From 69315e4ea7f5455bc1bc2633e2eb37805ad629b4 Mon Sep 17 00:00:00 2001
From: David Srbecky <dsrbecky@google.com>
Date: Thu, 29 Apr 2021 21:06:47 +0100
Subject: [PATCH] Use create_minidebuginfo tool instead of bash script.

The behaviour is semantically identical, however,
the tool additionally sorts the symbols by address,
compresses frame unwind information more efficiently,
and improves random-accessibility for lazy decompression.

Overall, the changes balance and the output size is same,
however, libunwindstack can access the data much faster
while using less memory (due to the lazy decompression).
It will also enable further improvements in the future.

Bug: 110133331
Test: ART unwinding tests, run prefetto on the device.
Change-Id: Id48f9fe67fb67fcf2b90cc3b217b71bb8f5147ca
---
 cc/builder.go    | 17 ++++++++++++-----
 cc/makevars.go   |  1 +
 scripts/strip.sh | 28 +++++++++++++++++++++++++++-
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/cc/builder.go b/cc/builder.go
index ad7e1e6ac..054201567 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -126,15 +126,22 @@ var (
 
 	_ = pctx.SourcePathVariable("stripPath", "build/soong/scripts/strip.sh")
 	_ = pctx.SourcePathVariable("xzCmd", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/xz")
+	_ = pctx.SourcePathVariable("createMiniDebugInfo", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/create_minidebuginfo")
 
 	// Rule to invoke `strip` (to discard symbols and data from object files).
 	strip = pctx.AndroidStaticRule("strip",
 		blueprint.RuleParams{
-			Depfile:     "${out}.d",
-			Deps:        blueprint.DepsGCC,
-			Command:     "XZ=$xzCmd CLANG_BIN=${config.ClangBin} $stripPath ${args} -i ${in} -o ${out} -d ${out}.d",
-			CommandDeps: []string{"$stripPath", "$xzCmd"},
-			Pool:        darwinStripPool,
+			Depfile: "${out}.d",
+			Deps:    blueprint.DepsGCC,
+			Command: "XZ=$xzCmd CREATE_MINIDEBUGINFO=$createMiniDebugInfo CLANG_BIN=${config.ClangBin} $stripPath ${args} -i ${in} -o ${out} -d ${out}.d",
+			CommandDeps: func() []string {
+				if runtime.GOOS != "darwin" {
+					return []string{"$stripPath", "$xzCmd", "$createMiniDebugInfo"}
+				} else {
+					return []string{"$stripPath", "$xzCmd"}
+				}
+			}(),
+			Pool: darwinStripPool,
 		},
 		"args", "crossCompile")
 
diff --git a/cc/makevars.go b/cc/makevars.go
index fa0b2ccce..2b7bb9bb6 100644
--- a/cc/makevars.go
+++ b/cc/makevars.go
@@ -151,6 +151,7 @@ func makeVarsProvider(ctx android.MakeVarsContext) {
 
 	ctx.Strict("SOONG_STRIP_PATH", "${stripPath}")
 	ctx.Strict("XZ", "${xzCmd}")
+	ctx.Strict("CREATE_MINIDEBUGINFO", "${createMiniDebugInfo}")
 
 	includeFlags, err := ctx.Eval("${config.CommonGlobalIncludes}")
 	if err != nil {
diff --git a/scripts/strip.sh b/scripts/strip.sh
index e3e527381..d09c187b1 100755
--- a/scripts/strip.sh
+++ b/scripts/strip.sh
@@ -71,7 +71,7 @@ do_strip_keep_symbol_list() {
     "${CLANG_BIN}/llvm-objcopy" -w "${infile}" "${outfile}.tmp" ${KEEP_SYMBOLS}
 }
 
-do_strip_keep_mini_debug_info() {
+do_strip_keep_mini_debug_info_darwin() {
     rm -f "${outfile}.dynsyms" "${outfile}.funcsyms" "${outfile}.keep_symbols" "${outfile}.debug" "${outfile}.mini_debuginfo" "${outfile}.mini_debuginfo.xz"
     local fail=
     "${CLANG_BIN}/llvm-strip" --strip-all --keep-section=.ARM.attributes --remove-section=.comment "${infile}" -o "${outfile}.tmp" || fail=true
@@ -92,6 +92,32 @@ do_strip_keep_mini_debug_info() {
     fi
 }
 
+do_strip_keep_mini_debug_info_linux() {
+    rm -f "${outfile}.mini_debuginfo.xz"
+    local fail=
+    "${CLANG_BIN}/llvm-strip" --strip-all --keep-section=.ARM.attributes --remove-section=.comment "${infile}" -o "${outfile}.tmp" || fail=true
+
+    if [ -z $fail ]; then
+        "${CREATE_MINIDEBUGINFO}" "${infile}" "${outfile}.mini_debuginfo.xz"
+        "${CLANG_BIN}/llvm-objcopy" --add-section .gnu_debugdata="${outfile}.mini_debuginfo.xz" "${outfile}.tmp"
+        rm -f "${outfile}.mini_debuginfo.xz"
+    else
+        cp -f "${infile}" "${outfile}.tmp"
+    fi
+}
+
+do_strip_keep_mini_debug_info() {
+  case $(uname) in
+      Linux)
+          do_strip_keep_mini_debug_info_linux
+          ;;
+      Darwin)
+          do_strip_keep_mini_debug_info_darwin
+          ;;
+      *) echo "unknown OS:" $(uname) >&2 && exit 1;;
+  esac
+}
+
 do_add_gnu_debuglink() {
     "${CLANG_BIN}/llvm-objcopy" --add-gnu-debuglink="${infile}" "${outfile}.tmp"
 }