The current checkstack.pl script has a few problems, stemming from the
overly simplistic attempt at parsing objdump output with regular
expresions: For example, on x86_64 it doesn't take the push
instruction into account, making it consistently underestimate the
real stack use, and it also doesn't capture stack pointer adjustments
of exactly 128 bytes [1].
Since newer gcc (>= 4.6) knows about -fstack-usage, we might as well
take the information straight from the horse's mouth. This patch
introduces scripts/stackusage, which is a simple wrapper for running
make with KCFLAGS set to -fstack-usage. Example use is
scripts/stackusage -o out.su -j8 lib/
The script understands "-o foo" for writing to 'foo' and -h for a
trivial help text; anything else is passed to make.
Afterwards, we find all newly created .su files, massage them a
little, sort by stack use and write the result to a single output
file.
Note that the function names printed by (at least) gcc 4.7 are
sometimes useless. For example, the first three lines of out.su
generated above are
./lib/decompress_bunzip2.c:155 get_next_block 448 static
./lib/decompress_unlzma.c:537 unlzma 336 static
./lib/vsprintf.c:616 8 304 static
That function '8' is really the static symbol_string(), but it has
been subject to 'interprocedural scalar replacement of aggregates', so
its name in the object file is 'symbol_string.isra.8'. gcc 5.0 doesn't
have this problem; it uses the full name as seen in the object file.
[1] Since gcc encodes that by
48 83 c4 80 add $0xffffffffffffff80,%rsp
and not
48 81 ec 80 00 00 00 sub $0x80,%rsp
since -128 fits in an imm8.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
scripts/stackusage | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
create mode 100755 scripts/stackusage
diff --git a/scripts/stackusage b/scripts/stackusage
new file mode 100755
index 000000000000..b30dfa6b3a0a
--- /dev/null
+++ b/scripts/stackusage
@@ -0,0 +1,33 @@
+#!/bin/sh
+
+outfile=""
+now=`date +%s`
+
+while [ $# -gt 0 ]
+do
+ case "$1" in
+ -o)
+ outfile="$2"
+ shift 2;;
+ -h)
+ echo "usage: $0 [-o outfile] <make options/args>"
+ exit 0;;
+ *) break;;
+ esac
+done
+
+if [ -z "$outfile" ]
+then
+ outfile=`mktemp --tmpdir stackusage.$$.XXXX`
+fi
+
+KCFLAGS="${KCFLAGS} -fstack-usage" make "$@"
+
+# Prepend directory name to file names, remove column information,
+# make file:column/function/size/type properly tab-separated.
+find . -name '*.su' -newermt "@${now}" -print | \
+ xargs perl -MFile::Basename -pe \
+ '$d = dirname($ARGV); s#([^:]+:[0-9]+):[0-9]+:#$d/$1\t#;' | \
+ sort -k3,3nr > "${outfile}"
+
+echo "$0: output written to ${outfile}"
--
2.1.3
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