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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>
Subject: [PATCH v2 7/9] powerpc/bpf/32: Optimise some particular const operations
Date: Wed,  1 Feb 2023 11:04:29 +0100	[thread overview]
Message-ID: <e53b1f4a4150ec6cabcaeeef82bf9c361b5f9204.1675245773.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <4fd69ef7945518c3e27f96b95046a5c1468d35bf.1675245773.git.christophe.leroy@csgroup.eu>

Simplify multiplications and divisions with constants when the
constant is 1 or -1.

When the constant is a power of 2, replace them by bit shits.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/net/bpf_jit_comp32.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index c3bc20b91cdc..b1d6ed4d8270 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -391,7 +391,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			EMIT(PPC_RAW_MULW(dst_reg, dst_reg, src_reg));
 			break;
 		case BPF_ALU | BPF_MUL | BPF_K: /* (u32) dst *= (u32) imm */
-			if (imm >= -32768 && imm < 32768) {
+			if (imm == 1)
+				break;
+			if (imm == -1) {
+				EMIT(PPC_RAW_SUBFIC(dst_reg, dst_reg, 0));
+			} else if (is_power_of_2((u32)imm)) {
+				EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, ilog2(imm)));
+			} else if (imm >= -32768 && imm < 32768) {
 				EMIT(PPC_RAW_MULI(dst_reg, dst_reg, imm));
 			} else {
 				PPC_LI32(_R0, imm);
@@ -411,6 +417,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 				EMIT(PPC_RAW_SUBFZE(dst_reg_h, dst_reg_h));
 				break;
 			}
+			if (imm > 0 && is_power_of_2(imm)) {
+				imm = ilog2(imm);
+				EMIT(PPC_RAW_RLWINM(dst_reg_h, dst_reg_h, imm, 0, 31 - imm));
+				EMIT(PPC_RAW_RLWIMI(dst_reg_h, dst_reg, imm, 32 - imm, 31));
+				EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, imm));
+				break;
+			}
 			bpf_set_seen_register(ctx, tmp_reg);
 			PPC_LI32(tmp_reg, imm);
 			EMIT(PPC_RAW_MULW(dst_reg_h, dst_reg_h, tmp_reg));
@@ -438,8 +451,12 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			if (imm == 1)
 				break;
 
-			PPC_LI32(_R0, imm);
-			EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0));
+			if (is_power_of_2((u32)imm)) {
+				EMIT(PPC_RAW_SRWI(dst_reg, dst_reg, ilog2(imm)));
+			} else {
+				PPC_LI32(_R0, imm);
+				EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0));
+			}
 			break;
 		case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */
 			if (!imm)
-- 
2.39.1


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Hao Luo <haoluo@google.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Song Liu <song@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	linux-kernel@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Jiri Olsa <jolsa@kernel.org>,
	KP Singh <kpsingh@kernel.org>, Yonghong Song <yhs@fb.com>,
	bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2 7/9] powerpc/bpf/32: Optimise some particular const operations
Date: Wed,  1 Feb 2023 11:04:29 +0100	[thread overview]
Message-ID: <e53b1f4a4150ec6cabcaeeef82bf9c361b5f9204.1675245773.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <4fd69ef7945518c3e27f96b95046a5c1468d35bf.1675245773.git.christophe.leroy@csgroup.eu>

Simplify multiplications and divisions with constants when the
constant is 1 or -1.

When the constant is a power of 2, replace them by bit shits.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/net/bpf_jit_comp32.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index c3bc20b91cdc..b1d6ed4d8270 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -391,7 +391,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			EMIT(PPC_RAW_MULW(dst_reg, dst_reg, src_reg));
 			break;
 		case BPF_ALU | BPF_MUL | BPF_K: /* (u32) dst *= (u32) imm */
-			if (imm >= -32768 && imm < 32768) {
+			if (imm == 1)
+				break;
+			if (imm == -1) {
+				EMIT(PPC_RAW_SUBFIC(dst_reg, dst_reg, 0));
+			} else if (is_power_of_2((u32)imm)) {
+				EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, ilog2(imm)));
+			} else if (imm >= -32768 && imm < 32768) {
 				EMIT(PPC_RAW_MULI(dst_reg, dst_reg, imm));
 			} else {
 				PPC_LI32(_R0, imm);
@@ -411,6 +417,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 				EMIT(PPC_RAW_SUBFZE(dst_reg_h, dst_reg_h));
 				break;
 			}
+			if (imm > 0 && is_power_of_2(imm)) {
+				imm = ilog2(imm);
+				EMIT(PPC_RAW_RLWINM(dst_reg_h, dst_reg_h, imm, 0, 31 - imm));
+				EMIT(PPC_RAW_RLWIMI(dst_reg_h, dst_reg, imm, 32 - imm, 31));
+				EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, imm));
+				break;
+			}
 			bpf_set_seen_register(ctx, tmp_reg);
 			PPC_LI32(tmp_reg, imm);
 			EMIT(PPC_RAW_MULW(dst_reg_h, dst_reg_h, tmp_reg));
@@ -438,8 +451,12 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			if (imm == 1)
 				break;
 
-			PPC_LI32(_R0, imm);
-			EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0));
+			if (is_power_of_2((u32)imm)) {
+				EMIT(PPC_RAW_SRWI(dst_reg, dst_reg, ilog2(imm)));
+			} else {
+				PPC_LI32(_R0, imm);
+				EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0));
+			}
 			break;
 		case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */
 			if (!imm)
-- 
2.39.1


  parent reply	other threads:[~2023-02-01 10:05 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-01 10:04 [PATCH v2 1/9] powerpc: Remove __kernel_text_address() in show_instructions() Christophe Leroy
2023-02-01 10:04 ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 2/9] powerpc/bpf/32: No need to zeroise r4 when not doing tail call Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 3/9] powerpc/bpf/32: Only set a stack frame when necessary Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 4/9] powerpc/bpf/32: BPF prog is never called with more than one arg Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 5/9] powerpc/bpf: Perform complete extra passes to update addresses Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 6/9] powerpc/bpf: Only pad length-variable code at initial pass Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` Christophe Leroy [this message]
2023-02-01 10:04   ` [PATCH v2 7/9] powerpc/bpf/32: Optimise some particular const operations Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 8/9] powerpc/bpf/32: introduce a second source register for ALU operations Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-01 10:04 ` [PATCH v2 9/9] powerpc/bpf/32: perform three operands " Christophe Leroy
2023-02-01 10:04   ` Christophe Leroy
2023-02-15 12:40 ` [PATCH v2 1/9] powerpc: Remove __kernel_text_address() in show_instructions() Michael Ellerman
2023-02-15 12:40   ` Michael Ellerman

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