From 8d0d1b11e381130dec12f46b959c3107c3f47160 Mon Sep 17 00:00:00 2001 From: Erik Verbruggen Date: Thu, 6 Apr 2017 15:42:51 +0200 Subject: V4: Fix issues with very small loops Loops consisting of just a single basic block (e.g. a do-while loop with no nested loops or if statements) have a back-edge to themselves. There were 2 problems: - loop detection would create LoopInfo for any loop header referred to by blocks inside the loop (and a 1 block loop doesn't have body blocks), nor would it mark the loop header as such - when splitting critical edges, the newly inserted block would not be marked as part of the loop This is a problem specifically for 1 block loops: the block ends with a CJUMP, so the back-edge is a critical edge. So the new block inserted by edge splitting wouldn't be marked as belonging to the loop. The end result was that the life-time intervals for temporaries that are defined before the loop, but that are used inside the loop, and not after the loop, would have their life-time ended before the loop ends (instead of spanning the whole loop, *including* the back-edge). This in turns could lead to the stack/register allocator re-using the storage for that temporary, resulting in strange things happening. Task-number: QTBUG-59012 Change-Id: Ic946c73913711272efea2151cb85350412ca2fde Reviewed-by: Simon Hausmann --- src/qml/compiler/qv4jsir.cpp | 4 ---- 1 file changed, 4 deletions(-) (limited to 'src/qml/compiler/qv4jsir.cpp') diff --git a/src/qml/compiler/qv4jsir.cpp b/src/qml/compiler/qv4jsir.cpp index 5687834b00..1dff7c9ac3 100644 --- a/src/qml/compiler/qv4jsir.cpp +++ b/src/qml/compiler/qv4jsir.cpp @@ -448,10 +448,6 @@ void Function::setScheduledBlocks(const QVector &scheduled) Q_ASSERT(!_allBasicBlocks); _allBasicBlocks = new QVector(basicBlocks()); _basicBlocks = scheduled; -} - -void Function::renumberBasicBlocks() -{ for (int i = 0, ei = basicBlockCount(); i != ei; ++i) basicBlock(i)->changeIndex(i); } -- cgit v1.2.3