MDEV-21133: Alignment hints for ROW_FORMAT=COMPRESSED

page_zip_compress(), page_zip_decompress_low(), page_zip_reorganize():
Make use of memcpy_aligned() and memset_aligned(), so that some
operations can be translated more efficiently.

No difference was observed for AMD64 on GCC 9.2.1. But, such hints could
enable more efficient code on less common instruction set architectures,
such as 32-bit ARM, POWER or MIPS.

Author: dr-m

storage/innobase/page/page0zip.cc

@@ -1544,14 +1544,15 @@ page_zip_compress(
 	page_zip->n_blobs = unsigned(n_blobs);
 	/* Copy those header fields that will not be written
 	in buf_flush_init_for_writing() */
-	memcpy(page_zip->data + FIL_PAGE_PREV, page + FIL_PAGE_PREV,
-	       FIL_PAGE_LSN - FIL_PAGE_PREV);
-	memcpy(page_zip->data + FIL_PAGE_TYPE, page + FIL_PAGE_TYPE, 2);
-	memcpy(page_zip->data + FIL_PAGE_DATA, page + FIL_PAGE_DATA,
-	       PAGE_DATA - FIL_PAGE_DATA);
+	memcpy_aligned<8>(page_zip->data + FIL_PAGE_PREV, page + FIL_PAGE_PREV,
+			  FIL_PAGE_LSN - FIL_PAGE_PREV);
+	memcpy_aligned<2>(page_zip->data + FIL_PAGE_TYPE, page + FIL_PAGE_TYPE,
+			  2);
+	memcpy_aligned<2>(page_zip->data + FIL_PAGE_DATA, page + FIL_PAGE_DATA,
+			  PAGE_DATA - FIL_PAGE_DATA);
 	/* Copy the rest of the compressed page */
-	memcpy(page_zip->data + PAGE_DATA, buf,
-	       page_zip_get_size(page_zip) - PAGE_DATA);
+	memcpy_aligned<2>(page_zip->data + PAGE_DATA, buf,
+			  page_zip_get_size(page_zip) - PAGE_DATA);
 	mem_heap_free(heap);
 #ifdef UNIV_ZIP_DEBUG
 	ut_a(page_zip_validate(page_zip, page, index));
@@ -3021,7 +3022,7 @@ page_zip_decompress_low(
 
 	if (all) {
 		/* Copy the page header. */
-		memcpy(page, page_zip->data, PAGE_DATA);
+		memcpy_aligned<2>(page, page_zip->data, PAGE_DATA);
 	} else {
 		/* Check that the bytes that we skip are identical. */
 #if defined UNIV_DEBUG || defined UNIV_ZIP_DEBUG
@@ -3034,9 +3035,10 @@ page_zip_decompress_low(
 #endif /* UNIV_DEBUG || UNIV_ZIP_DEBUG */
 
 		/* Copy the mutable parts of the page header. */
-		memcpy(page, page_zip->data, FIL_PAGE_TYPE);
-		memcpy(PAGE_HEADER + page, PAGE_HEADER + page_zip->data,
-		       PAGE_LEVEL - PAGE_N_DIR_SLOTS);
+		memcpy_aligned<8>(page, page_zip->data, FIL_PAGE_TYPE);
+		memcpy_aligned<2>(PAGE_HEADER + page,
+				  PAGE_HEADER + page_zip->data,
+				  PAGE_LEVEL - PAGE_N_DIR_SLOTS);
 
 #if defined UNIV_DEBUG || defined UNIV_ZIP_DEBUG
 		/* Check that the page headers match after copying. */
@@ -3070,8 +3072,9 @@ page_zip_decompress_low(
 				      & PAGE_ZIP_DIR_SLOT_MASK);
 	}
 	memcpy(page + PAGE_NEW_INFIMUM, infimum_data, sizeof infimum_data);
-	memcpy(page + (PAGE_NEW_SUPREMUM - REC_N_NEW_EXTRA_BYTES + 1),
-	       supremum_extra_data, sizeof supremum_extra_data);
+	memcpy_aligned<4>(PAGE_NEW_SUPREMUM - REC_N_NEW_EXTRA_BYTES + 1
+			  + page, supremum_extra_data,
+			  sizeof supremum_extra_data);
 
 	page_zip_set_alloc(&d_stream, heap);
 
@@ -4737,8 +4740,8 @@ page_zip_reorganize(
 					index, mtr);
 
 	/* Copy the PAGE_MAX_TRX_ID or PAGE_ROOT_AUTO_INC. */
-	memcpy(page + (PAGE_HEADER + PAGE_MAX_TRX_ID),
-	       temp_page + (PAGE_HEADER + PAGE_MAX_TRX_ID), 8);
+	memcpy_aligned<8>(page + (PAGE_HEADER + PAGE_MAX_TRX_ID),
+			  temp_page + (PAGE_HEADER + PAGE_MAX_TRX_ID), 8);
 	/* PAGE_MAX_TRX_ID must be set on secondary index leaf pages. */
 	ut_ad(dict_index_is_clust(index) || !page_is_leaf(temp_page)
 	      || page_get_max_trx_id(page) != 0);
@@ -4806,21 +4809,24 @@ page_zip_copy_recs(
 	PAGE_MAX_TRX_ID.  Skip the rest of the page header and
 	trailer.  On the compressed page, there is no trailer. */
 	compile_time_assert(PAGE_MAX_TRX_ID + 8 == PAGE_HEADER_PRIV_END);
-	memcpy(PAGE_HEADER + page, PAGE_HEADER + src,
-	       PAGE_HEADER_PRIV_END);
-	memcpy(PAGE_DATA + page, PAGE_DATA + src,
-	       srv_page_size - PAGE_DATA - FIL_PAGE_DATA_END);
-	memcpy(PAGE_HEADER + page_zip->data, PAGE_HEADER + src_zip->data,
-	       PAGE_HEADER_PRIV_END);
-	memcpy(PAGE_DATA + page_zip->data, PAGE_DATA + src_zip->data,
-	       page_zip_get_size(page_zip) - PAGE_DATA);
+	memcpy_aligned<2>(PAGE_HEADER + page, PAGE_HEADER + src,
+			  PAGE_HEADER_PRIV_END);
+	memcpy_aligned<2>(PAGE_DATA + page, PAGE_DATA + src,
+			  srv_page_size - (PAGE_DATA + FIL_PAGE_DATA_END));
+	memcpy_aligned<2>(PAGE_HEADER + page_zip->data,
+			  PAGE_HEADER + src_zip->data,
+			  PAGE_HEADER_PRIV_END);
+	memcpy_aligned<2>(PAGE_DATA + page_zip->data,
+			  PAGE_DATA + src_zip->data,
+			  page_zip_get_size(page_zip) - PAGE_DATA);
 
 	if (dict_index_is_clust(index)) {
 		/* Reset the PAGE_ROOT_AUTO_INC field when copying
 		from a root page. */
-		memset(PAGE_HEADER + PAGE_ROOT_AUTO_INC + page, 0, 8);
-		memset(PAGE_HEADER + PAGE_ROOT_AUTO_INC + page_zip->data,
-		       0, 8);
+		memset_aligned<8>(PAGE_HEADER + PAGE_ROOT_AUTO_INC
+				  + page, 0, 8);
+		memset_aligned<8>(PAGE_HEADER + PAGE_ROOT_AUTO_INC
+				  + page_zip->data, 0, 8);
 	} else {
 		/* The PAGE_MAX_TRX_ID must be nonzero on leaf pages
 		of secondary indexes, and 0 on others. */