linux-kernel - [PATCH v3 11/18] perf llvm: Disassemble cleanup

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Message-Id: <20250122174308.350350-12-irogers@google.com>
Date: Wed, 22 Jan 2025 09:43:01 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Aditya Gupta <adityag@...ux.ibm.com>, 
	"Steinar H. Gunderson" <sesse@...gle.com>, Charlie Jenkins <charlie@...osinc.com>, 
	Changbin Du <changbin.du@...wei.com>, "Masami Hiramatsu (Google)" <mhiramat@...nel.org>, 
	James Clark <james.clark@...aro.org>, Kajol Jain <kjain@...ux.ibm.com>, 
	Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, Li Huafei <lihuafei1@...wei.com>, 
	Dmitry Vyukov <dvyukov@...gle.com>, Andi Kleen <ak@...ux.intel.com>, 
	Chaitanya S Prakash <chaitanyas.prakash@....com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, llvm@...ts.linux.dev, 
	Song Liu <song@...nel.org>, bpf@...r.kernel.org
Subject: [PATCH v3 11/18] perf llvm: Disassemble cleanup

Move the 3 LLVM initialization routines to be called in a single
init_llvm function that has its own bool to avoid repeated
initialization. Reduce the scope of triplet and avoid copying strings
for x86.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/llvm.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/llvm.c b/tools/perf/util/llvm.c
index a0774373f0d6..a28f130c8951 100644
--- a/tools/perf/util/llvm.c
+++ b/tools/perf/util/llvm.c
@@ -244,6 +244,17 @@ static void perf_LLVMDisasmDispose(LLVMDisasmContextRef context)
 #endif
 }
 
+static void init_llvm(void)
+{
+	static bool init;
+
+	if (!init) {
+		perf_LLVMInitializeAllTargetInfos();
+		perf_LLVMInitializeAllTargetMCs();
+		perf_LLVMInitializeAllDisassemblers();
+		init = true;
+	}
+}
 
 static void free_llvm_inline_frames(struct llvm_a2l_frame *inline_frames,
 				    int num_frames)
@@ -339,7 +350,6 @@ int symbol__disassemble_llvm(const char *filename, struct symbol *sym,
 	u64 buf_len;
 	u64 pc;
 	bool is_64bit;
-	char triplet[64];
 	char disasm_buf[2048];
 	size_t disasm_len;
 	struct disasm_line *dl;
@@ -352,27 +362,25 @@ int symbol__disassemble_llvm(const char *filename, struct symbol *sym,
 	if (args->options->objdump_path)
 		return -1;
 
-	perf_LLVMInitializeAllTargetInfos();
-	perf_LLVMInitializeAllTargetMCs();
-	perf_LLVMInitializeAllDisassemblers();
-
 	buf = dso__read_symbol(dso, filename, map, sym,
 			       &code_buf, &buf_len, &is_64bit);
 	if (buf == NULL)
 		return -1;
 
+	init_llvm();
 	if (arch__is(args->arch, "x86")) {
-		if (is_64bit)
-			scnprintf(triplet, sizeof(triplet), "x86_64-pc-linux");
-		else
-			scnprintf(triplet, sizeof(triplet), "i686-pc-linux");
+		const char *triplet = is_64bit ? "x86_64-pc-linux" : "i686-pc-linux";
+
+		disasm = perf_LLVMCreateDisasm(triplet, &storage, /*tag_type=*/0,
+					       /*get_op_info=*/NULL, symbol_lookup_callback);
 	} else {
+		char triplet[64];
+
 		scnprintf(triplet, sizeof(triplet), "%s-linux-gnu",
 			  args->arch->name);
+		disasm = perf_LLVMCreateDisasm(triplet, &storage, /*tag_type=*/0,
+					       /*get_op_info=*/NULL, symbol_lookup_callback);
 	}
-
-	disasm = perf_LLVMCreateDisasm(triplet, &storage, 0, NULL,
-				       symbol_lookup_callback);
 	if (disasm == NULL)
 		goto err;
 
-- 
2.48.1.262.g85cc9f2d1e-goog