From: Philipp Tomsich <philipp.tomsich@vrull.eu>
To: gcc-patches@gcc.gnu.org
Cc: Christoph Muellner <christoph.muellner@vrull.eu>,
Palmer Dabbelt <palmer@rivosinc.com>,
Kito Cheng <kito.cheng@gmail.com>,
Vineet Gupta <vineetg@rivosinc.com>,
Jeff Law <jlaw@ventanamicro.com>,
Philipp Tomsich <philipp.tomsich@vrull.eu>
Subject: [PATCH] RISC-V: Optimize slli(.uw)? + addw + zext.w into sh[123]add + zext.w
Date: Tue, 8 Nov 2022 20:57:30 +0100 [thread overview]
Message-ID: <20221108195730.2701496-1-philipp.tomsich@vrull.eu> (raw)
gcc/ChangeLog:
* config/riscv/bitmanip.md: Handle corner-cases for combine
when chaining slli(.uw)? + addw
gcc/testsuite/ChangeLog:
* gcc.target/riscv/zba-shNadd-04.c: New test.
---
gcc/config/riscv/bitmanip.md | 49 +++++++++++++++++++
gcc/config/riscv/riscv-protos.h | 1 +
gcc/config/riscv/riscv.cc | 7 +++
.../gcc.target/riscv/zba-shNadd-04.c | 23 +++++++++
4 files changed, 80 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/riscv/zba-shNadd-04.c
diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md
index 726a07b0d90..cbc00455b67 100644
--- a/gcc/config/riscv/bitmanip.md
+++ b/gcc/config/riscv/bitmanip.md
@@ -56,6 +56,55 @@
[(set (match_dup 5) (plus:DI (ashift:DI (match_dup 1) (match_dup 2)) (match_dup 3)))
(set (match_dup 0) (sign_extend:DI (div:SI (subreg:SI (match_dup 5) 0) (subreg:SI (match_dup 4) 0))))])
+; Zba does not provide W-forms of sh[123]add(.uw)?, which leads to an
+; interesting irregularity: we can generate a signed 32-bit result
+; using slli(.uw)?+ addw, but a unsigned 32-bit result can be more
+; efficiently be generated as sh[123]add+zext.w (the .uw can be
+; dropped, if we zero-extend the output anyway).
+;
+; To enable this optimization, we split [ slli(.uw)?, addw, zext.w ]
+; into [ sh[123]add, zext.w ] for use during combine.
+(define_split
+ [(set (match_operand:DI 0 "register_operand")
+ (zero_extend:DI (plus:SI (ashift:SI (subreg:SI (match_operand:DI 1 "register_operand") 0)
+ (match_operand:QI 2 "imm123_operand"))
+ (subreg:SI (match_operand:DI 3 "register_operand") 0))))]
+ "TARGET_64BIT && TARGET_ZBA"
+ [(set (match_dup 0) (plus:DI (ashift:DI (match_dup 1) (match_dup 2)) (match_dup 3)))
+ (set (match_dup 0) (zero_extend:DI (subreg:SI (match_dup 0) 0)))])
+
+(define_split
+ [(set (match_operand:DI 0 "register_operand")
+ (zero_extend:DI (plus:SI (subreg:SI (and:DI (ashift:DI (match_operand:DI 1 "register_operand")
+ (match_operand:QI 2 "imm123_operand"))
+ (match_operand:DI 3 "consecutive_bits_operand")) 0)
+ (subreg:SI (match_operand:DI 4 "register_operand") 0))))]
+ "TARGET_64BIT && TARGET_ZBA
+ && riscv_shamt_matches_mask_p (INTVAL (operands[2]), INTVAL (operands[3]))"
+ [(set (match_dup 0) (plus:DI (ashift:DI (match_dup 1) (match_dup 2)) (match_dup 4)))
+ (set (match_dup 0) (zero_extend:DI (subreg:SI (match_dup 0) 0)))])
+
+; Make sure that an andi followed by a sh[123]add remains a two instruction
+; sequence--and is not torn apart into slli, slri, add.
+(define_insn_and_split "*andi_add.uw"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (plus:DI (and:DI (ashift:DI (match_operand:DI 1 "register_operand" "r")
+ (match_operand:QI 2 "imm123_operand" "Ds3"))
+ (match_operand:DI 3 "consecutive_bits_operand" ""))
+ (match_operand:DI 4 "register_operand" "r")))
+ (clobber (match_scratch:DI 5 "=&r"))]
+ "TARGET_64BIT && TARGET_ZBA
+ && riscv_shamt_matches_mask_p (INTVAL (operands[2]), INTVAL (operands[3]))
+ && SMALL_OPERAND (INTVAL (operands[3]) >> INTVAL (operands[2]))"
+ "#"
+ "&& reload_completed"
+ [(set (match_dup 5) (and:DI (match_dup 1) (match_dup 3)))
+ (set (match_dup 0) (plus:DI (ashift:DI (match_dup 5) (match_dup 2))
+ (match_dup 4)))]
+{
+ operands[3] = GEN_INT (INTVAL (operands[3]) >> INTVAL (operands[2]));
+})
+
(define_insn "*shNadduw"
[(set (match_operand:DI 0 "register_operand" "=r")
(plus:DI
diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index 5a718bb62b4..2ec3af05aa4 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -77,6 +77,7 @@ extern bool riscv_gpr_save_operation_p (rtx);
extern void riscv_reinit (void);
extern poly_uint64 riscv_regmode_natural_size (machine_mode);
extern bool riscv_v_ext_vector_mode_p (machine_mode);
+extern bool riscv_shamt_matches_mask_p (int, HOST_WIDE_INT);
/* Routines implemented in riscv-c.cc. */
void riscv_cpu_cpp_builtins (cpp_reader *);
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 0b2c4b3599d..5a632058003 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -6497,6 +6497,13 @@ riscv_regmode_natural_size (machine_mode mode)
return UNITS_PER_WORD;
}
+/* Return true if a shift-amount matches the trailing cleared bits on a bitmask */
+bool
+riscv_shamt_matches_mask_p (int shamt, HOST_WIDE_INT mask)
+{
+ return shamt == ctz_hwi (mask);
+}
+
/* Initialize the GCC target structure. */
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
diff --git a/gcc/testsuite/gcc.target/riscv/zba-shNadd-04.c b/gcc/testsuite/gcc.target/riscv/zba-shNadd-04.c
new file mode 100644
index 00000000000..abed1491039
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/zba-shNadd-04.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zba -mabi=lp64" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" } } */
+
+long long sub1(unsigned long long a, unsigned long long b)
+{
+ b = (b << 32) >> 31;
+ unsigned int x = a + b;
+ return x;
+}
+
+long long sub2(unsigned long long a, unsigned long long b)
+{
+ return (unsigned int)(a + (b << 1));
+}
+
+long long sub3(unsigned long long a, unsigned long long b)
+{
+ return (a + (b << 1)) & ~0u;
+}
+
+/* { dg-final { scan-assembler-times "sh1add" 3 } } */
+/* { dg-final { scan-assembler-times "zext.w\t" 3 } } */
--
2.34.1
next reply other threads:[~2022-11-08 19:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 19:57 Philipp Tomsich [this message]
2022-11-18 19:52 ` Jeff Law
2022-11-18 19:57 ` Philipp Tomsich
2022-11-18 19:59 ` Philipp Tomsich
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