From cbdc74b4b32af93b4724adcb4b2354bb811693ab Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Sat, 28 Aug 2021 11:55:53 +0200 Subject: [PATCH] BUG/MINOR: ebtree: remove dependency on incorrect macro for bits per long The code used to rely on BITS_PER_LONG to decide on the most efficient way to perform a 64-bit shift, but this macro is not defined (at best it's __BITS_PER_LONG) and it's likely that it's been like this since the early implementation of ebtrees designed on i386. Let's remove the test on this macro and rely on sizeof(long) instead, it also has the benefit of letting the compiler validate the two branches. This can be backported to all versions. Thanks to Ezequiel Garcia for reporting this one in issue #1369. --- include/import/eb64tree.h | 44 +++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 18 deletions(-) diff --git a/include/import/eb64tree.h b/include/import/eb64tree.h index ff2feee44..90635b7bf 100644 --- a/include/import/eb64tree.h +++ b/include/import/eb64tree.h @@ -375,17 +375,21 @@ __eb64_insert(struct eb_root *root, struct eb64_node *new) { /* walk down */ root = &old->node.branches; -#if BITS_PER_LONG >= 64 - side = (newkey >> old_node_bit) & EB_NODE_BRANCH_MASK; -#else - side = newkey; - side >>= old_node_bit; - if (old_node_bit >= 32) { - side = newkey >> 32; - side >>= old_node_bit & 0x1F; + + if (sizeof(long) >= 8) { + side = newkey >> old_node_bit; + } else { + /* note: provides the best code on low-register count archs + * such as i386. + */ + side = newkey; + side >>= old_node_bit; + if (old_node_bit >= 32) { + side = newkey >> 32; + side >>= old_node_bit & 0x1F; + } } side &= EB_NODE_BRANCH_MASK; -#endif troot = root->b[side]; } @@ -553,17 +557,21 @@ __eb64i_insert(struct eb_root *root, struct eb64_node *new) { /* walk down */ root = &old->node.branches; -#if BITS_PER_LONG >= 64 - side = (newkey >> old_node_bit) & EB_NODE_BRANCH_MASK; -#else - side = newkey; - side >>= old_node_bit; - if (old_node_bit >= 32) { - side = newkey >> 32; - side >>= old_node_bit & 0x1F; + + if (sizeof(long) >= 8) { + side = newkey >> old_node_bit; + } else { + /* note: provides the best code on low-register count archs + * such as i386. + */ + side = newkey; + side >>= old_node_bit; + if (old_node_bit >= 32) { + side = newkey >> 32; + side >>= old_node_bit & 0x1F; + } } side &= EB_NODE_BRANCH_MASK; -#endif troot = root->b[side]; }