RegExp: Do on demand JIT compilation

JIT compiling means that we need to obtain executable memory for the
jitted code. That has a non-neglibile cost (in addition to the runtime
cost of compiling the pattern).

Thus, only compile the pattern if we suspect it to be worthwhile:
- when we called match multiple times
- or when the string we match against is quite large

We also assume that the JIT generally works, and thus discard the
bytecode immediately after jitting – if the JIT fails once (either to
compile, or with offset failure), we recompile the bytecode and never
JIT again.

Change-Id: I91e9e10c5ab895af730dbb4a9bc85470dd794d1f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/qml/jsruntime/qv4regexp_p.h b/src/qml/jsruntime/qv4regexp_p.h
index 1b70354caa..8a178dd2f6 100644
--- a/src/qml/jsruntime/qv4regexp_p.h
+++ b/src/qml/jsruntime/qv4regexp_p.h
@@ -66,6 +66,8 @@ struct RegExp : Base {
     int subPatternCount;
     uint flags;
     bool valid;
+    bool jitFailed;
+    quint8 matchCount;
 
     QString flagsAsString() const;
     int captureCount() const { return subPatternCount + 1; }