[PATCH] dim: Add --fast option to sparse

[Arkadiusz Hiler]

Running sparse on each commit in the provided range can be very time
consuming for large series.

With --fast switch we treat the whole range as a single change that gets
checked for any new sparse errors.

Cc: Jani Nikula <jani.nikula at intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
---
 dim     | 21 ++++++++++++++++++---
 dim.rst |  8 +++++---
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/dim b/dim
index 1e61fe2..5264049 100755
--- a/dim
+++ b/dim
@@ -1786,8 +1786,14 @@ function _restore_head_on_exit
 
 function dim_sparse
 {
-	local range rv sr prev_sr prev_remapped diff_result remap_log commits
+	local range rv sr prev_sr prev_remapped diff_result remap_log commits fast prev_rev
 
+    if [ "$1" == "--fast" ]; then
+        fast=1
+        shift
+    fi
+
+    prev_rev="HEAD~"
 	range=$(rangeish "${1:-}")
 	remap_log=$DIM_PREFIX/maintainer-tools/remap-log
 
@@ -1806,6 +1812,13 @@ function dim_sparse
 	make olddefconfig > /dev/null 2>&1
 	make -j8 drivers/gpu/drm/ > /dev/null 2>&1
 
+    if [ "$fast" == 1 ]; then
+        prev_rev="${commits[0]}~"
+        commits=( "${commits[-1]}" )
+
+        echo "Fast mode used, each commit won't be checked separately."
+    fi
+
 	for commit in "${commits[@]}"; do
 		touch --no-create $(git diff --name-only $commit~...$commit)
 		prev_sr="$(make C=1 -j$(nproc) drivers/gpu/drm/ 2>&1 1>/dev/null)"
@@ -1814,10 +1827,12 @@ function dim_sparse
 		make olddefconfig > /dev/null 2>&1
 		sr="$(make C=1 -j$(nproc) drivers/gpu/drm/ 2>&1 1>/dev/null)"
 
-		prev_remapped="$(echo "$prev_sr" | $remap_log <(git diff HEAD~ | $remap_log))"
+		prev_remapped="$(echo "$prev_sr" | $remap_log <(git diff $prev_rev | $remap_log))"
 		diff_result="$(diff -u <(echo "$prev_remapped" | sort) <(echo "$sr" | sort) || true)"
 
-		echo "Commit: $(git log -n1 --format='%s' $commit)"
+        if [ "$fast" != 1 ]; then
+            echo "Commit: $(git log -n1 --format='%s' $commit)"
+        fi
 		if [ -n "$diff_result" ]; then
 			echo "$diff_result" | grep -E '^[+-]' | grep -E -v '^[+-]{3}'
 		else
diff --git a/dim.rst b/dim.rst
index 792c99f..22d6f56 100644
--- a/dim.rst
+++ b/dim.rst
@@ -79,13 +79,15 @@ filtering. Current profiles are "default", "branch", "drm-intel", and
 "drm-misc". The "branch" profile maps the current git branch to the appropriate
 profile, or if the branch is not known, to "default".
 
-sparse [*commit-ish* [.. *commit-ish*]]
----------------------------------------
-Run sparse on the files changed by the given commit range.
+sparse [--fast] [*commit-ish* [.. *commit-ish*]]
+------------------------------------------------
+Run sparse for each commit in the given commit range.
 
 If no commit-ish is passed, defaults to HEAD^..HEAD. If one commit-ish is passed
 instead of a range, the range commit-ish..HEAD is used.
 
+If --fast is passed we treat the whole range as a single change.
+
 checker
 -------
 Run sparse on drm/i915.
-- 
2.25.4