V4 IR: change BasicBlockSet::const_iterator to use std::find.

When the storage in the BasicBlockSet is a std::vector<bool>, the
begin() iterator and the ++operator now use std::find. Good STL
implementations have an optimized version specifically for
std::vector<bool> that is a lot faster than the iterating that was used
before. The change also makes the code more readable.

Change-Id: Ic37bac694c133c597b3d61a91b04a0b758516dc3
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 12 insertions, 20 deletions

diff --git a/src/qml/compiler/qv4ssa.cpp b/src/qml/compiler/qv4ssa.cpp
index 84232a9ebb..97114b9507 100644
--- a/src/qml/compiler/qv4ssa.cpp
+++ b/src/qml/compiler/qv4ssa.cpp
@@ -243,18 +243,13 @@ public:
                 else
                     flagIt = set.blockFlags->size();
             } else {
-                if (set.blockNumbers) {
+                if (set.blockNumbers)
                     numberIt = set.blockNumbers->begin();
-                } else {
-                    flagIt = 0;
-                    size_t eIt = set.blockFlags->size();
-                    while (flagIt != eIt) {
-                        if (set.blockFlags->operator[](flagIt))
-                            break;
-                        else
-                            ++flagIt;
-                    }
-                }
+                else
+                    flagIt = std::distance(set.blockFlags->begin(),
+                                           std::find(set.blockFlags->begin(),
+                                                     set.blockFlags->end(),
+                                                     true));
             }
         }
 
@@ -284,16 +279,13 @@ public:
 
         const_iterator &operator++()
         {
-            if (set.blockNumbers) {
+            if (set.blockNumbers)
                 ++numberIt;
-            } else {
-                size_t eIt = set.blockFlags->size();
-                while (flagIt != eIt) {
-                     ++flagIt;
-                    if (flagIt == eIt || set.blockFlags->operator[](flagIt))
-                        break;
-                }
-            }
+            else
+                flagIt = std::distance(set.blockFlags->begin(),
+                                       std::find(set.blockFlags->begin() + flagIt + 1,
+                                                 set.blockFlags->end(),
+                                                 true));
 
             return *this;
         }