From acbb5ef06ee97849ecd5412ab56c1dff0f0d2fcf Mon Sep 17 00:00:00 2001 From: Philipp Tomsich Date: Tue, 11 Oct 2022 15:50:11 +0200 Subject: [PATCH] RISC-V: Optimize branches testing a bit-range or a shifted immediate gcc/ChangeLog: * config/riscv/predicates.md (shifted_const_arith_operand): New predicate. (uimm_extra_bit_operand): New predicate. * config/riscv/riscv.md (*branch_shiftedarith_equals_zero): New pattern. (*branch_shiftedmask_equals_zero): New pattern. gcc/testsuite/ChangeLog: * gcc.target/riscv/branch-1.c: New test. --- gcc/config/riscv/predicates.md | 23 ++++++++++++++ gcc/config/riscv/riscv.md | 51 +++++++++++++++++++++++++++++++ gcc/testsuite/gcc.target/riscv/branch-1.c | 37 ++++++++++++++++++++++ 3 files changed, 111 insertions(+) create mode 100644 gcc/testsuite/gcc.target/riscv/branch-1.c diff --git a/gcc/config/riscv/predicates.md b/gcc/config/riscv/predicates.md index ffb3fca..d5c097e 100644 --- a/gcc/config/riscv/predicates.md +++ b/gcc/config/riscv/predicates.md @@ -290,3 +290,26 @@ (define_predicate "const_nottwobits_operand" (and (match_code "const_int") (match_test "popcount_hwi (~UINTVAL (op)) == 2"))) + +;; A CONST_INT operand that consists of a single run of 32 consecutive +;; set bits. +(define_predicate "consecutive_bits32_operand" + (and (match_operand 0 "consecutive_bits_operand") + (match_test "popcount_hwi (UINTVAL (op)) == 32"))) + +;; A CONST_INT operand that, if shifted down to start with its least +;; significant non-zero bit, is a SMALL_OPERAND (suitable as an +;; immediate to logical and arithmetic instructions). +(define_predicate "shifted_const_arith_operand" + (and (match_code "const_int") + (match_test "ctz_hwi (INTVAL (op)) > 0") + (match_test "SMALL_OPERAND (INTVAL (op) >> ctz_hwi (INTVAL (op)))"))) + +;; A CONST_INT operand that fits into the unsigned half of a +;; signed-immediate after the top bit has been cleared. +(define_predicate "uimm_extra_bit_operand" + (and (match_code "const_int") + (not (and (match_test "SMALL_OPERAND (INTVAL (op))") + (match_test "INTVAL (op) > 0"))) + (ior (match_test "SMALL_OPERAND (UINTVAL (op) & ~(HOST_WIDE_INT_1U << floor_log2 (UINTVAL (op))))") + (match_test "popcount_hwi (UINTVAL (op)) == 2")))) diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md index 0469882..b7bb338 100644 --- a/gcc/config/riscv/riscv.md +++ b/gcc/config/riscv/riscv.md @@ -2216,6 +2216,57 @@ ;; Conditional branches +(define_insn_and_split "*branch_shiftedarith_equals_zero" + [(set (pc) + (if_then_else (match_operator 1 "equality_operator" + [(and:ANYI (match_operand:ANYI 2 "register_operand" "r") + (match_operand 3 "shifted_const_arith_operand" "i")) + (const_int 0)]) + (label_ref (match_operand 0 "" "")) + (pc))) + (clobber (match_scratch:ANYI 4 "=&r"))] + "INTVAL (operands[3]) >= 0 || !partial_subreg_p (operands[2])" + "#" + "&& reload_completed" + [(set (match_dup 4) (lshiftrt:ANYI (match_dup 2) (match_dup 6))) + (set (match_dup 4) (and:ANYI (match_dup 4) (match_dup 7))) + (set (pc) (if_then_else (match_op_dup 1 [(match_dup 4) (const_int 0)]) + (label_ref (match_dup 0)) (pc)))] +{ + HOST_WIDE_INT mask = INTVAL (operands[3]); + int trailing = ctz_hwi (mask); + + operands[6] = GEN_INT (trailing); + operands[7] = GEN_INT (mask >> trailing); +}) + +(define_insn_and_split "*branch_shiftedmask_equals_zero" + [(set (pc) + (if_then_else (match_operator 1 "equality_operator" + [(and:ANYI (match_operand:ANYI 2 "register_operand" "r") + (match_operand 3 "consecutive_bits_operand" "i")) + (const_int 0)]) + (label_ref (match_operand 0 "" "")) + (pc))) + (clobber (match_scratch:X 4 "=&r"))] + "(INTVAL (operands[3]) >= 0 || !partial_subreg_p (operands[2])) + && popcount_hwi (INTVAL (operands[3])) > 1 + && !SMALL_OPERAND (INTVAL (operands[3]))" + "#" + "&& reload_completed" + [(set (match_dup 4) (ashift:X (subreg:X (match_dup 2) 0) (match_dup 6))) + (set (match_dup 4) (lshiftrt:X (match_dup 4) (match_dup 7))) + (set (pc) (if_then_else (match_op_dup 1 [(match_dup 4) (const_int 0)]) + (label_ref (match_dup 0)) (pc)))] +{ + unsigned HOST_WIDE_INT mask = INTVAL (operands[3]); + int leading = clz_hwi (mask); + int trailing = ctz_hwi (mask); + + operands[6] = GEN_INT (leading); + operands[7] = GEN_INT (leading + trailing); +}) + (define_insn "*branch" [(set (pc) (if_then_else diff --git a/gcc/testsuite/gcc.target/riscv/branch-1.c b/gcc/testsuite/gcc.target/riscv/branch-1.c new file mode 100644 index 0000000..b4a3a94 --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/branch-1.c @@ -0,0 +1,37 @@ +/* { dg-do compile } */ +/* { dg-options "-march=rv64gc -mabi=lp64" } */ +/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-O1" } } */ + +void g(); + +void f(long long a) +{ + if (a & 0xff00) + g(); +} + +void f2(long long a) +{ + if (a & (-4ull << 3)) + g(); +} + +void f3(long long a) +{ + if (a & 0xffff00) + g(); +} + +void f4(long long a) +{ + if (a & 0x7ff800) + g(); +} + +/* { dg-final { scan-assembler-times "slli\t" 2 } } */ +/* { dg-final { scan-assembler-times "srli\t" 3 } } */ +/* { dg-final { scan-assembler-times "andi\t" 1 } } */ +/* { dg-final { scan-assembler-times "\tli\t" 1 } } */ +/* { dg-final { scan-assembler-not "addi\t" } } */ +/* { dg-final { scan-assembler-not "and\t" } } */ + -- 2.7.4