From: Matthieu Darbois <mayeut@users.noreply.github.com>
Date: Tue, 26 Apr 2016 20:06:06 +0000 (+0200)
Subject: Fix negative shift left reported by UBSan (#757)
X-Git-Tag: v2.1.1~18^2~27
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6f2ac3ee366a9b587abe9a72febc400ba5b98c24;p=openjpeg

Fix negative shift left reported by UBSan (#757)

This shall have no performance impact on 2’s complement machine where
the compiler replaces the multiplication by power of two (constant) by
a left shift.
Verified at least on MacOS Xcode 7.3, same assembly generated after fix.
---

diff --git a/src/lib/openjp2/t1.c b/src/lib/openjp2/t1.c
index 108ce78b..8d020bb5 100644
--- a/src/lib/openjp2/t1.c
+++ b/src/lib/openjp2/t1.c
@@ -1514,7 +1514,7 @@ OPJ_BOOL opj_t1_encode_cblks(   opj_t1_t *t1,
 						if (tccp->qmfbid == 1) {
 							for (j = 0; j < cblk_h; ++j) {
 								for (i = 0; i < cblk_w; ++i) {
-									tiledp[tileIndex] <<= T1_NMSEDEC_FRACBITS;
+									tiledp[tileIndex] *= 1 << T1_NMSEDEC_FRACBITS;
 									tileIndex++;
 								}
 								tileIndex += tileLineAdvance;