigned int tmp = 0x11111111U;
> +
> + if (foo (tmp) != 0x10110110U)
> + __builtin_abort ();
> +
> + if (foo1 (tmp) != 0x1101101U)
> + __builtin_abort ();
> +
> + if (foo2 (tmp) != 0x0U)
> + __builtin_abort ();
> +
> + if (foo3 (tmp) != 0x0U)
> + __builtin_abort ();
> +
> + if (foo4 (tmp) != 0xffffffffU)
> + __builtin_abort ();
> +
> + if (foo5 (tmp) != 0xffffffffU)
> + __builtin_abort ();
> +
> + if (foo6 (tmp) != 0x59359359U)
> + __builtin_abort ();
> +
> + if (foo7 (tmp) != 0x93593593U)
> + __builtin_abort ();
> +
> + if (foo8 (tmp) != 0xa7ca7ca7U)
> + __builtin_abort ();
> +
> + if (foo9 (tmp) != 0x7ca7ca7cU)
> + __builtin_abort ();
> +
> + if (foo10 (tmp) != 0x58358358U)
> + __builtin_abort ();
> +
> + if (foo11 (tmp) != 0x83583583U)
> + __builtin_abort ();
> +}
> +
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-5.c
> b/gcc/testsuite/gcc.target/i386/pr103462-5.c
> new file mode 100644
> index 00000000000..1f4ffa34b48
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-5.c
> @@ -0,0 +1,111 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-sccp-details" } */
> +/* { dg-final { scan-tree-dump-times {final value replacement} 12 "sccp" } }
> */
> +
> +unsigned short
> +__attribute__((noipa))
> +foo (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp &= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo1 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp &= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo2 (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp &= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo3 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp &= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo4 (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp |= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo5 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp |= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo6 (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp |= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo7 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp |= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo8 (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp ^= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo9 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp ^= ~(1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo10 (unsigned short tmp)
> +{
> + for (int bit = 0; bit < 16; bit += 3)
> + tmp ^= (1U << bit);
> + return tmp;
> +}
> +
> +unsigned short
> +__attribute__((noipa))
> +foo11 (unsigned short tmp)
> +{
> + for (int bit = 15; bit >= 0; bit -= 3)
> + tmp ^= (1U << bit);
> + return tmp;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103462-6.c
> b/gcc/testsuite/gcc.target/i386/pr103462-6.c
> new file mode 100644
> index 00000000000..65426d71efe
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103462-6.c
> @@ -0,0 +1,46 @@
> +/* { dg-do run } */
> +/* { dg-options "-O1" } */
> +
> +#include "pr103462-5.c"
> +
> +int main()
> +{
> + unsigned short tmp = 0x1111U;
> +
> + if (foo (tmp) != 0x110)
> + __builtin_abort ();
> +
> + if (foo1 (tmp) != 0x110)
> + __builtin_abort ();
> +
> + if (foo2 (tmp) != 0x0)
> + __builtin_abort ();
> +
> + if (foo3 (tmp) != 0x0)
> + __builtin_abort ();
> +
> + if (foo4 (tmp) != 0xffff)
> + __builtin_abort ();
> +
> + if (foo5 (tmp) != 0xffff)
> + __builtin_abort ();
> +
> + if (foo6 (tmp) != 0x9359)
> + __builtin_abort ();
> +
> + if (foo7 (tmp) != 0x9359)
> + __builtin_abort ();
> +
> + if (foo8 (tmp) != 0x8358)
> + __builtin_abort ();
> +
> + if (foo9 (tmp) != 0x8358)
> + __builtin_abort ();
> +
> + if (foo10 (tmp) != 0x8358)
> + __builtin_abort ();
> +
> + if (foo11 (tmp) != 0x8358)
> + __builtin_abort ();
> +}
> +
> diff --git a/gcc/tree-scalar-evolution.cc b/gcc/tree-scalar-evolution.cc
> index 72ceb4001e3..9b0aec4fd09 100644
> --- a/gcc/tree-scalar-evolution.cc
> +++ b/gcc/tree-scalar-evolution.cc
> @@ -3487,6 +3487,164 @@ expression_expensive_p (tree expr)
> || expanded_size > cache.elements ());
> }
>
> +/* Match.pd function to match bitwise inductive expression.
> + .i.e.
> + _2 = 1 << _1;
> + _3 = ~_2;
> + tmp_9 = _3 & tmp_12; */
> +extern bool gimple_bitwise_induction_p (tree, tree *, tree (*)(tree));
> +
> +/* Return the inductive expression of bitwise operation if possible,
> + otherwise returns DEF. */
> +static tree
> +analyze_and_compute_bitwise_induction_effect (class loop* ex_loop,
> + class loop* loop,
> + tree phidef,
> + tree def,
> + tree niter)
> +{
> + tree match_op[3],inv, bitwise_scev, bitwise_res;
> + bool folded_casts = false;
> + tree type = TREE_TYPE (phidef);
> + gimple* header_phi = NULL;
use a gphi *
> +
> + /* Match things like op2(MATCH_OP[2]), op1(MATCH_OP[1]), phidef(PHIDEF)
> +
> + op2 = PHI <phidef, inv>
> + _1 = (int) bit_17;
> + _3 = 1 << _1;
> + op1 = ~_3;
> + phidef = op1 & op2; */
> + if (!gimple_bitwise_induction_p (phidef, &match_op[0], NULL)
> + || TREE_CODE (match_op[2]) != SSA_NAME
> + || gimple_code (SSA_NAME_DEF_STMT (match_op[2])) != GIMPLE_PHI
|| !(header_phi = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (match_op[2])))
> + || gimple_phi_num_args (SSA_NAME_DEF_STMT (match_op[2])) != 2)
and then use header_phi here, if you pass in the PHI to use you'll
always have 2 args
> + return def;
> +
> + header_phi = SSA_NAME_DEF_STMT (match_op[2]);
> + if (gimple_bb (header_phi) != loop->header)
> + return def;
I think passing in the PHI node and the exit edge instead of phidef
would make the above more clear
> + if (PHI_ARG_DEF_FROM_EDGE (header_phi, loop_latch_edge (loop)) != phidef)
> + return def;
> +
> + inv = gimple_phi_arg_def (header_phi, 0);
> + if (inv == phidef)
> + inv = gimple_phi_arg_def (header_phi, 1);
inv = gimple_phi_arg_def_from_edge (header_phi, loop_preheader_edge (loop));
where is this used?
> +
> + bitwise_scev = analyze_scalar_evolution_in_loop (ex_loop, loop,
> + match_op[1],
> + &folded_casts);
you want
bitwise_scev = analyze_scalar_evolution (loop, match_op[1]);
bitwise_scev = instantiate_parameters (loop, bitwise_scev);
instead since you are interested in in-loop behavior?
> +
> + /* Make sure bits is in range of type precision. */
> + if (TREE_CODE (bitwise_scev) != POLYNOMIAL_CHREC
I think you want to test || !INTEGRAL_TYPE_P (bitwise_scev) since you
do not rule out pointers or vector types.
> + || !tree_fits_uhwi_p (CHREC_LEFT (bitwise_scev))
> + || tree_to_uhwi (CHREC_LEFT (bitwise_scev)) >= TYPE_PRECISION (type)
> + || !tree_fits_shwi_p (CHREC_RIGHT (bitwise_scev)))
> + return def;
> +
> + bitwise_res = compute_overall_effect_of_inner_loop (ex_loop, bitwise_scev);
> + if (!tree_fits_uhwi_p (bitwise_res)
> + || tree_to_uhwi (bitwise_res) >= TYPE_PRECISION (type))
> + return def;
Hmm, so I think that bitwise_res is the final value of the 'bit' IV, correct?
So name it bit_final?
> +
> +enum bit_op_kind
> + {
> + INDUCTION_BIT_CLEAR,
> + INDUCTION_BIT_IOR,
> + INDUCTION_BIT_XOR,
> + INDUCTION_BIT_RESET,
> + INDUCTION_ZERO,
> + INDUCTION_ALL
> + };
> +
> + enum bit_op_kind induction_kind;
> + enum tree_code code1
> + = gimple_assign_rhs_code (SSA_NAME_DEF_STMT (phidef));
> + enum tree_code code2
> + = gimple_assign_rhs_code (SSA_NAME_DEF_STMT (match_op[0]));
> +
> + /* BIT_CLEAR: A &= ~(1 << bit)
> + BIT_RESET: A ^= (1 << bit).
> + BIT_IOR: A |= (1 << bit)
> + BIT_ZERO: A &= (1 << bit)
> + BIT_ALL: A |= ~(1 << bit)
> + BIT_XOR: A ^= ~(1 << bit).
> + bit is induction variable. */
> + switch (code1)
> + {
> + case BIT_AND_EXPR:
> + induction_kind = code2 == BIT_NOT_EXPR
> + ? INDUCTION_BIT_CLEAR
> + : INDUCTION_ZERO;
> + break;
> + case BIT_IOR_EXPR:
> + induction_kind = code2 == BIT_NOT_EXPR
> + ? INDUCTION_ALL
> + : INDUCTION_BIT_IOR;
> + break;
> + case BIT_XOR_EXPR:
> + induction_kind = code2 == BIT_NOT_EXPR
> + ? INDUCTION_BIT_XOR
> + : INDUCTION_BIT_RESET;
> + break;
> + /* A ^ ~(1 << bit) is equal to ~(A ^ (1 << bit)). */
> + case BIT_NOT_EXPR:
> + gcc_assert (code2 == BIT_XOR_EXPR);
> + induction_kind = INDUCTION_BIT_XOR;
> + break;
> + default:
> + gcc_unreachable();
> + }
> +
> + if (induction_kind == INDUCTION_ZERO)
> + return build_zero_cst (type);
is that true even when the loop doesn't iterate?
> + if (induction_kind == INDUCTION_ALL)
> + return build_all_ones_cst (type);
Likewise?
> +
> + wide_int bits = wi::zero (TYPE_PRECISION (type));
> + HOST_WIDE_INT start = tree_to_shwi (CHREC_LEFT (bitwise_scev));
you checked fits_uhwi above, name it bit_start?
> + HOST_WIDE_INT step = tree_to_shwi (CHREC_RIGHT (bitwise_scev));
> + unsigned HOST_WIDE_INT num_iter = tree_to_uhwi (niter);
> +
> + /* Loop tripcount should be num_iter + 1. */
> + for (unsigned i = 0; i != num_iter + 1; i++)
> + {
> + bits = wi::bit_or (bits,
> + wi::lshift (wi::one (TYPE_PRECISION (type)),
> + start));
you can use bits = wi::set_bit (bits, start);
> + start += step;
> + }
Uh. You don't limit 'num_iter' but you limit bit_final. So supposed that
the IV wraps and is unsigned char and you have a 256 bit integer the
above could run quite a long time. Please limit num_iter to TYPE_PRECISION
as well (do you have a testcase with a wrapping IV? try some != CST exit
condition and a large increment)
> +
> + bool inverted = false;
> + switch (induction_kind)
> + {
> + case INDUCTION_BIT_CLEAR:
> + code1 = BIT_AND_EXPR;
> + inverted = true;
> + break;
> + case INDUCTION_BIT_IOR:
> + code1 = BIT_IOR_EXPR;
> + break;
> + case INDUCTION_BIT_RESET:
> + code1 = BIT_XOR_EXPR;
> + break;
> + /* A ^= ~(1 << bit) is special, when loop tripcount is even,
> + it's equal to A ^= bits, else A ^= ~bits. */
> + case INDUCTION_BIT_XOR:
> + code1 = BIT_XOR_EXPR;
> + if (num_iter % 2 == 0)
> + inverted = true;
> + break;
> + default:
> + gcc_unreachable ();
> + }
> +
> + if (inverted)
> + bits = wi::bit_not (bits);
> + return fold_build2 (code1, type, inv, wide_int_to_tree (type, bits));
> +}
> +
> /* Do final value replacement for LOOP, return true if we did anything. */
>
> bool
> @@ -3519,7 +3677,8 @@ final_value_replacement_loop (class loop *loop)
> {
> gphi *phi = psi.phi ();
> tree rslt = PHI_RESULT (phi);
> - tree def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
> + tree phidef = PHI_ARG_DEF_FROM_EDGE (phi, exit);
> + tree def = phidef;
> if (virtual_operand_p (def))
> {
> gsi_next (&psi);
> @@ -3537,6 +3696,23 @@ final_value_replacement_loop (class loop *loop)
> def = analyze_scalar_evolution_in_loop (ex_loop, loop, def,
> &folded_casts);
> def = compute_overall_effect_of_inner_loop (ex_loop, def);
> +
> + /* Handle bitwise induction expression.
> +
> + .i.e.
> + for (int i = 0; i != 64; i+=3)
> + res &= ~(1UL << i);
> +
> + RES can't be analyzed out by SCEV because it is not polynomially
> + expressible, but in fact final value of RES can be replaced by
> + RES & CONSTANT where CONSTANT all ones with bit {0,3,6,9,... ,63}
> + being cleared, similar for BIT_IOR_EXPR/BIT_XOR_EXPR. */
> + if (tree_fits_uhwi_p (niter)
> + && tree_to_uhwi (niter)
that's redundant - ah, it's the not iterating case that's excluded.
please write it
as tree_to_uhwi (niter) != 0, also consider assigning to an unsigned
HOST_WIDE_INT
and pass it that way to analyze_and_compute_bitwise_induction_effect
> + && tree_to_uhwi (niter) != HOST_WIDE_INT_M1U)
> + def = analyze_and_compute_bitwise_induction_effect (ex_loop, loop,
> + phidef, def,
> niter);
> +
it seems you overwrite the SCEV analysis result unconditionally here, please
move this inside of the following if () so it is done as fallback only
(or add it as && !(def = ...) to the condition)
> if (!tree_does_not_contain_chrecs (def)
> || chrec_contains_symbols_defined_in_loop (def, ex_loop->num)
> /* Moving the computation from the loop may prolong life range
> --
> 2.18.1
>
