Hi Andrew, On Fri, Jul 24, 2026 at 3:53 AM Andrea Pinski < [email protected]> wrote:
> On Tue, Jul 14, 2026 at 9:05 AM Konstantinos Eleftheriou > <[email protected]> wrote: > > > > Recognize the longhand wide-multiplication carry idiom and fold it to a > > widening multiply followed by a right shift for the high part, and a > > plain MULT_EXPR for the low part. > > > > The carry idiom is the schoolbook expansion of a 2N-bit unsigned > > multiply written as a top-level + chain of four NxN partial products > > plus one overflow-compare carry: > > > > xh*yh + (cross_sum >> N) + (low_accum >> N) + ((hilo > cross_sum) << N) > > cross_sum = xh*yl + xl*yh > > low_accum = (xl*yl >> N) + (cross_sum & mask) > > > > For example, this AArch64 sequence from SPEC2026's 750.sealcrypto_r: > > > > lsr x4, x0, 32 > > lsr x6, x1, 32 > > umull x3, w0, w1 > > umull x1, w1, w4 > > and x5, x3, 4294967295 > > umaddl x0, w0, w6, x1 > > cmp x1, x0 > > and x1, x0, 4294967295 > > lsr x0, x0, 32 > > add x3, x1, x3, lsr 32 > > cset x1, hi > > orr x5, x5, x3, lsl 32 > > umaddl x4, w4, w6, x0 > > extr x0, x1, x3, 32 > > add x0, x0, x4 > > stp x5, x0, [x2] > > > > can be transformed to: > > > > umulh x3, x1, x0 > > mul x0, x0, x1 > > stp x0, x3, [x2] > > > > Atom-level pattern recognition is implemented via match patterns in > > match.pd (mul_hi, mul_lo, mul_hilo, mul_lolo, mul_hihi, mul_cross_sum, > > mul_low_accum, mul_carry_cross_sum). The composite recognition that > > ties atoms into a long-multiplication chain is performed in forwprop > > by match_long_mul: it linearizes the outer add/ior chain into a > > multiset of summands, classifies each summand via the match.pd atoms, > > and looks the multiset up in long_mul_table to identify the variant. > > On a hit, three cross-summand consistency checks (one operand pair, > > half-width shifts, hilo cross-half products) gate the rewrite. > > > > The HIGH_PART row emits the canonical widening shape > > > > (N)(((2N) op1 * (2N) op2) >> N) > > > > which pass_optimize_widening_mul later lowers to a single > > WIDEN_MULT_EXPR or MULT_HIGHPART_EXPR on targets that support it. > > The LOW_PART row emits a plain MULT_EXPR. HIGH_PART is emitted only > > when the 2N mode is present in the mode table. > > > > Bootstrapped/regtested on AArch64, x86-64 and PowerPC. > > > > PR tree-optimization/107090 > > > > gcc/ChangeLog: > > > > * match.pd: Add atom match recognizers for long-multiply > > (mul_hi, mul_lo, mul_hilo, mul_lolo, mul_hihi, mul_cross_sum, > > mul_low_accum, mul_carry_cross_sum). > > * tree-ssa-forwprop.cc (gimple_mul_hi): Declare. > > (gimple_mul_lo): Likewise. > > (gimple_mul_hilo): Likewise. > > (gimple_mul_lolo): Likewise. > > (gimple_mul_hihi): Likewise. > > (gimple_mul_cross_sum): Likewise. > > (gimple_mul_low_accum): Likewise. > > (gimple_mul_carry_cross_sum): Likewise. > > (create_mul_high_seq): New, emits (N)(((2N) op1 * (2N) op2) >> > N). > > (create_mul_low_seq): New, emits MULT_EXPR. > > (enum long_mul_kind): New. > > (enum long_mul_extract): New. > > (struct long_mul_summand): New. > > (long_mul_linearize_chain): New, walks the outer add/ior chain > > into a multiset of leaves. > > (long_mul_is_lshift_def): New. > > (long_mul_set_summand): New. > > (long_mul_classify_carry): New. > > (long_mul_classify_plus_kinds): New. > > (long_mul_classify_hi_extract): New. > > (long_mul_classify_lo_extract): New. > > (long_mul_classify_shl_extract): New. > > (long_mul_classify_bare): New. > > (long_mul_classify_summand): New, classify each summand via the > > match.pd atoms. > > (long_mul_summand_compare): New. > > (struct long_mul_row): New. > > (long_mul_same_ops): New. > > (long_mul_is_cross_half): New. > > (long_mul_hilo_orientation): New, orientation of a mul_hilo > > capture relative to (op0, op1). > > (long_mul_canonical_ops): New. > > (long_mul_check_consistency): New, cross-summand consistency > > check (operand pairing, half-width shifts, hilo cross-half). > > (long_mul_signature_matches): New. > > (long_mul_hint_shared_intermediate): New, dump-file hint > > pointing at a shared inner addition. > > (match_long_mul): New, top-level entry: linearizes the outer > > add/ior chain, classifies summands, looks the multiset up in > > long_mul_table, runs cross-summand consistency checks, and > > dispatches to create_mul_high_seq / create_mul_low_seq. > > (pass_forwprop::execute): Call match_long_mul on PLUS_EXPR and > > BIT_IOR_EXPR statements. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.dg/tree-ssa/long-mul-carry.c: New test. > > * gcc.target/aarch64/long_mul.c: New test. > > * gcc.target/i386/long_mul.c: New test. > > > > Co-authored-by: Philipp Tomsich <[email protected]> > > Signed-off-by: Konstantinos Eleftheriou < > [email protected]> > > --- > > > > (no changes since v1) > > > > gcc/match.pd | 73 ++ > > .../gcc.dg/tree-ssa/long-mul-carry.c | 181 +++++ > > gcc/testsuite/gcc.target/aarch64/long_mul.c | 58 ++ > > gcc/testsuite/gcc.target/i386/long_mul.c | 58 ++ > > gcc/tree-ssa-forwprop.cc | 701 +++++++++++++++++- > > 5 files changed, 1066 insertions(+), 5 deletions(-) > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/long-mul-carry.c > > create mode 100644 gcc/testsuite/gcc.target/aarch64/long_mul.c > > create mode 100644 gcc/testsuite/gcc.target/i386/long_mul.c > > > > diff --git a/gcc/match.pd b/gcc/match.pd > > index 9d4ab622fe57..5a4b1923b589 100644 > > --- a/gcc/match.pd > > +++ b/gcc/match.pd > > @@ -12160,6 +12160,79 @@ and, > > INTEGER_CST@2) INTEGER_CST@3) > > (if (compare_tree_int (@sub1, 1) == 0))) > > > > +#if GIMPLE > > +/* Match low and high parts of longhand multiplication. > > + Given a 2N-bit unsigned type, x = xh*2^N + xl and y = yh*2^N + yl, > > + where xh, xl, yh, yl are N-bit halves extracted via shifts and > masks. */ > > + > > +/* High half: op >> N. */ > > +(match (mul_hi @op @0) > > + (rshift @op INTEGER_CST@0) > > + (with { > > + tree op_type = TREE_TYPE (@op); } > > + (if (INTEGRAL_TYPE_P (op_type) > > + && TYPE_UNSIGNED (op_type) > > + && TYPE_PRECISION (op_type) % 2 == 0 > > + && tree_fits_uhwi_p (@0) > > + && tree_to_uhwi (@0) == TYPE_PRECISION (op_type) / 2)))) > > +/* Low half: op & mask. */ > > +(match (mul_lo @op @0) > > + (bit_and @op INTEGER_CST@0) > > + (with { > > + tree op_type = TREE_TYPE (@op); } > > + (if (INTEGRAL_TYPE_P (op_type) > > + && TYPE_UNSIGNED (op_type) > > + && TYPE_PRECISION (op_type) % 2 == 0 > > + && tree_fits_uhwi_p (@0) > > + && tree_to_uhwi (@0) == wi::mask ( > > + TYPE_PRECISION (op_type) / 2, > > + false, > > + TYPE_PRECISION (op_type)))))) > > +/* Cross product: high(op0) * low(op1). */ > > +(match (mul_hilo @op0 @op1 @0 @1) > > + (mult:c > > + (mul_hi @op0 INTEGER_CST@0) > > + (mul_lo @op1 INTEGER_CST@1))) > > +/* Low-low product: low(op0) * low(op1). */ > > +(match (mul_lolo @op0 @op1 @0) > > + (mult:c > > + (mul_lo @op0 INTEGER_CST@0) > > + (mul_lo @op1 INTEGER_CST@0))) > > +/* High-high product: high(op0) * high(op1). */ > > +(match (mul_hihi @op0 @op1 @0) > > + (mult:c > > + (mul_hi @op0 INTEGER_CST@0) > > + (mul_hi @op1 INTEGER_CST@0))) > > +/* Cross sum: xh*yl + xl*yh. > > + Note: matches any PLUS; operands are validated as actual cross > > + products by the forwprop consumer (long_mul_check_consistency). */ > > +(match (mul_cross_sum @mul_hilo0 @mul_hilo1) > > + (plus:c @mul_hilo0 @mul_hilo1)) > > +/* Carry from cross-sum overflow: (cast?) (hilo > cross_sum) << N. > > + Explicit guard required because mul_cross_sum is just (plus:c @0 @1) > > + with no inherent type or halfwidth constraint. */ > > +(match (mul_carry_cross_sum @mul_hilo0 @mul_hilo1 @mul_hilo2 @0) > > + (lshift > > + (convert? (gt > > + @mul_hilo0 > > + (mul_cross_sum @mul_hilo1 @mul_hilo2))) > > + INTEGER_CST@0) > > + (with { > > + tree op_type = TREE_TYPE (@mul_hilo0); } > > + (if (INTEGRAL_TYPE_P (op_type) > > + && TYPE_UNSIGNED (op_type) > > + && TYPE_PRECISION (op_type) % 2 == 0 > > + && tree_fits_uhwi_p (@0) > > + && tree_to_uhwi (@0) == TYPE_PRECISION (op_type) / 2)))) > > +/* Low accumulate: (xl*yl >> N) + (cross_sum & mask). */ > > +(match (mul_low_accum @op0 @op1 @mul_hilo0 @mul_hilo1 @0 @1) > > + (plus:c > > + (mul_hi > > + (mul_lolo @op0 @op1 INTEGER_CST@0) > > + INTEGER_CST@1) > > + (mul_lo (mul_cross_sum @mul_hilo0 @mul_hilo1) INTEGER_CST@0))) > > +#endif > > + > > /* Floatint point/integer comparison and integer->integer > > or floating point -> float point conversion. */ > > (match (cond_expr_convert_p @0 @2 @3 @6) > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/long-mul-carry.c > b/gcc/testsuite/gcc.dg/tree-ssa/long-mul-carry.c > > new file mode 100644 > > index 000000000000..bbdbc63ac0bb > > --- /dev/null > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/long-mul-carry.c > > @@ -0,0 +1,181 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O3 -fdump-tree-forwprop-details" } */ > > + > > +typedef __UINT32_TYPE__ uint32_t; > > +typedef __UINT64_TYPE__ uint64_t; > > +typedef struct { uint32_t v[2]; } v2i32; > > + > > +/* High part follows the long form > > + xh*yh + carry + (cross_sum >> N) + (low_accum >> N). */ > > + > > +uint64_t mulh_carry (uint64_t x, uint64_t y) > > +{ > > + uint64_t x_lo = x & 0xFFFFFFFF; > > + uint64_t x_hi = x >> 32; > > + uint64_t y_lo = y & 0xFFFFFFFF; > > + uint64_t y_hi = y >> 32; > > + uint64_t y_lo_x_hi = y_lo * x_hi; > > + uint64_t y_hi_x_hi = y_hi * x_hi; > > + uint64_t y_hi_x_lo = y_hi * x_lo; > > + uint64_t y_lo_x_lo = y_lo * x_lo; > > + uint64_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = cross_sum < y_lo_x_hi; > > + uint64_t carry = (uint64_t) carry_out << 32; > > + uint64_t y_lo_x_lo_hi = y_lo_x_lo >> 32; > > + uint64_t cross_sum_lo = cross_sum & 0xFFFFFFFF; > > + uint64_t cross_sum_hi = cross_sum >> 32; > > + uint64_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint64_t interm = cross_sum_hi + y_hi_x_hi; > > + uint64_t low_accum_hi = low_accum >> 32; > > + uint64_t interm_plus_carry = interm + carry; > > + uint64_t hw64 = interm_plus_carry + low_accum_hi; > > + > > + return hw64; > > +} > > + > > +uint64_t mulh_carry_comm (uint64_t x, uint64_t y) > > +{ > > + uint64_t x_lo = x & 0xFFFFFFFF; > > + uint64_t y_lo = y & 0xFFFFFFFF; > > + uint64_t x_hi = x >> 32; > > + uint64_t y_hi = y >> 32; > > + uint64_t y_lo_x_hi = x_hi * y_lo; > > + uint64_t y_hi_x_hi = y_hi * x_hi; > > + uint64_t y_hi_x_lo = x_lo * y_hi; > > + uint64_t y_lo_x_lo = x_lo * y_lo; > > + uint64_t cross_sum = y_lo_x_hi + y_hi_x_lo; > > + int carry_out = (cross_sum < y_lo_x_hi); > > + uint64_t carry = (uint64_t) carry_out << 32; > > + uint64_t y_lo_x_lo_hi = y_lo_x_lo >> 32; > > + uint64_t cross_sum_lo = cross_sum & 0xFFFFFFFF; > > + uint64_t cross_sum_hi = cross_sum >> 32; > > + uint64_t low_accum = y_lo_x_lo_hi + cross_sum_lo; > > + uint64_t inter = y_hi_x_hi + cross_sum_hi; > > + uint64_t low_accum_hi = low_accum >> 32; > > + uint64_t interm_plus_carry = carry + inter; > > + uint64_t hw64 = low_accum_hi + interm_plus_carry; > > + > > + return hw64; > > +} > > + > > +uint32_t mulh_carry_32 (uint32_t x, uint32_t y) > > +{ > > + uint32_t x_lo = x & 0xFFFF; > > + uint32_t x_hi = x >> 16; > > + uint32_t y_lo = y & 0xFFFF; > > + uint32_t y_hi = y >> 16; > > + uint32_t y_lo_x_hi = y_lo * x_hi; > > + uint32_t y_hi_x_hi = y_hi * x_hi; > > + uint32_t y_hi_x_lo = y_hi * x_lo; > > + uint32_t y_lo_x_lo = y_lo * x_lo; > > + uint32_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = (cross_sum < y_lo_x_hi); > > + uint32_t carry = (uint32_t) carry_out << 16; > > + uint32_t y_lo_x_lo_hi = y_lo_x_lo >> 16; > > + uint32_t cross_sum_lo = cross_sum & 0xFFFF; > > + uint32_t cross_sum_hi = cross_sum >> 16; > > + uint32_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint32_t interm = cross_sum_hi + y_hi_x_hi; > > + uint32_t low_accum_hi = low_accum >> 16; > > + uint32_t interm_plus_carry = interm + carry; > > + uint32_t hw64 = interm_plus_carry + low_accum_hi; > > + > > + return hw64; > > +} > > + > > +/* The 128-bit variant lowers to longhand in pass_optimize_widening_mul; > > + no target provides a 256-bit multiply. */ > > +#ifdef __SIZEOF_INT128__ > > +__uint128_t mulh_carry_128 (__uint128_t x, __uint128_t y) > > +{ > > + __uint128_t x_lo = x & (__uint128_t)0xFFFFFFFFFFFFFFFF; > > + __uint128_t x_hi = x >> 64; > > + __uint128_t y_lo = y & (__uint128_t)0xFFFFFFFFFFFFFFFF; > > + __uint128_t y_hi = y >> 64; > > + __uint128_t y_lo_x_hi = y_lo * x_hi; > > + __uint128_t y_hi_x_hi = y_hi * x_hi; > > + __uint128_t y_hi_x_lo = y_hi * x_lo; > > + __uint128_t y_lo_x_lo = y_lo * x_lo; > > + __uint128_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = cross_sum < y_lo_x_hi; > > + __uint128_t carry = (__uint128_t) carry_out << 64; > > + __uint128_t y_lo_x_lo_hi = y_lo_x_lo >> 64; > > + __uint128_t cross_sum_lo = cross_sum & > (__uint128_t)0xFFFFFFFFFFFFFFFF; > > + __uint128_t cross_sum_hi = cross_sum >> 64; > > + __uint128_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + __uint128_t interm = cross_sum_hi + y_hi_x_hi; > > + __uint128_t low_accum_hi = low_accum >> 64; > > + __uint128_t interm_plus_carry = interm + carry; > > + __uint128_t hw64 = interm_plus_carry + low_accum_hi; > > + > > + return hw64; > > +} > > +#endif > > + > > +void full_mul_carry (uint64_t x, uint64_t y, uint64_t* p) { > > + uint64_t x_lo = x & 0xFFFFFFFF; > > + uint64_t y_lo = y & 0xFFFFFFFF; > > + uint64_t x_hi = x >> 32; > > + uint64_t y_hi = y >> 32; > > + uint64_t y_lo_x_hi = y_lo * x_hi; > > + uint64_t y_hi_x_hi = y_hi * x_hi; > > + uint64_t y_hi_x_lo = y_hi * x_lo; > > + uint64_t y_lo_x_lo = y_lo * x_lo; > > + uint64_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = (cross_sum < y_lo_x_hi); > > + uint64_t carry = (uint64_t) carry_out << 32; > > + uint64_t y_lo_x_lo_hi = y_lo_x_lo >> 32; > > + uint64_t cross_sum_lo = cross_sum & 0xFFFFFFFF; > > + uint64_t cross_sum_hi = cross_sum >> 32; > > + uint64_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint64_t upper_mid = y_hi_x_hi + carry; > > + uint64_t low_accum_hi = low_accum >> 32; > > + uint64_t upper_mid_with_cross = upper_mid + cross_sum_hi; > > + uint64_t hw64 = upper_mid_with_cross + low_accum_hi; > > + p[1] = hw64; > > + uint64_t low_accum_shifted = low_accum << 32; > > + uint64_t y_lo_x_lo_lo = y_lo_x_lo & 0xFFFFFFFF; > > + uint64_t lw64 = low_accum_shifted | y_lo_x_lo_lo; > > + p[0] = lw64; > > +} > > + > > +/* This will be optimized during the second forwprop run. > > + Disable SLP so the expected fold count is target-independent. */ > > +__attribute__((optimize("no-tree-slp-vectorize"))) > > +v2i32 mulh_carry_v2i32 (v2i32 x, v2i32 y) > > +{ > > + v2i32 result; > > + for (int i = 0; i < 2; i++) > > + { > > + uint32_t x_lo = x.v[i] & 0xFFFF; > > + uint32_t y_lo = y.v[i] & 0xFFFF; > > + uint32_t x_hi = x.v[i] >> 16; > > + uint32_t y_hi = y.v[i] >> 16; > > + > > + uint32_t y_lo_x_hi = y_lo * x_hi; > > + uint32_t y_hi_x_hi = y_hi * x_hi; > > + uint32_t y_hi_x_lo = y_hi * x_lo; > > + uint32_t y_lo_x_lo = y_lo * x_lo; > > + > > + uint32_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = cross_sum < y_lo_x_hi; > > + uint32_t carry = (uint32_t) carry_out << 16; > > + > > + uint32_t y_lo_x_lo_hi = y_lo_x_lo >> 16; > > + uint32_t cross_sum_lo = cross_sum & 0xFFFF; > > + uint32_t cross_sum_hi = cross_sum >> 16; > > + > > + uint32_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint32_t interm = cross_sum_hi + y_hi_x_hi; > > + uint32_t low_accum_hi = low_accum >> 16; > > + uint32_t interm_plus_carry = interm + carry; > > + > > + result.v[i] = interm_plus_carry + low_accum_hi; > > + } > > + > > + return result; > > +} > > + > > +/* { dg-final { scan-tree-dump-times "Long multiplication high part > folded." 4 "forwprop1" } } */ > > +/* { dg-final { scan-tree-dump-times "Long multiplication high part > folded." 1 "forwprop2" } } */ > > +/* { dg-final { scan-tree-dump-times "Long multiplication low part > folded." 1 "forwprop1" } } */ > > diff --git a/gcc/testsuite/gcc.target/aarch64/long_mul.c > b/gcc/testsuite/gcc.target/aarch64/long_mul.c > > new file mode 100644 > > index 000000000000..2a4709ecbfd0 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/aarch64/long_mul.c > > @@ -0,0 +1,58 @@ > > +/* { dg-do compile } */ > > +/* { dg-options "-O3" } */ > > + > > +typedef __UINT32_TYPE__ uint32_t; > > +typedef __UINT64_TYPE__ uint64_t; > > + > > +/* 64-bit carry pattern for high part. */ > > +uint64_t mulh_carry (uint64_t x, uint64_t y) > > +{ > > + uint64_t x_lo = x & 0xFFFFFFFF; > > + uint64_t x_hi = x >> 32; > > + uint64_t y_lo = y & 0xFFFFFFFF; > > + uint64_t y_hi = y >> 32; > > + uint64_t y_lo_x_hi = y_lo * x_hi; > > + uint64_t y_hi_x_hi = y_hi * x_hi; > > + uint64_t y_hi_x_lo = y_hi * x_lo; > > + uint64_t y_lo_x_lo = y_lo * x_lo; > > + uint64_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = cross_sum < y_lo_x_hi; > > + uint64_t carry = (uint64_t) carry_out << 32; > > + uint64_t y_lo_x_lo_hi = y_lo_x_lo >> 32; > > + uint64_t cross_sum_lo = cross_sum & 0xFFFFFFFF; > > + uint64_t cross_sum_hi = cross_sum >> 32; > > + uint64_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint64_t interm = cross_sum_hi + y_hi_x_hi; > > + uint64_t low_accum_hi = low_accum >> 32; > > + uint64_t interm_plus_carry = interm + carry; > > + return interm_plus_carry + low_accum_hi; > > +} > > + > > +/* 32-bit carry pattern for high part. */ > > +uint32_t mulh_carry_32 (uint32_t x, uint32_t y) > > +{ > > + uint32_t x_lo = x & 0xFFFF; > > + uint32_t x_hi = x >> 16; > > + uint32_t y_lo = y & 0xFFFF; > > + uint32_t y_hi = y >> 16; > > + uint32_t y_lo_x_hi = y_lo * x_hi; > > + uint32_t y_hi_x_hi = y_hi * x_hi; > > + uint32_t y_hi_x_lo = y_hi * x_lo; > > + uint32_t y_lo_x_lo = y_lo * x_lo; > > + uint32_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = (cross_sum < y_lo_x_hi); > > + uint32_t carry = (uint32_t) carry_out << 16; > > + uint32_t y_lo_x_lo_hi = y_lo_x_lo >> 16; > > + uint32_t cross_sum_lo = cross_sum & 0xFFFF; > > + uint32_t cross_sum_hi = cross_sum >> 16; > > + uint32_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint32_t interm = cross_sum_hi + y_hi_x_hi; > > + uint32_t low_accum_hi = low_accum >> 16; > > + uint32_t interm_plus_carry = interm + carry; > > + return interm_plus_carry + low_accum_hi; > > +} > > + > > +/* 64-bit pattern should emit umulh. */ > > +/* { dg-final { scan-assembler-times "umulh\t" 1 } } */ > > +/* 32-bit pattern should emit umull (32x32->64 widening multiply). */ > > +/* { dg-final { scan-assembler-times "umull\t" 1 } } */ > > diff --git a/gcc/testsuite/gcc.target/i386/long_mul.c > b/gcc/testsuite/gcc.target/i386/long_mul.c > > new file mode 100644 > > index 000000000000..6ec87eb8dd21 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/i386/long_mul.c > > @@ -0,0 +1,58 @@ > > +/* { dg-do compile { target { ! ia32 } } } */ > > +/* { dg-options "-O3" } */ > > + > > +typedef __UINT32_TYPE__ uint32_t; > > +typedef __UINT64_TYPE__ uint64_t; > > + > > +/* 64-bit carry pattern for high part. */ > > +uint64_t mulh_carry (uint64_t x, uint64_t y) > > +{ > > + uint64_t x_lo = x & 0xFFFFFFFF; > > + uint64_t x_hi = x >> 32; > > + uint64_t y_lo = y & 0xFFFFFFFF; > > + uint64_t y_hi = y >> 32; > > + uint64_t y_lo_x_hi = y_lo * x_hi; > > + uint64_t y_hi_x_hi = y_hi * x_hi; > > + uint64_t y_hi_x_lo = y_hi * x_lo; > > + uint64_t y_lo_x_lo = y_lo * x_lo; > > + uint64_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = cross_sum < y_lo_x_hi; > > + uint64_t carry = (uint64_t) carry_out << 32; > > + uint64_t y_lo_x_lo_hi = y_lo_x_lo >> 32; > > + uint64_t cross_sum_lo = cross_sum & 0xFFFFFFFF; > > + uint64_t cross_sum_hi = cross_sum >> 32; > > + uint64_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint64_t interm = cross_sum_hi + y_hi_x_hi; > > + uint64_t low_accum_hi = low_accum >> 32; > > + uint64_t interm_plus_carry = interm + carry; > > + return interm_plus_carry + low_accum_hi; > > +} > > + > > +/* 32-bit carry pattern for high part. */ > > +uint32_t mulh_carry_32 (uint32_t x, uint32_t y) > > +{ > > + uint32_t x_lo = x & 0xFFFF; > > + uint32_t x_hi = x >> 16; > > + uint32_t y_lo = y & 0xFFFF; > > + uint32_t y_hi = y >> 16; > > + uint32_t y_lo_x_hi = y_lo * x_hi; > > + uint32_t y_hi_x_hi = y_hi * x_hi; > > + uint32_t y_hi_x_lo = y_hi * x_lo; > > + uint32_t y_lo_x_lo = y_lo * x_lo; > > + uint32_t cross_sum = y_hi_x_lo + y_lo_x_hi; > > + int carry_out = (cross_sum < y_lo_x_hi); > > + uint32_t carry = (uint32_t) carry_out << 16; > > + uint32_t y_lo_x_lo_hi = y_lo_x_lo >> 16; > > + uint32_t cross_sum_lo = cross_sum & 0xFFFF; > > + uint32_t cross_sum_hi = cross_sum >> 16; > > + uint32_t low_accum = cross_sum_lo + y_lo_x_lo_hi; > > + uint32_t interm = cross_sum_hi + y_hi_x_hi; > > + uint32_t low_accum_hi = low_accum >> 16; > > + uint32_t interm_plus_carry = interm + carry; > > + return interm_plus_carry + low_accum_hi; > > +} > > + > > +/* 64-bit pattern should emit mulq (unsigned 64x64->128 multiply). */ > > +/* { dg-final { scan-assembler-times "\tmulq" 1 } } */ > > +/* 32-bit pattern should emit imulq (64-bit multiply of zero-extended > operands). */ > > +/* { dg-final { scan-assembler-times "\timulq" 1 } } */ > > diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc > > index 12c07c99c9bd..3870bf17c0e0 100644 > > --- a/gcc/tree-ssa-forwprop.cc > > +++ b/gcc/tree-ssa-forwprop.cc > > @@ -3592,6 +3592,693 @@ simplify_count_zeroes (gimple_stmt_iterator *gsi) > > return true; > > } > > > > +/* Match.pd functions to match long multiplication. */ > > + > > +extern bool gimple_mul_hi (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_lo (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_hilo (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_lolo (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_hihi (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_cross_sum (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_low_accum (tree, tree *, tree (*)(tree)); > > +extern bool gimple_mul_carry_cross_sum (tree, tree *, tree (*)(tree)); > > + > > +/* Replace STMT with a high-part multiply of OP1 and OP2, emitted as > > + (N)(((2N) op1 * (2N) op2) >> N). > > + pass_optimize_widening_mul's convert_mult_to_widen and > > + convert_mult_to_highpart later rewrite this to a single > > + WIDEN_MULT_EXPR or MULT_HIGHPART_EXPR when the target supports it, > > + otherwise the 2N multiply expands directly. Emitting the canonical > > + widening shape keeps target-capability decisions in the layer that > > + already owns them. */ > > + > > +static void > > +create_mul_high_seq (tree op1, tree op2, gimple *stmt) > > +{ > > + tree op_type = TREE_TYPE (op1); > > + unsigned int width = TYPE_PRECISION (op_type); > > + tree wide_type = build_nonstandard_integer_type (width * 2, 1); > > + > > + location_t loc = gimple_location (stmt); > > + gimple_seq seq = NULL; > > + > > + tree wide_a = gimple_convert (&seq, loc, wide_type, op1); > > + tree wide_b = gimple_convert (&seq, loc, wide_type, op2); > > + tree wide_prod = gimple_build (&seq, loc, MULT_EXPR, wide_type, > > + wide_a, wide_b); > > + tree hi = gimple_build (&seq, loc, RSHIFT_EXPR, wide_type, wide_prod, > > + build_int_cst (integer_type_node, width)); > > + > > + gimple *prod = gimple_build_assign (gimple_get_lhs (stmt), NOP_EXPR, > hi); > > + gimple_set_location (prod, loc); > > + gimple_seq_add_stmt (&seq, prod); > > + > > + gimple_stmt_iterator gsi = gsi_for_stmt (stmt); > > + gsi_replace_with_seq (&gsi, seq, true); > > +} > > + > > +/* Replace STMT with a low-part multiply of OP1 and OP2. */ > > + > > +static void > > +create_mul_low_seq (tree op1, tree op2, gimple *stmt) > > +{ > > + gimple *prod = gimple_build_assign (gimple_get_lhs (stmt), > > + MULT_EXPR, op1, op2); > > + gimple_set_location (prod, gimple_location (stmt)); > > + gimple_stmt_iterator gsi = gsi_for_stmt (stmt); > > + gsi_replace (&gsi, prod, true); > > +} > > + > > +/* Long-multiply fold framework. > > + > > + Walks the outer addition or bit_ior chain on a candidate statement, > > + classifies each summand against the atom match patterns from > > + match.pd, and looks the resulting multiset of (kind, extract) tuples > > + up in a table. On a hit, three cross-summand consistency checks > > + decide whether the wide multiply is emitted. */ > > + > > +/* Widest match.pd atom (mul_low_accum) takes 6 captures; round up > > + to 8 for the scratch buffers below. */ > > +static constexpr unsigned LONG_MUL_MAX_CAPTURES = 8; > > + > > +/* Longest variant in long_mul_table has 4 summands. */ > > +static constexpr unsigned LONG_MUL_MAX_SUMMANDS = 4; > > + > > +enum long_mul_kind { > > + LMK_MUL_HIHI, > > + LMK_MUL_LOLO, > > + LMK_MUL_HILO, > > + LMK_CROSS_SUM, > > + LMK_LOW_ACCUM, > > + LMK_CARRY_CROSS_SUM, > > +}; > > + > > +/* How the leaf wraps its inner kind. Carry kinds use LMX_NONE: their > > + match.pd pattern bakes the lshift in, so the leaf is already the > > + complete carry expression. */ > > + > > +enum long_mul_extract { > > + LMX_NONE, > > + LMX_HI, > > + LMX_LO, > > + LMX_SHL_N, > > +}; > > + > > +struct long_mul_summand { > > + long_mul_kind kind; > > + long_mul_extract extract; > > + tree op0, op1; > > + tree hilo0, hilo1, hilo2; > > + unsigned HOST_WIDE_INT shift; > > + unsigned HOST_WIDE_INT mask; > > +}; > > + > > +/* Walk the OUTER addition or BIT_IOR chain rooted at STMT and collect > > + the leaf operands into LEAVES. Descends through single-use > > + intermediate stmts of the same code. Returns false once the leaf > > + count exceeds LONG_MUL_MAX_SUMMANDS, so an overlong chain bails > > + mid-walk instead of after a full traversal. > > + > > + If SHARED_DEF_OUT is non-NULL, record there the first inner stmt that > > + shares the outer code but has more than one use -- descending into it > > + would change semantics, so it stays as a leaf. Such a leaf often > > + classifies as something no row matches, silently disabling the fold; > > + the caller surfaces this as a dump-file hint. */ > > + > > +static bool > > +long_mul_linearize_chain (gimple *stmt, tree_code outer, vec<tree> > &leaves, > > + gimple **shared_def_out = NULL) > > +{ > > + auto_vec<tree, 8> stack; > > + stack.safe_push (gimple_assign_rhs2 (stmt)); > > + stack.safe_push (gimple_assign_rhs1 (stmt)); > > + > > + while (!stack.is_empty ()) > > + { > > The biggest problem I have with this patch is why do you need a worklist > here? > That's not a worklist. It's a one-shot linearization of a single associative PLUS/OR into its summands. It runs once per root, holds at most 4 entries, and doesn't revisit statements. > Since you are looking backwards and forwprop will retry the statement > if returns changed. > There are no intermediate changes. We're not folding anything until the whole pattern matches. > Do we need a worklist at all? > We need the linearization. Recognition is a multiset lookup: we collect all summands, sort them, and look the signature up in `long_mul_table`. A single summand (xh*yh, a cross-sum) matches no row, so there's nothing to fold incrementally. > > Shouldn't we just do a simple matching for the leaf? and then handle > that case first and then retry? > The chain is associativity/commutativity-variant. Flatten + sort lets one table row cover every shape. Matching immediate operands only would push that into a combinatorial set of patterns. > This has been my biggest concern for even the original patch which is > why I wanted to see it split up to see if you could remove it. > We could add a comment to clarify this. Thanks, Konstantinos > > + tree t = stack.pop (); > > + if (TREE_CODE (t) == SSA_NAME) > > + { > > + gimple *def = SSA_NAME_DEF_STMT (t); > > + if (def > > + && is_gimple_assign (def) > > + && gimple_assign_rhs_code (def) == outer) > > + { > > + if (has_single_use (t)) > > + { > > + stack.safe_push (gimple_assign_rhs2 (def)); > > + stack.safe_push (gimple_assign_rhs1 (def)); > > + continue; > > + } > > + if (shared_def_out && !*shared_def_out) > > + *shared_def_out = def; > > + } > > + } > > + leaves.safe_push (t); > > + if (leaves.length () > LONG_MUL_MAX_SUMMANDS) > > + return false; > > + } > > + return !leaves.is_empty (); > > +} > > + > > +/* If EXPR is defined by LSHIFT_EXPR with a uhwi-valued amount, return > > + the shifted input via *INNER_OUT and the amount via *SHIFT_OUT. */ > > + > > +static bool > > +long_mul_is_lshift_def (tree expr, tree *inner_out, > > + unsigned HOST_WIDE_INT *shift_out) > > +{ > > + if (TREE_CODE (expr) != SSA_NAME) > > + return false; > > + gimple *def = SSA_NAME_DEF_STMT (expr); > > + if (!def || !is_gimple_assign (def) > > + || gimple_assign_rhs_code (def) != LSHIFT_EXPR) > > + return false; > > + tree amount = gimple_assign_rhs2 (def); > > + if (!tree_fits_uhwi_p (amount)) > > + return false; > > + *inner_out = gimple_assign_rhs1 (def); > > + *shift_out = tree_to_uhwi (amount); > > + return true; > > +} > > + > > +/* Fill INFO's kind plus the captures from RES_OPS that the kind > requires. > > + The kind itself determines how many (op0, op1) and hilo captures to > > + pick up from RES_OPS, and whether a baked-in shift is present. */ > > + > > +static void > > +long_mul_set_summand (long_mul_summand *info, long_mul_kind kind, > > + const tree *res_ops) > > +{ > > + info->kind = kind; > > + unsigned n_ops = 0; > > + unsigned n_hilos = 0; > > + int shift_idx = -1; > > + switch (kind) > > + { > > + case LMK_MUL_HIHI: > > + case LMK_MUL_LOLO: > > + case LMK_MUL_HILO: > > + n_ops = 2; > > + break; > > + case LMK_CROSS_SUM: > > + n_hilos = 2; > > + break; > > + case LMK_LOW_ACCUM: > > + n_ops = 2; > > + n_hilos = 2; > > + break; > > + case LMK_CARRY_CROSS_SUM: > > + n_hilos = 3; > > + shift_idx = 3; > > + break; > > + } > > + if (n_ops >= 1) > > + info->op0 = res_ops[0]; > > + if (n_ops >= 2) > > + info->op1 = res_ops[1]; > > + if (n_hilos >= 1) > > + info->hilo0 = res_ops[n_ops]; > > + if (n_hilos >= 2) > > + info->hilo1 = res_ops[n_ops + 1]; > > + if (n_hilos >= 3) > > + info->hilo2 = res_ops[n_ops + 2]; > > + if (shift_idx >= 0) > > + info->shift = tree_to_uhwi (res_ops[shift_idx]); > > +} > > + > > +/* Classify LEAF as a carry-kind summand. The lshift amount is baked > > + into mul_carry_cross_sum, so it's tried before any branch that looks > > + for a generic (X >> N) or (X << N) wrapper. */ > > + > > +static bool > > +long_mul_classify_carry (tree leaf, long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + if (gimple_mul_carry_cross_sum (leaf, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_CARRY_CROSS_SUM, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Plus-based summand kinds shared by the (X >> SHIFT) and (X << SHIFT) > > + classifiers. */ > > + > > +static bool > > +long_mul_classify_plus_kinds (tree inner, long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + if (gimple_mul_low_accum (inner, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_LOW_ACCUM, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Classify INNER -- already unwrapped from an outer (X >> SHIFT) -- as > > + a high-half-extracted summand. mul_hilo (mult-shape) is orthogonal > > + to the plus-based kinds and is tried first; mul_cross_sum (any plus) > > + is the fallback after the shared plus-based kinds. */ > > + > > +static bool > > +long_mul_classify_hi_extract (tree inner, unsigned HOST_WIDE_INT shift, > > + long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + info->extract = LMX_HI; > > + info->shift = shift; > > + if (gimple_mul_hilo (inner, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_MUL_HILO, res_ops); > > + return true; > > + } > > + if (long_mul_classify_plus_kinds (inner, info)) > > + return true; > > + if (gimple_mul_cross_sum (inner, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_CROSS_SUM, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Classify INNER -- already unwrapped from an outer (X & MASK) -- as > > + a low-half-masked summand. */ > > + > > +static bool > > +long_mul_classify_lo_extract (tree inner, unsigned HOST_WIDE_INT mask, > > + long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + info->extract = LMX_LO; > > + info->mask = mask; > > + if (gimple_mul_lolo (inner, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_MUL_LOLO, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Classify INNER -- already unwrapped from an outer (X << SHIFT) -- as > > + a left-shifted summand. No mul_hilo here -- that shape appears only > > + under (X >> SHIFT). */ > > + > > +static bool > > +long_mul_classify_shl_extract (tree inner, unsigned HOST_WIDE_INT shift, > > + long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + info->extract = LMX_SHL_N; > > + info->shift = shift; > > + if (long_mul_classify_plus_kinds (inner, info)) > > + return true; > > + if (gimple_mul_cross_sum (inner, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_CROSS_SUM, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Classify LEAF as one of the bare-kind summands (no extraction > > + wrapper): mul_hihi or mul_lolo standing on their own. */ > > + > > +static bool > > +long_mul_classify_bare (tree leaf, long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + if (gimple_mul_hihi (leaf, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_MUL_HIHI, res_ops); > > + return true; > > + } > > + if (gimple_mul_lolo (leaf, res_ops, NULL)) > > + { > > + long_mul_set_summand (info, LMK_MUL_LOLO, res_ops); > > + return true; > > + } > > + return false; > > +} > > + > > +/* Classify LEAF as one of the long-multiply summand shapes. On > success, > > + fill *INFO with the kind, extract, captured operands and shift/mask. > > + Dispatches to per-extract helpers; the order matters because the > > + carry kinds bake an lshift into the pattern and would otherwise be > > + misread by the (X << N) branch. */ > > + > > +static bool > > +long_mul_classify_summand (tree leaf, long_mul_summand *info) > > +{ > > + tree res_ops[LONG_MUL_MAX_CAPTURES]; > > + *info = {}; > > + > > + if (long_mul_classify_carry (leaf, info)) > > + return true; > > + > > + if (gimple_mul_hi (leaf, res_ops, NULL)) > > + return long_mul_classify_hi_extract (res_ops[0], > > + tree_to_uhwi (res_ops[1]), > info); > > + > > + if (gimple_mul_lo (leaf, res_ops, NULL)) > > + return long_mul_classify_lo_extract (res_ops[0], > > + tree_to_uhwi (res_ops[1]), > info); > > + > > + tree inner; > > + unsigned HOST_WIDE_INT shift; > > + if (long_mul_is_lshift_def (leaf, &inner, &shift)) > > + return long_mul_classify_shl_extract (inner, shift, info); > > + > > + return long_mul_classify_bare (leaf, info); > > +} > > + > > +/* qsort comparator: sort summands by (kind, extract) to put a multiset > > + into canonical order for table lookup. Unstable sort within a tie is > > + harmless: no row in long_mul_table pairs distinct subterms under the > > + same (kind, extract), and long_mul_check_consistency cross-validates > > + that matching summands share one canonical (op0, op1). */ > > + > > +static int > > +long_mul_summand_compare (const void *a, const void *b) > > +{ > > + const long_mul_summand *sa = (const long_mul_summand *) a; > > + const long_mul_summand *sb = (const long_mul_summand *) b; > > + if (sa->kind != sb->kind) > > + return (int) sa->kind - (int) sb->kind; > > + return (int) sa->extract - (int) sb->extract; > > +} > > + > > +/* One row of the long-multiply variant table. COUNT is how many > entries > > + of SIG carry the row's signature (2 to LONG_MUL_MAX_SUMMANDS); a row > > + with fewer summands leaves the remaining SIG entries > zero-initialized. > > + Those zeros are not a terminator -- {LMK_MUL_HIHI, LMX_NONE} is > itself a > > + valid signature -- so long_mul_signature_matches is bounded by COUNT, > > + never by a sentinel entry. */ > > + > > +struct long_mul_row { > > + enum long_mul_row_part { HIGH_PART, LOW_PART } part; > > + tree_code outer; > > + unsigned char count; > > + struct { > > + long_mul_kind kind; > > + long_mul_extract extract; > > + } sig[LONG_MUL_MAX_SUMMANDS]; > > + bool (*extra_check) (const vec<long_mul_summand> &, gimple *); > > +}; > > + > > +/* True if (A, B) is the same pair as (OP0, OP1) in either order. */ > > + > > +static inline bool > > +long_mul_same_ops (tree a, tree b, tree op0, tree op1) > > +{ > > + return (a == op0 && b == op1) || (a == op1 && b == op0); > > +} > > + > > +/* True if H is a cross-half product of (OP0, OP1) -- gimple_mul_hilo > > + recognizes it and its captured operands match the pair. */ > > + > > +static bool > > +long_mul_is_cross_half (tree h, tree op0, tree op1) > > +{ > > + tree scratch[LONG_MUL_MAX_CAPTURES]; > > + return gimple_mul_hilo (h, scratch, NULL) > > + && long_mul_same_ops (scratch[0], scratch[1], op0, op1); > > +} > > + > > +/* Orientation of the mul_hilo capture H relative to (OP0, OP1): > > + returns 0 for high(OP0)*low(OP1), 1 for high(OP1)*low(OP0), or -1 > > + if H does not decompose that way. A cross-sum of two mul_hilos must > > + see one of each orientation -- otherwise a doubled factor would fold > > + to the wrong value. (In a self-multiply the two orientations > > + coincide; see the OP0 == OP1 bypass in long_mul_check_consistency.) > */ > > + > > +static int > > +long_mul_hilo_orientation (tree h, tree op0, tree op1) > > +{ > > + tree scratch[LONG_MUL_MAX_CAPTURES]; > > + if (!gimple_mul_hilo (h, scratch, NULL)) > > + return -1; > > + if (scratch[0] == op0 && scratch[1] == op1) > > + return 0; > > + if (scratch[0] == op1 && scratch[1] == op0) > > + return 1; > > + return -1; > > +} > > + > > +/* Find the first summand that carries operand captures, and return its > > + (op0, op1) pair in *OP0_OUT / *OP1_OUT. Returns false if no summand > > + provides them. */ > > + > > +static bool > > +long_mul_canonical_ops (const vec<long_mul_summand> &summands, > > + tree *op0_out, tree *op1_out) > > +{ > > + for (const long_mul_summand &s : summands) > > + if (s.op0) > > + { > > + *op0_out = s.op0; > > + *op1_out = s.op1; > > + return true; > > + } > > + return false; > > +} > > + > > +/* Run the cross-summand validation invariants and return the canonical > > + (op0, op1). Returns false unless all summands that carry operands > use > > + the same (op0, op1) pair (in either order), every LMX_HI/LMX_SHL_N > shift > > + equals halfwidth, every captured hilo is a true cross-half product of > > + (op0, op1), and every cross-half pair (both those inside a single > > + mul_cross_sum-bearing summand and those spread across separate > > + LMK_MUL_HILO summands) contains one of each orientation. */ > > + > > +static bool > > +long_mul_check_consistency (const vec<long_mul_summand> &summands, > > + tree *op0_out, tree *op1_out) > > +{ > > + tree op0, op1; > > + if (!long_mul_canonical_ops (summands, &op0, &op1)) > > + return false; > > + > > + tree op_type = TREE_TYPE (op0); > > + if (!INTEGRAL_TYPE_P (op_type) > > + || TYPE_PRECISION (op_type) % 2 != 0) > > + return false; > > + unsigned int halfwidth = TYPE_PRECISION (op_type) / 2; > > + > > + /* Self-multiply (x*x) collapses the two cross-halves onto one value, > > + so the complementarity constraint is a trivial no-op there. */ > > + bool need_orient = op0 != op1; > > + int mul_hilo_orient[2] = { 0, 0 }; > > + > > + for (const long_mul_summand &s : summands) > > + { > > + if (s.op0 && !long_mul_same_ops (s.op0, s.op1, op0, op1)) > > + return false; > > + if ((s.extract == LMX_HI || s.extract == LMX_SHL_N) > > + && s.shift != halfwidth) > > + return false; > > + tree hilos[3] = { s.hilo0, s.hilo1, s.hilo2 }; > > + for (tree h : hilos) > > + if (h && !long_mul_is_cross_half (h, op0, op1)) > > + return false; > > + > > + if (!need_orient) > > + continue; > > + > > + /* The two cross-sum operands are the last two non-null hilos: > > + (hilo1, hilo2) for the CARRY_*_SUM kinds, (hilo0, hilo1) for > > + the CROSS_SUM / SUM / ACCUM / LADDER_SUM kinds, none for the > > + rest. */ > > + tree a = NULL_TREE; > > + tree b = NULL_TREE; > > + if (s.hilo2) > > + { > > + a = s.hilo1; > > + b = s.hilo2; > > + } > > + else if (s.hilo1) > > + { > > + a = s.hilo0; > > + b = s.hilo1; > > + } > > + if (a && b > > + && (long_mul_hilo_orientation (a, op0, op1) > > + == long_mul_hilo_orientation (b, op0, op1))) > > + return false; > > + > > + /* Two LMK_MUL_HILO summands (the two-hilos ladder form) stand for > > + the two cross-halves separately; count orientations and require > > + the pair to be complementary. s.op0/op1 is already validated to > > + match (op0, op1) in some order above. */ > > + if (s.kind == LMK_MUL_HILO && s.op0) > > + mul_hilo_orient[s.op0 == op1]++; > > + } > > + > > + if (mul_hilo_orient[0] + mul_hilo_orient[1] >= 2 > > + && (mul_hilo_orient[0] == 0 || mul_hilo_orient[1] == 0)) > > + return false; > > + > > + *op0_out = op0; > > + *op1_out = op1; > > + return true; > > +} > > + > > +/* Compare the (already-sorted) SUMMANDS multiset against ROW.sig. */ > > + > > +static bool > > +long_mul_signature_matches (const vec<long_mul_summand> &summands, > > + const long_mul_row &row) > > +{ > > + if (row.count != summands.length ()) > > + return false; > > + for (unsigned i = 0; i < row.count; i++) > > + if (summands[i].kind != row.sig[i].kind > > + || summands[i].extract != row.sig[i].extract) > > + return false; > > + return true; > > +} > > + > > +/* Long-multiply variant table. Each row enumerates the multiset of > > + (kind, extract) summands that compose one long-multiply form. Rows > > + are sorted by long_mul_summand_compare, matching the input summands' > > + sort order, so a plain element-wise compare suffices. Rows describe > > + unsigned schoolbook expansions on an even-width 2N-bit type split at > > + half-width N; EXTRA_CHECK carries invariants the (kind, extract) > > + signature cannot express. */ > > + > > +static const long_mul_row long_mul_table[] = { > > + /* HIGH-PART fold. Notation: xh, xl, yh, yl are the half-width pieces > > + of x and y; N is the half-width. cross_sum = xh*yl + xl*yh; hilo > is > > + either xh*yl or xl*yh (consumers validate the operand shape). */ > > + /* xh*yh + (low_accum >> N) + (cross_sum >> N) > > + + ((hilo > cross_sum) << N), > > + low_accum = (xl*yl >> N) + (cross_sum & mask). */ > > + { long_mul_row::HIGH_PART, PLUS_EXPR, 4, > > + { { LMK_MUL_HIHI, LMX_NONE }, > > + { LMK_CROSS_SUM, LMX_HI }, > > + { LMK_LOW_ACCUM, LMX_HI }, > > + { LMK_CARRY_CROSS_SUM, LMX_NONE } }, > > + NULL }, > > + /* LOW-PART fold. Recover the lower 2N bits from xl*yl plus a > > + shifted cross-half term. Notation as for the HIGH-PART row > above. */ > > + /* (xl*yl & mask) | (low_accum << N), > > + low_accum = (xl*yl >> N) + (cross_sum & mask). */ > > + { long_mul_row::LOW_PART, BIT_IOR_EXPR, 2, > > + { { LMK_MUL_LOLO, LMX_LO }, > > + { LMK_LOW_ACCUM, LMX_SHL_N } }, > > + NULL }, > > +}; > > + > > +/* If a multi-used inner addition (sharing the chain's outer code) > blocked > > + linearization of a long-mul candidate, emit a dump-file hint pointing > > + at it. */ > > + > > +static void > > +long_mul_hint_shared_intermediate (gimple *shared_def) > > +{ > > + if (!shared_def || !dump_file || !(dump_flags & TDF_DETAILS)) > > + return; > > + fprintf (dump_file, "long-mul fold rejected: shared intermediate at > "); > > + print_gimple_stmt (dump_file, shared_def, 0, TDF_SLIM); > > +} > > + > > +/* Top-level entry for long-multiply folding. Walks STMT's outer > > + addition or BIT_IOR chain, classifies the summands, and dispatches > > + to create_mul_high_seq / create_mul_low_seq if the multiset matches > > + a known long-multiply form. Returns true on success. */ > > + > > +static bool > > +match_long_mul (gimple *stmt) > > +{ > > + if (!is_gimple_assign (stmt)) > > + return false; > > + tree_code outer = gimple_assign_rhs_code (stmt); > > + if (outer != PLUS_EXPR && outer != BIT_IOR_EXPR) > > + return false; > > + > > + /* Skip non-candidate adds (signed, pointer, odd-width) before > walking the > > + chain. No legitimate long-mul leaf has a type the atoms would > reject; > > + this just avoids the linearize/classify work on every other > PLUS/IOR. */ > > + tree lhs_type = TREE_TYPE (gimple_get_lhs (stmt)); > > + if (!INTEGRAL_TYPE_P (lhs_type) > > + || !TYPE_UNSIGNED (lhs_type) > > + || TYPE_PRECISION (lhs_type) % 2 != 0) > > + return false; > > + > > + auto_vec<tree, LONG_MUL_MAX_SUMMANDS + 1> leaves; > > + gimple *shared_def = NULL; > > + if (!long_mul_linearize_chain (stmt, outer, leaves, &shared_def)) > > + return false; > > + if (leaves.length () < 2) > > + return false; > > + > > + auto_vec<long_mul_summand, LONG_MUL_MAX_SUMMANDS> summands; > > + for (tree leaf : leaves) > > + { > > + long_mul_summand s; > > + if (!long_mul_classify_summand (leaf, &s)) > > + { > > + long_mul_hint_shared_intermediate (shared_def); > > + return false; > > + } > > + summands.quick_push (s); > > + } > > + summands.qsort (long_mul_summand_compare); > > + > > + /* HIGH_PART rows emit a 2N-bit multiply that is consumed by > > + pass_optimize_widening_mul (WIDEN_MULT_EXPR conversion or > > + longhand re-synthesis) or by expand (supported 2N mode); > > + LOW_PART rows emit a plain MULT_EXPR. Emission needs only a 2N > > + mode to exist in the mode table -- capability is settled on the > > + lowering side. */ > > + scalar_int_mode mode, wide_mode; > > + bool can_emit_high > > + = is_a <scalar_int_mode> (TYPE_MODE (lhs_type), &mode) > > + && GET_MODE_2XWIDER_MODE (mode).exists (&wide_mode); > > + > > + for (const long_mul_row &row : long_mul_table) > > + { > > + if (row.outer != outer > > + || (row.part == long_mul_row::HIGH_PART && !can_emit_high) > > + || !long_mul_signature_matches (summands, row)) > > + continue; > > + > > + tree op0, op1; > > + if (!long_mul_check_consistency (summands, &op0, &op1)) > > + continue; > > + > > + /* Do not emit the wide chain when an operand is subject to > > + abnormal coalescing: the widening_mul-side consumers refuse > > + such operands (see convert_mult_to_widen), which would leave > > + the chain without a consumer. */ > > + if (row.part == long_mul_row::HIGH_PART > > + && ((TREE_CODE (op0) == SSA_NAME > > + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)) > > + || (TREE_CODE (op1) == SSA_NAME > > + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1)))) > > + continue; > > + > > + if (row.extra_check && !row.extra_check (summands, stmt)) > > + continue; > > + > > + if (row.part == long_mul_row::HIGH_PART) > > + { > > + create_mul_high_seq (op0, op1, stmt); > > + if (dump_file && (dump_flags & TDF_DETAILS)) > > + fprintf (dump_file, "Long multiplication high part > folded.\n"); > > + return true; > > + } > > + create_mul_low_seq (op0, op1, stmt); > > + if (dump_file && (dump_flags & TDF_DETAILS)) > > + fprintf (dump_file, "Long multiplication low part folded.\n"); > > + return true; > > + } > > + > > + long_mul_hint_shared_intermediate (shared_def); > > + return false; > > +} > > > > /* Determine whether applying the 2 permutations (mask1 then mask2) > > gives back one of the input. */ > > @@ -5851,11 +6538,15 @@ pass_forwprop::execute (function *fun) > > } > > else if (TREE_CODE_CLASS (code) == tcc_comparison) > > changed |= forward_propagate_into_comparison > (&gsi); > > - else if ((code == PLUS_EXPR > > - || code == BIT_IOR_EXPR > > - || code == BIT_XOR_EXPR) > > - && simplify_rotate (&gsi)) > > - changed = true; > > + else if ((code == PLUS_EXPR || code == BIT_IOR_EXPR)) > > + { > > + bool folded = match_long_mul (stmt); > > + if (!folded) > > + folded = simplify_rotate (&gsi); > > + changed |= folded; > > + } > > + else if (code == BIT_XOR_EXPR) > > + changed |= simplify_rotate (&gsi); > > else if (code == VEC_PERM_EXPR) > > changed |= simplify_permutation (&gsi); > > else if (code == CONSTRUCTOR > > -- > > 2.55.0 > > >
