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From: Roger Sayle <sayle@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-4473] bfin: Popcount-related improvements to machine description. Date: Mon, 18 Oct 2021 11:00:23 +0000 (GMT) [thread overview] Message-ID: <20211018110023.247EA3858404@sourceware.org> (raw) https://gcc.gnu.org/g:fecda57e60488d15a180b8dde02cf7a4d978ebc7 commit r12-4473-gfecda57e60488d15a180b8dde02cf7a4d978ebc7 Author: Roger Sayle <roger@nextmovesoftware.com> Date: Mon Oct 18 11:56:56 2021 +0100 bfin: Popcount-related improvements to machine description. Blackfin processors support a ONES instruction that implements a 32-bit popcount returning a 16-bit result. This instruction was previously described by GCC's bfin backend using an UNSPEC, which this patch changes to use a popcount:SI rtx thats capture its semantics, allowing it to evaluated and simplified at compile-time. I've decided to keep the instruction name the same (avoiding any changes to the __builtin_bfin_ones machinery), but have provided popcountsi2 and popcounthi2 expanders so that the middle-end can use this instruction to implement __builtin_popcount (and __builtin_parity). The new testcase ones.c short foo () { int t = 5; short r = __builtin_bfin_ones(t); return r; } previously generated: _foo: nop; nop; R0 = 5 (X); R0.L = ONES R0; rts; with this patch, now generates: _foo: nop; nop; nop; R0 = 2 (X); rts; The new testcase popcount.c int foo(int x) { return __builtin_popcount(x); } previously generated: _foo: [--SP] = RETS; SP += -12; call ___popcountsi2; SP += 12; RETS = [SP++]; rts; now generates: _foo: nop; nop; R0.L = ONES R0; R0 = R0.L (Z); rts; And the new testcase parity.c int foo(int x) { return __builtin_parity(x); } previously generated: _foo: [--SP] = RETS; SP += -12; call ___paritysi2; SP += 12; RETS = [SP++]; rts; now generates: _foo: nop; R1 = 1 (X); R0.L = ONES R0; R0 = R1 & R0; rts; 2021-10-18 Roger Sayle <roger@nextmovesoftware.com> gcc/ChangeLog * config/bfin/bfin.md (define_constants): Remove UNSPEC_ONES. (define_insn "ones"): Replace UNSPEC_ONES with a truncate of a popcount, allowing compile-time evaluation/simplification. (popcountsi2, popcounthi2): New expanders using a "ones" insn. gcc/testsuite/ChangeLog * gcc.target/bfin/ones.c: New test case. * gcc.target/bfin/parity.c: New test case. * gcc.target/bfin/popcount.c: New test case. Diff: --- gcc/config/bfin/bfin.md | 27 +++++++++++++++++++++++---- gcc/testsuite/gcc.target/bfin/ones.c | 11 +++++++++++ gcc/testsuite/gcc.target/bfin/parity.c | 9 +++++++++ gcc/testsuite/gcc.target/bfin/popcount.c | 9 +++++++++ 4 files changed, 52 insertions(+), 4 deletions(-) diff --git a/gcc/config/bfin/bfin.md b/gcc/config/bfin/bfin.md index 1ec0bbbd2d9..8b311f3ab11 100644 --- a/gcc/config/bfin/bfin.md +++ b/gcc/config/bfin/bfin.md @@ -138,8 +138,7 @@ ;; Distinguish a 32-bit version of an insn from a 16-bit version. (UNSPEC_32BIT 11) (UNSPEC_NOP 12) - (UNSPEC_ONES 13) - (UNSPEC_ATOMIC 14)]) + (UNSPEC_ATOMIC 13)]) (define_constants [(UNSPEC_VOLATILE_CSYNC 1) @@ -1398,12 +1397,32 @@ (define_insn "ones" [(set (match_operand:HI 0 "register_operand" "=d") - (unspec:HI [(match_operand:SI 1 "register_operand" "d")] - UNSPEC_ONES))] + (truncate:HI + (popcount:SI (match_operand:SI 1 "register_operand" "d"))))] "" "%h0 = ONES %1;" [(set_attr "type" "alu0")]) +(define_expand "popcountsi2" + [(set (match_dup 2) + (truncate:HI (popcount:SI (match_operand:SI 1 "register_operand" "")))) + (set (match_operand:SI 0 "register_operand") + (zero_extend:SI (match_dup 2)))] + "" +{ + operands[2] = gen_reg_rtx (HImode); +}) + +(define_expand "popcounthi2" + [(set (match_dup 2) + (zero_extend:SI (match_operand:HI 1 "register_operand" ""))) + (set (match_operand:HI 0 "register_operand") + (truncate:HI (popcount:SI (match_dup 2))))] + "" +{ + operands[2] = gen_reg_rtx (SImode); +}) + (define_insn "smaxsi3" [(set (match_operand:SI 0 "register_operand" "=d") (smax:SI (match_operand:SI 1 "register_operand" "d") diff --git a/gcc/testsuite/gcc.target/bfin/ones.c b/gcc/testsuite/gcc.target/bfin/ones.c new file mode 100644 index 00000000000..cdffe845c4d --- /dev/null +++ b/gcc/testsuite/gcc.target/bfin/ones.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +short foo () +{ + int t = 5; + short r = __builtin_bfin_ones(t); + return r; +} + +/* { dg-final { scan-assembler-not "ONES" } } */ diff --git a/gcc/testsuite/gcc.target/bfin/parity.c b/gcc/testsuite/gcc.target/bfin/parity.c new file mode 100644 index 00000000000..6490b7fce02 --- /dev/null +++ b/gcc/testsuite/gcc.target/bfin/parity.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +int foo(int x) +{ + return __builtin_parity(x); +} + +/* { dg-final { scan-assembler "ONES" } } */ diff --git a/gcc/testsuite/gcc.target/bfin/popcount.c b/gcc/testsuite/gcc.target/bfin/popcount.c new file mode 100644 index 00000000000..51c19bee0c9 --- /dev/null +++ b/gcc/testsuite/gcc.target/bfin/popcount.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +int foo(int x) +{ + return __builtin_popcount(x); +} + +/* { dg-final { scan-assembler "ONES" } } */
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