Merge pull request #1746 from libgit2/rename-detection-performance

Rename detection slow

10 files changed, 458 insertions, 332 deletions

diff --git a/src/array.h b/src/array.h
index 248010425..c25a1b29e 100644
--- a/src/array.h
+++ b/src/array.h
@@ -39,25 +39,26 @@
 #define GITERR_CHECK_ARRAY(a) GITERR_CHECK_ALLOC((a).ptr)
 
 
-typedef git_array_t(void) git_array_generic_t;
+typedef git_array_t(char) git_array_generic_t;
 
 /* use a generic array for growth so this can return the new item */
-GIT_INLINE(void *) git_array_grow(git_array_generic_t *a, size_t item_size)
+GIT_INLINE(void *) git_array_grow(void *_a, size_t item_size)
 {
+	git_array_generic_t *a = _a;
 	uint32_t new_size = (a->size < 8) ? 8 : a->asize * 3 / 2;
-	void *new_array = git__realloc(a->ptr, new_size * item_size);
+	char *new_array = git__realloc(a->ptr, new_size * item_size);
 	if (!new_array) {
 		git_array_clear(*a);
 		return NULL;
 	} else {
 		a->ptr = new_array; a->asize = new_size; a->size++;
-		return (((char *)a->ptr) + (a->size - 1) * item_size);
+		return a->ptr + (a->size - 1) * item_size;
 	}
 }
 
 #define git_array_alloc(a) \
 	((a).size >= (a).asize) ? \
-	git_array_grow((git_array_generic_t *)&(a), sizeof(*(a).ptr)) :	\
+	git_array_grow(&(a), sizeof(*(a).ptr)) : \
 	(a).ptr ? &(a).ptr[(a).size++] : NULL
 
 #define git_array_last(a) ((a).size ? &(a).ptr[(a).size - 1] : NULL)
diff --git a/src/blob.c b/src/blob.c
index 2e4d5f479..5bb51f7cf 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -105,6 +105,7 @@ static int write_file_stream(
 
 static int write_file_filtered(
 	git_oid *oid,
+	git_off_t *size,
 	git_odb *odb,
 	const char *full_path,
 	git_vector *filters)
@@ -123,8 +124,11 @@ static int write_file_filtered(
 	git_buf_free(&source);
 
 	/* Write the file to disk if it was properly filtered */
-	if (!error)
+	if (!error) {
+		*size = dest.size;
+
 		error = git_odb_write(oid, odb, dest.ptr, dest.size, GIT_OBJ_BLOB);
+	}
 
 	git_buf_free(&dest);
 	return error;
@@ -152,21 +156,46 @@ static int write_symlink(
 	return error;
 }
 
-static int blob_create_internal(git_oid *oid, git_repository *repo, const char *content_path, const char *hint_path, bool try_load_filters)
+int git_blob__create_from_paths(
+	git_oid *oid,
+	struct stat *out_st,
+	git_repository *repo,
+	const char *content_path,
+	const char *hint_path,
+	mode_t hint_mode,
+	bool try_load_filters)
 {
 	int error;
 	struct stat st;
 	git_odb *odb = NULL;
 	git_off_t size;
+	mode_t mode;
+	git_buf path = GIT_BUF_INIT;
 
 	assert(hint_path || !try_load_filters);
 
-	if ((error = git_path_lstat(content_path, &st)) < 0 || (error = git_repository_odb__weakptr(&odb, repo)) < 0)
-		return error;
+	if (!content_path) {
+		if (git_repository__ensure_not_bare(repo, "create blob from file") < 0)
+			return GIT_EBAREREPO;
+
+		if (git_buf_joinpath(
+				&path, git_repository_workdir(repo), hint_path) < 0)
+			return -1;
+
+		content_path = path.ptr;
+	}
+
+	if ((error = git_path_lstat(content_path, &st)) < 0 ||
+		(error = git_repository_odb(&odb, repo)) < 0)
+		goto done;
+
+	if (out_st)
+		memcpy(out_st, &st, sizeof(st));
 
 	size = st.st_size;
+	mode = hint_mode ? hint_mode : st.st_mode;
 
-	if (S_ISLNK(st.st_mode)) {
+	if (S_ISLNK(mode)) {
 		error = write_symlink(oid, odb, content_path, (size_t)size);
 	} else {
 		git_vector write_filters = GIT_VECTOR_INIT;
@@ -187,7 +216,8 @@ static int blob_create_internal(git_oid *oid, git_repository *repo, const char *
 			error = write_file_stream(oid, odb, content_path, size);
 		} else {
 			/* We need to apply one or more filters */
-			error = write_file_filtered(oid, odb, content_path, &write_filters);
+			error = write_file_filtered(
+				oid, &size, odb, content_path, &write_filters);
 		}
 
 		git_filters_free(&write_filters);
@@ -207,34 +237,21 @@ static int blob_create_internal(git_oid *oid, git_repository *repo, const char *
 		 */
 	}
 
+done:
+	git_odb_free(odb);
+	git_buf_free(&path);
+
 	return error;
 }
 
-int git_blob_create_fromworkdir(git_oid *oid, git_repository *repo, const char *path)
+int git_blob_create_fromworkdir(
+	git_oid *oid, git_repository *repo, const char *path)
 {
-	git_buf full_path = GIT_BUF_INIT;
-	const char *workdir;
-	int error;
-
-	if ((error = git_repository__ensure_not_bare(repo, "create blob from file")) < 0)
-		return error;
-
-	workdir = git_repository_workdir(repo);
-
-	if (git_buf_joinpath(&full_path, workdir, path) < 0) {
-		git_buf_free(&full_path);
-		return -1;
-	}
-
-	error = blob_create_internal(
-		oid, repo, git_buf_cstr(&full_path),
-		git_buf_cstr(&full_path) + strlen(workdir), true);
-
-	git_buf_free(&full_path);
-	return error;
+	return git_blob__create_from_paths(oid, NULL, repo, NULL, path, 0, true);
 }
 
-int git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *path)
+int git_blob_create_fromdisk(
+	git_oid *oid, git_repository *repo, const char *path)
 {
 	int error;
 	git_buf full_path = GIT_BUF_INIT;
@@ -251,8 +268,8 @@ int git_blob_create_fromdisk(git_oid *oid, git_repository *repo, const char *pat
 	if (workdir && !git__prefixcmp(hintpath, workdir))
 		hintpath += strlen(workdir);
 
-	error = blob_create_internal(
-		oid, repo, git_buf_cstr(&full_path), hintpath, true);
+	error = git_blob__create_from_paths(
+		oid, NULL, repo, git_buf_cstr(&full_path), hintpath, 0, true);
 
 	git_buf_free(&full_path);
 	return error;
@@ -272,12 +289,9 @@ int git_blob_create_fromchunks(
 	git_filebuf file = GIT_FILEBUF_INIT;
 	git_buf path = GIT_BUF_INIT;
 
-	if (git_buf_join_n(
-		&path, '/', 3, 
-		git_repository_path(repo),
-		GIT_OBJECTS_DIR, 
-		"streamed") < 0)
-			goto cleanup;
+	if (git_buf_joinpath(
+			&path, git_repository_path(repo), GIT_OBJECTS_DIR "streamed") < 0)
+		goto cleanup;
 
 	content = git__malloc(BUFFER_SIZE);
 	GITERR_CHECK_ALLOC(content);
@@ -303,7 +317,8 @@ int git_blob_create_fromchunks(
 	if (git_filebuf_flush(&file) < 0)
 		goto cleanup;
 
-	error = blob_create_internal(oid, repo, file.path_lock, hintpath, hintpath != NULL);
+	error = git_blob__create_from_paths(
+		oid, NULL, repo, file.path_lock, hintpath, 0, hintpath != NULL);
 
 cleanup:
 	git_buf_free(&path);
diff --git a/src/blob.h b/src/blob.h
index 22e37cc3a..4cd9f1e0c 100644
--- a/src/blob.h
+++ b/src/blob.h
@@ -21,4 +21,13 @@ void git_blob__free(void *blob);
 int git_blob__parse(void *blob, git_odb_object *obj);
 int git_blob__getbuf(git_buf *buffer, git_blob *blob);
 
+extern int git_blob__create_from_paths(
+	git_oid *out_oid,
+	struct stat *out_st,
+	git_repository *repo,
+	const char *full_path,
+	const char *hint_path,
+	mode_t hint_mode,
+	bool apply_filters);
+
 #endif
diff --git a/src/diff.h b/src/diff.h
index d09a130bc..d1bec00c6 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -16,6 +16,7 @@
 #include "iterator.h"
 #include "repository.h"
 #include "pool.h"
+#include "odb.h"
 
 #define DIFF_OLD_PREFIX_DEFAULT "a/"
 #define DIFF_NEW_PREFIX_DEFAULT "b/"
@@ -108,5 +109,33 @@ extern void git_diff_find_similar__hashsig_free(void *sig, void *payload);
 extern int git_diff_find_similar__calc_similarity(
 	int *score, void *siga, void *sigb, void *payload);
 
+/*
+ * Sometimes a git_diff_file will have a zero size; this attempts to
+ * fill in the size without loading the blob if possible.  If that is
+ * not possible, then it will return the git_odb_object that had to be
+ * loaded and the caller can use it or dispose of it as needed.
+ */
+GIT_INLINE(int) git_diff_file__resolve_zero_size(
+	git_diff_file *file, git_odb_object **odb_obj, git_repository *repo)
+{
+	int error;
+	git_odb *odb;
+	size_t len;
+	git_otype type;
+
+	if ((error = git_repository_odb(&odb, repo)) < 0)
+		return error;
+
+	error = git_odb__read_header_or_object(
+		odb_obj, &len, &type, odb, &file->oid);
+
+	git_odb_free(odb);
+
+	if (!error)
+		file->size = (git_off_t)len;
+
+	return error;
+}
+
 #endif
 
diff --git a/src/diff_file.c b/src/diff_file.c
index 9d06daafa..bcfef13cd 100644
--- a/src/diff_file.c
+++ b/src/diff_file.c
@@ -241,19 +241,9 @@ static int diff_file_content_load_blob(git_diff_file_content *fc)
 
 	/* if we don't know size, try to peek at object header first */
 	if (!fc->file->size) {
-		git_odb *odb;
-		size_t len;
-		git_otype type;
-
-		if (!(error = git_repository_odb__weakptr(&odb, fc->repo))) {
-			error = git_odb__read_header_or_object(
-				&odb_obj, &len, &type, odb, &fc->file->oid);
-			git_odb_free(odb);
-		}
-		if (error)
+		if ((error = git_diff_file__resolve_zero_size(
+				fc->file, &odb_obj, fc->repo)) < 0)
 			return error;
-
-		fc->file->size = len;
 	}
 
 	if (diff_file_content_binary_by_size(fc))
@@ -417,6 +407,9 @@ int git_diff_file_content__load(git_diff_file_content *fc)
 
 void git_diff_file_content__unload(git_diff_file_content *fc)
 {
+	if ((fc->flags & GIT_DIFF_FLAG__LOADED) == 0)
+		return;
+
 	if (fc->flags & GIT_DIFF_FLAG__FREE_DATA) {
 		git__free(fc->map.data);
 		fc->map.data = "";
diff --git a/src/diff_patch.c b/src/diff_patch.c
index 1b4adac03..69bb08198 100644
--- a/src/diff_patch.c
+++ b/src/diff_patch.c
@@ -230,6 +230,10 @@ static int diff_patch_generate(git_diff_patch *patch, git_diff_output *output)
 	if ((patch->flags & GIT_DIFF_PATCH_DIFFED) != 0)
 		return 0;
 
+	/* if we are not looking at the hunks and lines, don't do the diff */
+	if (!output->hunk_cb && !output->data_cb)
+		return 0;
+
 	if ((patch->flags & GIT_DIFF_PATCH_LOADED) == 0 &&
 		(error = diff_patch_load(patch, output)) < 0)
 		return error;
@@ -284,8 +288,8 @@ int git_diff_foreach(
 	if (diff_required(diff, "git_diff_foreach") < 0)
 		return -1;
 
-	diff_output_init((git_diff_output *)&xo,
-		&diff->opts, file_cb, hunk_cb, data_cb, payload);
+	diff_output_init(
+		&xo.output, &diff->opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, &diff->opts);
 
 	git_vector_foreach(&diff->deltas, idx, patch.delta) {
@@ -296,10 +300,10 @@ int git_diff_foreach(
 
 		if (!(error = diff_patch_init_from_diff(&patch, diff, idx))) {
 
-			error = diff_patch_file_callback(&patch, (git_diff_output *)&xo);
+			error = diff_patch_file_callback(&patch, &xo.output);
 
 			if (!error)
-				error = diff_patch_generate(&patch, (git_diff_output *)&xo);
+				error = diff_patch_generate(&patch, &xo.output);
 
 			git_diff_patch_free(&patch);
 		}
@@ -437,7 +441,7 @@ int git_diff_blobs(
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_init(
-		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
+		&xo.output, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
 	if (!old_path && new_path)
@@ -448,7 +452,7 @@ int git_diff_blobs(
 	error = diff_patch_from_blobs(
 		&pd, &xo, old_blob, old_path, new_blob, new_path, opts);
 
-	git_diff_patch_free((git_diff_patch *)&pd);
+	git_diff_patch_free(&pd.patch);
 
 	return error;
 }
@@ -473,7 +477,7 @@ int git_diff_patch_from_blobs(
 
 	memset(&xo, 0, sizeof(xo));
 
-	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
+	diff_output_to_patch(&xo.output, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
 	error = diff_patch_from_blobs(
@@ -549,7 +553,7 @@ int git_diff_blob_to_buffer(
 	memset(&xo, 0, sizeof(xo));
 
 	diff_output_init(
-		(git_diff_output *)&xo, opts, file_cb, hunk_cb, data_cb, payload);
+		&xo.output, opts, file_cb, hunk_cb, data_cb, payload);
 	git_xdiff_init(&xo, opts);
 
 	if (!old_path && buf_path)
@@ -560,7 +564,7 @@ int git_diff_blob_to_buffer(
 	error = diff_patch_from_blob_and_buffer(
 		&pd, &xo, old_blob, old_path, buf, buflen, buf_path, opts);
 
-	git_diff_patch_free((git_diff_patch *)&pd);
+	git_diff_patch_free(&pd.patch);
 
 	return error;
 }
@@ -586,7 +590,7 @@ int git_diff_patch_from_blob_and_buffer(
 
 	memset(&xo, 0, sizeof(xo));
 
-	diff_output_to_patch((git_diff_output *)&xo, &pd->patch);
+	diff_output_to_patch(&xo.output, &pd->patch);
 	git_xdiff_init(&xo, opts);
 
 	error = diff_patch_from_blob_and_buffer(
@@ -638,13 +642,13 @@ int git_diff_get_patch(
 	if ((error = diff_patch_alloc_from_diff(&patch, diff, idx)) < 0)
 		return error;
 
-	diff_output_to_patch((git_diff_output *)&xo, patch);
+	diff_output_to_patch(&xo.output, patch);
 	git_xdiff_init(&xo, &diff->opts);
 
-	error = diff_patch_file_callback(patch, (git_diff_output *)&xo);
+	error = diff_patch_file_callback(patch, &xo.output);
 
 	if (!error)
-		error = diff_patch_generate(patch, (git_diff_output *)&xo);
+		error = diff_patch_generate(patch, &xo.output);
 
 	if (!error) {
 		/* if cumulative diff size is < 0.5 total size, flatten the patch */
diff --git a/src/diff_tform.c b/src/diff_tform.c
index ac5356a8c..ba35d3c14 100644
--- a/src/diff_tform.c
+++ b/src/diff_tform.c
@@ -408,57 +408,99 @@ GIT_INLINE(git_diff_file *) similarity_get_file(git_diff_list *diff, size_t idx)
 	return (idx & 1) ? &delta->new_file : &delta->old_file;
 }
 
-static int similarity_calc(
-	git_diff_list *diff,
+typedef struct {
+	size_t idx;
+	git_iterator_type_t src;
+	git_repository *repo;
+	git_diff_file *file;
+	git_buf data;
+	git_odb_object *odb_obj;
+	git_blob *blob;
+} similarity_info;
+
+static int similarity_init(
+	similarity_info *info, git_diff_list *diff, size_t file_idx)
+{
+	info->idx  = file_idx;
+	info->src  = (file_idx & 1) ? diff->new_src : diff->old_src;
+	info->repo = diff->repo;
+	info->file = similarity_get_file(diff, file_idx);
+	info->odb_obj = NULL;
+	info->blob = NULL;
+	git_buf_init(&info->data, 0);
+
+	if (info->file->size > 0)
+		return 0;
+
+	return git_diff_file__resolve_zero_size(
+		info->file, &info->odb_obj, info->repo);
+}
+
+static int similarity_sig(
+	similarity_info *info,
 	const git_diff_find_options *opts,
-	size_t file_idx,
 	void **cache)
 {
 	int error = 0;
-	git_diff_file *file = similarity_get_file(diff, file_idx);
-	git_iterator_type_t src = (file_idx & 1) ? diff->new_src : diff->old_src;
-
-	if (src == GIT_ITERATOR_TYPE_WORKDIR) { /* compute hashsig from file */
-		git_buf path = GIT_BUF_INIT;
-
-		/* TODO: apply wd-to-odb filters to file data if necessary */
+	git_diff_file *file = info->file;
 
+	if (info->src == GIT_ITERATOR_TYPE_WORKDIR) {
 		if ((error = git_buf_joinpath(
-				 &path, git_repository_workdir(diff->repo), file->path)) < 0)
+			&info->data, git_repository_workdir(info->repo), file->path)) < 0)
 			return error;
 
 		/* if path is not a regular file, just skip this item */
-		if (git_path_isfile(path.ptr))
-			error = opts->metric->file_signature(
-				&cache[file_idx], file, path.ptr, opts->metric->payload);
+		if (!git_path_isfile(info->data.ptr))
+			return 0;
 
-		git_buf_free(&path);
-	} else { /* compute hashsig from blob buffer */
-		git_blob *blob = NULL;
-		git_off_t blobsize;
+		/* TODO: apply wd-to-odb filters to file data if necessary */
 
-		/* TODO: add max size threshold a la diff? */
+		error = opts->metric->file_signature(
+			&cache[info->idx], info->file,
+			info->data.ptr, opts->metric->payload);
+	} else {
+		/* if we didn't initially know the size, we might have an odb_obj
+		 * around from earlier, so convert that, otherwise load the blob now
+		 */
+		if (info->odb_obj != NULL)
+			error = git_object__from_odb_object(
+				(git_object **)&info->blob, info->repo,
+				info->odb_obj, GIT_OBJ_BLOB);
+		else
+			error = git_blob_lookup(&info->blob, info->repo, &file->oid);
 
-		if (git_blob_lookup(&blob, diff->repo, &file->oid) < 0) {
+		if (error < 0) {
 			/* if lookup fails, just skip this item in similarity calc */
 			giterr_clear();
-			return 0;
-		}
+		} else {
+			size_t sz;
 
-		blobsize = git_blob_rawsize(blob);
-		if (!git__is_sizet(blobsize)) /* ? what to do ? */
-			blobsize = (size_t)-1;
+			/* index size may not be actual blob size if filtered */
+			if (file->size != git_blob_rawsize(info->blob))
+				file->size = git_blob_rawsize(info->blob);
 
-		error = opts->metric->buffer_signature(
-			&cache[file_idx], file, git_blob_rawcontent(blob),
-			(size_t)blobsize, opts->metric->payload);
+			sz = (size_t)(git__is_sizet(file->size) ? file->size : -1);
 
-		git_blob_free(blob);
+			error = opts->metric->buffer_signature(
+				&cache[info->idx], info->file,
+				git_blob_rawcontent(info->blob), sz, opts->metric->payload);
+		}
 	}
 
 	return error;
 }
 
+static void similarity_unload(similarity_info *info)
+{
+	if (info->odb_obj)
+		git_odb_object_free(info->odb_obj);
+
+	if (info->blob)
+		git_blob_free(info->blob);
+	else
+		git_buf_free(&info->data);
+}
+
 #define FLAG_SET(opts,flag_name) (((opts)->flags & flag_name) != 0)
 
 /* - score < 0 means files cannot be compared
@@ -476,6 +518,8 @@ static int similarity_measure(
 	git_diff_file *a_file = similarity_get_file(diff, a_idx);
 	git_diff_file *b_file = similarity_get_file(diff, b_idx);
 	bool exact_match = FLAG_SET(opts, GIT_DIFF_FIND_EXACT_MATCH_ONLY);
+	int error = 0;
+	similarity_info a_info, b_info;
 
 	*score = -1;
 
@@ -510,19 +554,44 @@ static int similarity_measure(
 		return 0;
 	}
 
+	memset(&a_info, 0, sizeof(a_info));
+	memset(&b_info, 0, sizeof(b_info));
+
+	/* set up similarity data (will try to update missing file sizes) */
+	if (!cache[a_idx] && (error = similarity_init(&a_info, diff, a_idx)) < 0)
+		return error;
+	if (!cache[b_idx] && (error = similarity_init(&b_info, diff, b_idx)) < 0)
+		goto cleanup;
+
+	/* check if file sizes are nowhere near each other */
+	if (a_file->size > 127 &&
+		b_file->size > 127 &&
+		(a_file->size > (b_file->size << 3) ||
+		 b_file->size > (a_file->size << 3)))
+		goto cleanup;
+
 	/* update signature cache if needed */
-	if (!cache[a_idx] && similarity_calc(diff, opts, a_idx, cache) < 0)
-		return -1;
-	if (!cache[b_idx] && similarity_calc(diff, opts, b_idx, cache) < 0)
-		return -1;
+	if (!cache[a_idx]) {
+		if ((error = similarity_sig(&a_info, opts, cache)) < 0)
+			goto cleanup;
+	}
+	if (!cache[b_idx]) {
+		if ((error = similarity_sig(&b_info, opts, cache)) < 0)
+			goto cleanup;
+	}
 
-	/* some metrics may not wish to process this file (too big / too small) */
-	if (!cache[a_idx] || !cache[b_idx])
-		return 0;
+	/* calculate similarity provided that the metric choose to process
+	 * both the a and b files (some may not if file is too big, etc).
+	 */
+	if (cache[a_idx] && cache[b_idx])
+		error = opts->metric->similarity(
+			score, cache[a_idx], cache[b_idx], opts->metric->payload);
+
+cleanup:
+	similarity_unload(&a_info);
+	similarity_unload(&b_info);
 
-	/* compare signatures */
-	return opts->metric->similarity(
-		score, cache[a_idx], cache[b_idx], opts->metric->payload);
+	return error;
 }
 
 static int calc_self_similarity(
@@ -693,25 +762,30 @@ int git_diff_find_similar(
 	git_diff_list *diff,
 	git_diff_find_options *given_opts)
 {
-	size_t i, j, sigcache_size;
+	size_t s, t;
 	int error = 0, similarity;
-	git_diff_delta *from, *to;
+	git_diff_delta *src, *tgt;
 	git_diff_find_options opts;
-	size_t num_srcs = 0, num_tgts = 0, tried_srcs = 0, tried_tgts = 0;
+	size_t num_deltas, num_srcs = 0, num_tgts = 0;
+	size_t tried_srcs = 0, tried_tgts = 0;
 	size_t num_rewrites = 0, num_updates = 0, num_bumped = 0;
 	void **sigcache; /* cache of similarity metric file signatures */
-	diff_find_match *match_srcs = NULL, *match_tgts = NULL, *best_match;
+	diff_find_match *tgt2src = NULL;
+	diff_find_match *src2tgt = NULL;
+	diff_find_match *tgt2src_copy = NULL;
+	diff_find_match *best_match;
 	git_diff_file swap;
 
 	if ((error = normalize_find_opts(diff, &opts, given_opts)) < 0)
 		return error;
 
+	num_deltas = diff->deltas.length;
+
 	/* TODO: maybe abort if deltas.length > rename_limit ??? */
-	if (!git__is_uint32(diff->deltas.length))
+	if (!git__is_uint32(num_deltas))
 		return 0;
 
-	sigcache_size = diff->deltas.length * 2; /* keep size b/c diff may change */
-	sigcache = git__calloc(sigcache_size, sizeof(void *));
+	sigcache = git__calloc(num_deltas * 2, sizeof(void *));
 	GITERR_CHECK_ALLOC(sigcache);
 
 	/* Label rename sources and targets
@@ -719,11 +793,11 @@ int git_diff_find_similar(
 	 * This will also set self-similarity scores for MODIFIED files and
 	 * mark them for splitting if break-rewrites is enabled
 	 */
-	git_vector_foreach(&diff->deltas, i, to) {
-		if (is_rename_source(diff, &opts, i, sigcache))
+	git_vector_foreach(&diff->deltas, t, tgt) {
+		if (is_rename_source(diff, &opts, t, sigcache))
 			++num_srcs;
 
-		if (is_rename_target(diff, &opts, i, sigcache))
+		if (is_rename_target(diff, &opts, t, sigcache))
 			++num_tgts;
 	}
 
@@ -731,10 +805,15 @@ int git_diff_find_similar(
 	if (!num_srcs || !num_tgts)
 		goto cleanup;
 
-	match_tgts = git__calloc(diff->deltas.length, sizeof(diff_find_match));
-	GITERR_CHECK_ALLOC(match_tgts);
-	match_srcs = git__calloc(diff->deltas.length, sizeof(diff_find_match));
-	GITERR_CHECK_ALLOC(match_srcs);
+	src2tgt = git__calloc(num_deltas, sizeof(diff_find_match));
+	GITERR_CHECK_ALLOC(src2tgt);
+	tgt2src = git__calloc(num_deltas, sizeof(diff_find_match));
+	GITERR_CHECK_ALLOC(tgt2src);
+
+	if (FLAG_SET(&opts, GIT_DIFF_FIND_COPIES)) {
+		tgt2src_copy = git__calloc(num_deltas, sizeof(diff_find_match));
+		GITERR_CHECK_ALLOC(tgt2src_copy);
+	}
 
 	/*
 	 * Find best-fit matches for rename / copy candidates
@@ -743,47 +822,61 @@ int git_diff_find_similar(
 find_best_matches:
 	tried_tgts = num_bumped = 0;
 
-	git_vector_foreach(&diff->deltas, i, to) {
+	git_vector_foreach(&diff->deltas, t, tgt) {
 		/* skip things that are not rename targets */
-		if ((to->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
+		if ((tgt->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
 			continue;
 
 		tried_srcs = 0;
 
-		git_vector_foreach(&diff->deltas, j, from) {
+		git_vector_foreach(&diff->deltas, s, src) {
 			/* skip things that are not rename sources */
-			if ((from->flags & GIT_DIFF_FLAG__IS_RENAME_SOURCE) == 0)
+			if ((src->flags & GIT_DIFF_FLAG__IS_RENAME_SOURCE) == 0)
 				continue;
 
 			/* calculate similarity for this pair and find best match */
-			if (i == j)
+			if (s == t)
 				similarity = -1; /* don't measure self-similarity here */
 			else if ((error = similarity_measure(
-				&similarity, diff, &opts, sigcache, 2 * j, 2 * i + 1)) < 0)
+				&similarity, diff, &opts, sigcache, 2 * s, 2 * t + 1)) < 0)
 				goto cleanup;
 
-			/* if this pairing is better for the src and the tgt, keep it */
-			if (similarity > 0 &&
-				match_tgts[i].similarity < (uint32_t)similarity &&
-				match_srcs[j].similarity < (uint32_t)similarity)
+			if (similarity < 0)
+				continue;
+
+			/* is this a better rename? */
+			if (tgt2src[t].similarity < (uint32_t)similarity &&
+				src2tgt[s].similarity < (uint32_t)similarity)
 			{
-				if (match_tgts[i].similarity > 0) {
-					match_tgts[match_srcs[j].idx].similarity = 0;
-					match_srcs[match_tgts[i].idx].similarity = 0;
-					++num_bumped;
+				/* eject old mapping */
+				if (src2tgt[s].similarity > 0) {
+					tgt2src[src2tgt[s].idx].similarity = 0;
+					num_bumped++;
+				}
+				if (tgt2src[t].similarity > 0) {
+					src2tgt[tgt2src[t].idx].similarity = 0;
+					num_bumped++;
 				}
 
-				match_tgts[i].similarity = (uint32_t)similarity;
-				match_tgts[i].idx = (uint32_t)j;
+				/* write new mapping */
+				tgt2src[t].idx = s;
+				tgt2src[t].similarity = (uint32_t)similarity;
+				src2tgt[s].idx = t;
+				src2tgt[s].similarity = (uint32_t)similarity;
+			}
 
-				match_srcs[j].similarity = (uint32_t)similarity;
-				match_srcs[j].idx = (uint32_t)i;
+			/* keep best absolute match for copies */
+			if (tgt2src_copy != NULL &&
+				tgt2src_copy[t].similarity < (uint32_t)similarity)
+			{
+				tgt2src_copy[t].idx = s;
+				tgt2src_copy[t].similarity = (uint32_t)similarity;
 			}
 
 			if (++tried_srcs >= num_srcs)
 				break;
 
-			/* cap on maximum targets we'll examine (per "to" file) */
+			/* cap on maximum targets we'll examine (per "tgt" file) */
 			if (tried_srcs > opts.rename_limit)
 				break;
 		}
@@ -801,18 +894,21 @@ find_best_matches:
 
 	tried_tgts = 0;
 
-	git_vector_foreach(&diff->deltas, i, to) {
+	git_vector_foreach(&diff->deltas, t, tgt) {
 		/* skip things that are not rename targets */
-		if ((to->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
+		if ((tgt->flags & GIT_DIFF_FLAG__IS_RENAME_TARGET) == 0)
 			continue;
 
 		/* check if this delta was the target of a similarity */
-		best_match = &match_tgts[i];
-		if (!best_match->similarity)
+		if (tgt2src[t].similarity)
+			best_match = &tgt2src[t];
+		else if (tgt2src_copy && tgt2src_copy[t].similarity)
+			best_match = &tgt2src_copy[t];
+		else
 			continue;
 
-		j = best_match->idx;
-		from = GIT_VECTOR_GET(&diff->deltas, j);
+		s = best_match->idx;
+		src = GIT_VECTOR_GET(&diff->deltas, s);
 
 		/* possible scenarios:
 		 * 1. from DELETE to ADD/UNTRACK/IGNORE = RENAME
@@ -822,101 +918,112 @@ find_best_matches:
 		 * 5. from OTHER to ADD/UNTRACK/IGNORE = OTHER + COPY
 		 */
 
-		if (from->status == GIT_DELTA_DELETED) {
+		if (src->status == GIT_DELTA_DELETED) {
 
-			if (delta_is_new_only(to)) {
+			if (delta_is_new_only(tgt)) {
 
 				if (best_match->similarity < opts.rename_threshold)
 					continue;
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 
-				from->flags |= GIT_DIFF_FLAG__TO_DELETE;
+				src->flags |= GIT_DIFF_FLAG__TO_DELETE;
 				num_rewrites++;
 			} else {
-				assert(delta_is_split(to));
+				assert(delta_is_split(tgt));
 
 				if (best_match->similarity < opts.rename_from_rewrite_threshold)
 					continue;
 
-				memcpy(&swap, &to->old_file, sizeof(swap));
+				memcpy(&swap, &tgt->old_file, sizeof(swap));
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 				num_rewrites--;
 
-				from->status = GIT_DELTA_DELETED;
-				memcpy(&from->old_file, &swap, sizeof(from->old_file));
-				memset(&from->new_file, 0, sizeof(from->new_file));
-				from->new_file.path = from->old_file.path;
-				from->new_file.flags |= GIT_DIFF_FLAG_VALID_OID;
+				src->status = GIT_DELTA_DELETED;
+				memcpy(&src->old_file, &swap, sizeof(src->old_file));
+				memset(&src->new_file, 0, sizeof(src->new_file));
+				src->new_file.path = src->old_file.path;
+				src->new_file.flags |= GIT_DIFF_FLAG_VALID_OID;
 
 				num_updates++;
+
+				if (src2tgt[t].similarity > 0 && src2tgt[t].idx > t) {
+					/* what used to be at src t is now at src s */
+					tgt2src[src2tgt[t].idx].idx = (uint32_t)s;
+				}
 			}
 		}
 
-		else if (delta_is_split(from)) {
+		else if (delta_is_split(src)) {
 
-			if (delta_is_new_only(to)) {
+			if (delta_is_new_only(tgt)) {
 
 				if (best_match->similarity < opts.rename_threshold)
 					continue;
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 
-				from->status = (diff->new_src == GIT_ITERATOR_TYPE_WORKDIR) ?
+				src->status = (diff->new_src == GIT_ITERATOR_TYPE_WORKDIR) ?
 					GIT_DELTA_UNTRACKED : GIT_DELTA_ADDED;
-				memset(&from->old_file, 0, sizeof(from->old_file));
-				from->old_file.path = from->new_file.path;
-				from->old_file.flags |= GIT_DIFF_FLAG_VALID_OID;
+				memset(&src->old_file, 0, sizeof(src->old_file));
+				src->old_file.path = src->new_file.path;
+				src->old_file.flags |= GIT_DIFF_FLAG_VALID_OID;
 
-				from->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
+				src->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
 				num_rewrites--;
 
 				num_updates++;
 			} else {
-				assert(delta_is_split(from));
+				assert(delta_is_split(src));
 
 				if (best_match->similarity < opts.rename_from_rewrite_threshold)
 					continue;
 
-				memcpy(&swap, &to->old_file, sizeof(swap));
+				memcpy(&swap, &tgt->old_file, sizeof(swap));
 
-				delta_make_rename(to, from, best_match->similarity);
+				delta_make_rename(tgt, src, best_match->similarity);
 				num_rewrites--;
 				num_updates++;
 
-				memcpy(&from->old_file, &swap, sizeof(from->old_file));
+				memcpy(&src->old_file, &swap, sizeof(src->old_file));
 
 				/* if we've just swapped the new element into the correct
 				 * place, clear the SPLIT flag
 				 */
-				if (match_tgts[j].idx == i &&
-					match_tgts[j].similarity >
+				if (tgt2src[s].idx == t &&
+					tgt2src[s].similarity >
 					opts.rename_from_rewrite_threshold) {
-
-					from->status     = GIT_DELTA_RENAMED;
-					from->similarity = match_tgts[j].similarity;
-					match_tgts[j].similarity = 0;
-					from->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
+					src->status     = GIT_DELTA_RENAMED;
+					src->similarity = tgt2src[s].similarity;
+					tgt2src[s].similarity = 0;
+					src->flags &= ~GIT_DIFF_FLAG__TO_SPLIT;
 					num_rewrites--;
 				}
 				/* otherwise, if we just overwrote a source, update mapping */
-				else if (j > i && match_srcs[i].similarity > 0) {
-					match_tgts[match_srcs[i].idx].idx = (uint32_t)j;
+				else if (src2tgt[t].similarity > 0 && src2tgt[t].idx > t) {
+					/* what used to be at src t is now at src s */
+					tgt2src[src2tgt[t].idx].idx = (uint32_t)s;
 				}
 
 				num_updates++;
 			}
 		}
 
-		else if (delta_is_new_only(to)) {
-			if (!FLAG_SET(&opts, GIT_DIFF_FIND_COPIES) ||
-				best_match->similarity < opts.copy_threshold)
+		else if (delta_is_new_only(tgt)) {
+			if (!FLAG_SET(&opts, GIT_DIFF_FIND_COPIES))
 				continue;
 
-			to->status     = GIT_DELTA_COPIED;
-			to->similarity = best_match->similarity;
-			memcpy(&to->old_file, &from->old_file, sizeof(to->old_file));
+			if (tgt2src_copy[t].similarity < opts.copy_threshold)
+				continue;
+
+			/* always use best possible source for copy */
+			best_match = &tgt2src_copy[t];
+			src = GIT_VECTOR_GET(&diff->deltas, best_match->idx);
+
+			tgt->status     = GIT_DELTA_COPIED;
+			tgt->similarity = best_match->similarity;
+			memcpy(&tgt->old_file, &src->old_file, sizeof(tgt->old_file));
 
 			num_updates++;
 		}
@@ -932,12 +1039,13 @@ find_best_matches:
 			FLAG_SET(&opts, GIT_DIFF_BREAK_REWRITES));
 
 cleanup:
-	git__free(match_srcs);
-	git__free(match_tgts);
+	git__free(tgt2src);
+	git__free(src2tgt);
+	git__free(tgt2src_copy);
 
-	for (i = 0; i < sigcache_size; ++i) {
-		if (sigcache[i] != NULL)
-			opts.metric->free_signature(sigcache[i], opts.metric->payload);
+	for (t = 0; t < num_deltas * 2; ++t) {
+		if (sigcache[t] != NULL)
+			opts.metric->free_signature(sigcache[t], opts.metric->payload);
 	}
 	git__free(sigcache);
 
diff --git a/src/hashsig.c b/src/hashsig.c
index ab8d8b3f0..109f966ba 100644
--- a/src/hashsig.c
+++ b/src/hashsig.c
@@ -13,12 +13,15 @@ typedef uint64_t hashsig_state;
 
 #define HASHSIG_SCALE 100
 
-#define HASHSIG_HASH_WINDOW 32
-#define HASHSIG_HASH_START	0
+#define HASHSIG_MAX_RUN 80
+#define HASHSIG_HASH_START	0x012345678ABCDEF0LL
 #define HASHSIG_HASH_SHIFT  5
-#define HASHSIG_HASH_MASK   0x7FFFFFFF
+
+#define HASHSIG_HASH_MIX(S,CH) \
+	(S) = ((S) << HASHSIG_HASH_SHIFT) - (S) + (hashsig_state)(CH)
 
 #define HASHSIG_HEAP_SIZE ((1 << 7) - 1)
+#define HASHSIG_HEAP_MIN_SIZE 4
 
 typedef int (*hashsig_cmp)(const void *a, const void *b, void *);
 
@@ -28,14 +31,6 @@ typedef struct {
 	hashsig_t values[HASHSIG_HEAP_SIZE];
 } hashsig_heap;
 
-typedef struct {
-	hashsig_state state, shift_n;
-	char window[HASHSIG_HASH_WINDOW];
-	int win_len, win_pos, saw_lf;
-} hashsig_in_progress;
-
-#define HASHSIG_IN_PROGRESS_INIT { HASHSIG_HASH_START, 1, {0}, 0, 0, 1 }
-
 struct git_hashsig {
 	hashsig_heap mins;
 	hashsig_heap maxs;
@@ -43,8 +38,8 @@ struct git_hashsig {
 	int considered;
 };
 
-#define HEAP_LCHILD_OF(I) (((I)*2)+1)
-#define HEAP_RCHILD_OF(I) (((I)*2)+2)
+#define HEAP_LCHILD_OF(I) (((I)<<1)+1)
+#define HEAP_RCHILD_OF(I) (((I)<<1)+2)
 #define HEAP_PARENT_OF(I) (((I)-1)>>1)
 
 static void hashsig_heap_init(hashsig_heap *h, hashsig_cmp cmp)
@@ -115,134 +110,109 @@ static void hashsig_heap_sort(hashsig_heap *h)
 
 static void hashsig_heap_insert(hashsig_heap *h, hashsig_t val)
 {
-	/* if heap is full, pop top if new element should replace it */
-	if (h->size == h->asize && h->cmp(&val, &h->values[0], NULL) > 0) {
-		h->size--;
-		h->values[0] = h->values[h->size];
-		hashsig_heap_down(h, 0);
-	}
-
 	/* if heap is not full, insert new element */
 	if (h->size < h->asize) {
 		h->values[h->size++] = val;
 		hashsig_heap_up(h, h->size - 1);
 	}
-}
-
-GIT_INLINE(bool) hashsig_include_char(
-	char ch, git_hashsig_option_t opt, int *saw_lf)
-{
-	if ((opt & GIT_HASHSIG_IGNORE_WHITESPACE) && git__isspace(ch))
-		return false;
-
-	if (opt & GIT_HASHSIG_SMART_WHITESPACE) {
-		if (ch == '\r' || (*saw_lf && git__isspace(ch)))
-			return false;
 
-		*saw_lf = (ch == '\n');
+	/* if heap is full, pop top if new element should replace it */
+	else if (h->cmp(&val, &h->values[0], NULL) > 0) {
+		h->size--;
+		h->values[0] = h->values[h->size];
+		hashsig_heap_down(h, 0);
 	}
 
-	return true;
 }
 
-static void hashsig_initial_window(
-	git_hashsig *sig,
-	const char **data,
-	size_t size,
-	hashsig_in_progress *prog)
-{
-	hashsig_state state, shift_n;
-	int win_len;
-	const char *scan, *end;
-
-	/* init until we have processed at least HASHSIG_HASH_WINDOW data */
-
-	if (prog->win_len >= HASHSIG_HASH_WINDOW)
-		return;
-
-	state   = prog->state;
-	win_len = prog->win_len;
-	shift_n = prog->shift_n;
-
-	scan = *data;
-	end  = scan + size;
-
-	while (scan < end && win_len < HASHSIG_HASH_WINDOW) {
-		char ch = *scan++;
-
-		if (!hashsig_include_char(ch, sig->opt, &prog->saw_lf))
-			continue;
-
-		state = (state * HASHSIG_HASH_SHIFT + ch) & HASHSIG_HASH_MASK;
-
-		if (!win_len)
-			shift_n = 1;
-		else
-			shift_n = (shift_n * HASHSIG_HASH_SHIFT) & HASHSIG_HASH_MASK;
-
-		prog->window[win_len++] = ch;
-	}
-
-	/* insert initial hash if we just finished */
+typedef struct {
+	int use_ignores;
+	uint8_t ignore_ch[256];
+} hashsig_in_progress;
 
-	if (win_len == HASHSIG_HASH_WINDOW) {
-		hashsig_heap_insert(&sig->mins, (hashsig_t)state);
-		hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
-		sig->considered = 1;
+static void hashsig_in_progress_init(
+	hashsig_in_progress *prog, git_hashsig *sig)
+{
+	int i;
+
+	switch (sig->opt) {
+	case GIT_HASHSIG_IGNORE_WHITESPACE:
+		for (i = 0; i < 256; ++i)
+			prog->ignore_ch[i] = git__isspace_nonlf(i);
+		prog->use_ignores = 1;
+		break;
+	case GIT_HASHSIG_SMART_WHITESPACE:
+		for (i = 0; i < 256; ++i)
+			prog->ignore_ch[i] = git__isspace(i);
+		prog->use_ignores = 1;
+		break;
+	default:
+		memset(prog, 0, sizeof(*prog));
+		break;
 	}
-
-	prog->state   = state;
-	prog->win_len = win_len;
-	prog->shift_n = shift_n;
-
-	*data = scan;
 }
 
+#define HASHSIG_IN_PROGRESS_INIT { 1 }
+
 static int hashsig_add_hashes(
 	git_hashsig *sig,
-	const char *data,
+	const uint8_t *data,
 	size_t size,
 	hashsig_in_progress *prog)
 {
-	const char *scan = data, *end = data + size;
-	hashsig_state state, shift_n, rmv;
-
-	if (prog->win_len < HASHSIG_HASH_WINDOW)
-		hashsig_initial_window(sig, &scan, size, prog);
-
-	state   = prog->state;
-	shift_n = prog->shift_n;
-
-	/* advance window, adding new chars and removing old */
-
-	for (; scan < end; ++scan) {
-		char ch = *scan;
-
-		if (!hashsig_include_char(ch, sig->opt, &prog->saw_lf))
-			continue;
-
-		rmv = shift_n * prog->window[prog->win_pos];
+	const uint8_t *scan = data, *end = data + size;
+	hashsig_state state = HASHSIG_HASH_START;
+	int use_ignores = prog->use_ignores, len;
+	uint8_t ch;
+
+	while (scan < end) {
+		state = HASHSIG_HASH_START;
+
+		for (len = 0; scan < end && len < HASHSIG_MAX_RUN; ) {
+			ch = *scan;
+
+			if (use_ignores)
+				for (; scan < end && git__isspace_nonlf(ch); ch = *scan)
+					++scan;
+			else if (sig->opt != GIT_HASHSIG_NORMAL)
+				for (; scan < end && ch == '\r'; ch = *scan)
+					++scan;
+
+			/* peek at next character to decide what to do next */
+			if (sig->opt == GIT_HASHSIG_SMART_WHITESPACE)
+				use_ignores = (ch == '\n');
+
+			if (scan >= end)
+				break;
+			++scan;
+
+			/* check run terminator */
+			if (ch == '\n' || ch == '\0')
+				break;
+
+			++len;
+			HASHSIG_HASH_MIX(state, ch);
+		}
 
-		state = (state - rmv) & HASHSIG_HASH_MASK;
-		state = (state * HASHSIG_HASH_SHIFT) & HASHSIG_HASH_MASK;
-		state = (state + ch) & HASHSIG_HASH_MASK;
+		if (len > 0) {
+			hashsig_heap_insert(&sig->mins, (hashsig_t)state);
+			hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
 
-		hashsig_heap_insert(&sig->mins, (hashsig_t)state);
-		hashsig_heap_insert(&sig->maxs, (hashsig_t)state);
-		sig->considered++;
+			sig->considered++;
 
-		prog->window[prog->win_pos] = ch;
-		prog->win_pos = (prog->win_pos + 1) % HASHSIG_HASH_WINDOW;
+			while (scan < end && (*scan == '\n' || !*scan))
+				++scan;
+		}
 	}
 
-	prog->state = state;
+	prog->use_ignores = use_ignores;
 
 	return 0;
 }
 
 static int hashsig_finalize_hashes(git_hashsig *sig)
 {
-	if (sig->mins.size < HASHSIG_HEAP_SIZE) {
+	if (sig->mins.size < HASHSIG_HEAP_MIN_SIZE) {
 		giterr_set(GITERR_INVALID,
 			"File too small for similarity signature calculation");
 		return GIT_EBUFS;
@@ -274,11 +244,13 @@ int git_hashsig_create(
 	git_hashsig_option_t opts)
 {
 	int error;
-	hashsig_in_progress prog = HASHSIG_IN_PROGRESS_INIT;
+	hashsig_in_progress prog;
 	git_hashsig *sig = hashsig_alloc(opts);
 	GITERR_CHECK_ALLOC(sig);
 
-	error = hashsig_add_hashes(sig, buf, buflen, &prog);
+	hashsig_in_progress_init(&prog, sig);
+
+	error = hashsig_add_hashes(sig, (const uint8_t *)buf, buflen, &prog);
 
 	if (!error)
 		error = hashsig_finalize_hashes(sig);
@@ -296,10 +268,10 @@ int git_hashsig_create_fromfile(
 	const char *path,
 	git_hashsig_option_t opts)
 {
-	char buf[4096];
+	uint8_t buf[0x1000];
 	ssize_t buflen = 0;
 	int error = 0, fd;
-	hashsig_in_progress prog = HASHSIG_IN_PROGRESS_INIT;
+	hashsig_in_progress prog;
 	git_hashsig *sig = hashsig_alloc(opts);
 	GITERR_CHECK_ALLOC(sig);
 
@@ -308,6 +280,8 @@ int git_hashsig_create_fromfile(
 		return fd;
 	}
 
+	hashsig_in_progress_init(&prog, sig);
+
 	while (!error) {
 		if ((buflen = p_read(fd, buf, sizeof(buf))) <= 0) {
 			if ((error = (int)buflen) < 0)
@@ -362,6 +336,12 @@ static int hashsig_heap_compare(const hashsig_heap *a, const hashsig_heap *b)
 
 int git_hashsig_compare(const git_hashsig *a, const git_hashsig *b)
 {
-	return (hashsig_heap_compare(&a->mins, &b->mins) +
-			hashsig_heap_compare(&a->maxs, &b->maxs)) / 2;
+	/* if we have fewer than the maximum number of elements, then just use
+	 * one array since the two arrays will be the same
+	 */
+	if (a->mins.size < HASHSIG_HEAP_SIZE)
+		return hashsig_heap_compare(&a->mins, &b->mins);
+	else
+		return (hashsig_heap_compare(&a->mins, &b->mins) +
+				hashsig_heap_compare(&a->maxs, &b->maxs)) / 2;
 }
diff --git a/src/index.c b/src/index.c
index 0610eb5b9..cbdd43bdc 100644
--- a/src/index.c
+++ b/src/index.c
@@ -16,6 +16,7 @@
 #include "iterator.h"
 #include "pathspec.h"
 #include "ignore.h"
+#include "blob.h"
 
 #include "git2/odb.h"
 #include "git2/oid.h"
@@ -604,42 +605,23 @@ int git_index_entry__cmp_icase(const void *a, const void *b)
 	return strcasecmp(entry_a->path, entry_b->path);
 }
 
-static int index_entry_init(git_index_entry **entry_out, git_index *index, const char *rel_path)
+static int index_entry_init(
+	git_index_entry **entry_out, git_index *index, const char *rel_path)
 {
+	int error = 0;
 	git_index_entry *entry = NULL;
 	struct stat st;
 	git_oid oid;
-	const char *workdir;
-	git_buf full_path = GIT_BUF_INIT;
-	int error;
 
 	if (INDEX_OWNER(index) == NULL)
 		return create_index_error(-1,
 			"Could not initialize index entry. "
 			"Index is not backed up by an existing repository.");
 
-	workdir = git_repository_workdir(INDEX_OWNER(index));
-
-	if (!workdir)
-		return create_index_error(GIT_EBAREREPO,
-			"Could not initialize index entry. Repository is bare");
-
-	if ((error = git_buf_joinpath(&full_path, workdir, rel_path)) < 0)
-		return error;
-
-	if ((error = git_path_lstat(full_path.ptr, &st)) < 0) {
-		git_buf_free(&full_path);
-		return error;
-	}
-
-	git_buf_free(&full_path); /* done with full path */
-
-	/* There is no need to validate the rel_path here, since it will be
-	 * immediately validated by the call to git_blob_create_fromfile.
-	 */
-
-	/* write the blob to disk and get the oid */
-	if ((error = git_blob_create_fromworkdir(&oid, INDEX_OWNER(index), rel_path)) < 0)
+	/* write the blob to disk and get the oid and stat info */
+	error = git_blob__create_from_paths(
+		&oid, &st, INDEX_OWNER(index), NULL, rel_path, 0, true);
+	if (error < 0)
 		return error;
 
 	entry = git__calloc(1, sizeof(git_index_entry));
diff --git a/src/util.h b/src/util.h
index a97c9bf39..ed9624770 100644
--- a/src/util.h
+++ b/src/util.h
@@ -294,6 +294,11 @@ GIT_INLINE(bool) git__isspace(int c)
 	return (c == ' ' || c == '\t' || c == '\n' || c == '\f' || c == '\r' || c == '\v' || c == 0x85 /* Unicode CR+LF */);
 }
 
+GIT_INLINE(bool) git__isspace_nonlf(int c)
+{
+	return (c == ' ' || c == '\t' || c == '\f' || c == '\r' || c == '\v' || c == 0x85 /* Unicode CR+LF */);
+}
+
 GIT_INLINE(bool) git__iswildcard(int c)
 {
 	return (c == '*' || c == '?' || c == '[');