commit b34c0752a9fefb132583197552793a7395b9d3ef
author Paul Wankadia <junyer@google.com> Mon Jun 20 16:50:11 2016 +1000
committer Paul Wankadia <junyer@google.com> Mon Jun 20 06:59:47 2016 +0000
tree 6ce8d380a60d79459e0ec1f6068f6c7d65c2a6f6
parent b246293a2ce5dbaf744185e0c58cabd235a473c1

Use flexible array members.

They are supported by GCC, Clang and MSVC and using them is better than
using arrays of size 1, which actually constitutes undefined behaviour!

Change-Id: I8041d71ffcf7ee6481c000a81a26c0083b726b90
Reviewed-on: https://code-review.googlesource.com/4981
Reviewed-by: Paul Wankadia <junyer@google.com>

re2/dfa.cc

diff --git a/re2/dfa.cc b/re2/dfa.cc
index e30aeaf..e33bb01 100644
--- a/re2/dfa.cc
+++ b/re2/dfa.cc
@@ -101,7 +101,7 @@
     uint flag_;         // Empty string bitfield flags in effect on the way
                         // into this state, along with kFlagMatch if this
                         // is a matching state.
-    std::atomic<State*> next_[1];    // Outgoing arrows from State,
+    std::atomic<State*> next_[];    // Outgoing arrows from State,
                         // one per input byte class
   };
 
@@ -469,7 +469,7 @@
   // Note that a state stores list heads only, so we use the program
   // list count for the upper bound, not the program size.
   int nnext = prog_->bytemap_range() + 1;  // + 1 for kByteEndText slot
-  int64 one_state = sizeof(State) + (nnext-1)*sizeof(std::atomic<State*>) +
+  int64 one_state = sizeof(State) + nnext*sizeof(std::atomic<State*>) +
                     (prog_->list_count()+nmark)*sizeof(int);
   if (state_budget_ < 20*one_state) {
     LOG(INFO) << StringPrintf("DFA out of memory: prog size %d mem %lld",
@@ -740,7 +740,7 @@
   // State*, empirically.
   const int kStateCacheOverhead = 32;
   int nnext = prog_->bytemap_range() + 1;  // + 1 for kByteEndText slot
-  int mem = sizeof(State) + (nnext-1)*sizeof(std::atomic<State*>) +
+  int mem = sizeof(State) + nnext*sizeof(std::atomic<State*>) +
             ninst*sizeof(int);
   if (mem_budget_ < mem + kStateCacheOverhead) {
     mem_budget_ = -1;

re2/onepass.cc

diff --git a/re2/onepass.cc b/re2/onepass.cc
index 1d745d4..a6e3321 100644
--- a/re2/onepass.cc
+++ b/re2/onepass.cc
@@ -131,7 +131,7 @@
 // the memory footprint.)
 struct OneState {
   uint32 matchcond;   // conditions to match right now.
-  uint32 action[1];
+  uint32 action[];
 };
 
 // The uint32 conditions in the action are a combination of
@@ -385,7 +385,7 @@
   // Limit max node count to 65000 as a conservative estimate to
   // avoid overflowing 16-bit node index in encoding.
   int maxnodes = 2 + inst_count(kInstByteRange);
-  int statesize = sizeof(OneState) + (bytemap_range_-1)*sizeof(uint32);
+  int statesize = sizeof(OneState) + bytemap_range_*sizeof(uint32);
   if (maxnodes >= 65000 || dfa_mem_ / 4 / statesize < maxnodes)
     return false;