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From: Philipp Tomsich <ptomsich@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-4104] RISC-V: Split "(a & (1UL << bitno)) ? 0 : -1" to bext + addi Date: Wed, 16 Nov 2022 20:01:01 +0000 (GMT) [thread overview] Message-ID: <20221116200101.985D5382FAEC@sourceware.org> (raw) https://gcc.gnu.org/g:32462550f2803aafb726b5ae20d4d95ce36dcd9c commit r13-4104-g32462550f2803aafb726b5ae20d4d95ce36dcd9c Author: Philipp Tomsich <philipp.tomsich@vrull.eu> Date: Wed May 11 13:50:11 2022 +0200 RISC-V: Split "(a & (1UL << bitno)) ? 0 : -1" to bext + addi For a straightforward application of bext for the following function long bext64(long a, char bitno) { return (a & (1UL << bitno)) ? 0 : -1; } we generate srl a0,a0,a1 # 7 [c=4 l=4] lshrdi3 andi a0,a0,1 # 8 [c=4 l=4] anddi3/1 addi a0,a0,-1 # 14 [c=4 l=4] adddi3/1 due to the following failed match at combine time: (set (reg:DI 82) (zero_extract:DI (reg:DI 83) (const_int 1 [0x1]) (reg:DI 84))) The existing pattern for bext requires the 3rd argument to zero_extract to be a QImode register wrapped in a zero_extension. This adds an additional pattern that allows an Xmode argument. With this change, the testcase compiles to bext a0,a0,a1 # 8 [c=4 l=4] *bextdi addi a0,a0,-1 # 14 [c=4 l=4] adddi3/1 gcc/ChangeLog: * config/riscv/bitmanip.md (*bext<mode>): Add an additional pattern that allows the 3rd argument to zero_extract to be an Xmode register operand. gcc/testsuite/ChangeLog: * gcc.target/riscv/zbs-bext.c: Add testcases. * gcc.target/riscv/zbs-bexti.c: Add testcases. Diff: --- gcc/config/riscv/bitmanip.md | 12 ++++++++++++ gcc/testsuite/gcc.target/riscv/zbs-bext.c | 23 ++++++++++++++++++++--- gcc/testsuite/gcc.target/riscv/zbs-bexti.c | 25 +++++++++++++++++++++++++ 3 files changed, 57 insertions(+), 3 deletions(-) diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md index 48c249f2a68..86cc85001c3 100644 --- a/gcc/config/riscv/bitmanip.md +++ b/gcc/config/riscv/bitmanip.md @@ -394,6 +394,18 @@ "bext\t%0,%1,%2" [(set_attr "type" "bitmanip")]) +;; When performing `(a & (1UL << bitno)) ? 0 : -1` the combiner +;; usually has the `bitno` typed as X-mode (i.e. no further +;; zero-extension is performed around the bitno). +(define_insn "*bext<mode>" + [(set (match_operand:X 0 "register_operand" "=r") + (zero_extract:X (match_operand:X 1 "register_operand" "r") + (const_int 1) + (match_operand:X 2 "register_operand" "r")))] + "TARGET_ZBS" + "bext\t%0,%1,%2" + [(set_attr "type" "bitmanip")]) + (define_insn "*bexti" [(set (match_operand:X 0 "register_operand" "=r") (zero_extract:X (match_operand:X 1 "register_operand" "r") diff --git a/gcc/testsuite/gcc.target/riscv/zbs-bext.c b/gcc/testsuite/gcc.target/riscv/zbs-bext.c index 47982396119..8de9c5a167c 100644 --- a/gcc/testsuite/gcc.target/riscv/zbs-bext.c +++ b/gcc/testsuite/gcc.target/riscv/zbs-bext.c @@ -1,6 +1,6 @@ /* { dg-do compile } */ /* { dg-options "-march=rv64gc_zbs -mabi=lp64" } */ -/* { dg-skip-if "" { *-*-* } { "-O0" } } */ +/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" } } */ /* bext */ long @@ -16,6 +16,23 @@ foo1 (long i) return 1L & (i >> 20); } +long bext64_1(long a, char bitno) +{ + return (a & (1UL << bitno)) ? 1 : 0; +} + +long bext64_2(long a, char bitno) +{ + return (a & (1UL << bitno)) ? 0 : -1; +} + +long bext64_3(long a, char bitno) +{ + return (a & (1UL << bitno)) ? -1 : 0; +} + /* { dg-final { scan-assembler-times "bexti\t" 1 } } */ -/* { dg-final { scan-assembler-times "bext\t" 1 } } */ -/* { dg-final { scan-assembler-not "andi" } } */ +/* { dg-final { scan-assembler-times "bext\t" 4 } } */ +/* { dg-final { scan-assembler-times "addi\t" 1 } } */ +/* { dg-final { scan-assembler-times "neg\t" 1 } } */ +/* { dg-final { scan-assembler-not "andi" } } */ \ No newline at end of file diff --git a/gcc/testsuite/gcc.target/riscv/zbs-bexti.c b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c new file mode 100644 index 00000000000..30b69c9bc3e --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/zbs-bexti.c @@ -0,0 +1,25 @@ +/* { dg-do compile } */ +/* { dg-options "-march=rv64gc_zbs -mabi=lp64" } */ +/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" } } */ + +/* bexti */ +#define BIT_NO 21 + +long bexti64_1(long a, char bitno) +{ + return (a & (1UL << BIT_NO)) ? 1 : 0; +} + +long bexti64_2(long a, char bitno) +{ + return (a & (1UL << BIT_NO)) ? 0 : -1; +} + +long bexti64_3(long a, char bitno) +{ + return (a & (1UL << BIT_NO)) ? -1 : 0; +} + +/* { dg-final { scan-assembler-times "bexti\t" 3 } } */ +/* { dg-final { scan-assembler-times "addi\t" 1 } } */ +/* { dg-final { scan-assembler-times "neg\t" 1 } } */
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