Avoid unnecessary saving of the instruction pointer in the JIT

We only need to save it when the line number changes, not for each and every
call.

Change-Id: I1a6fdf97abd3dd654bbd97d2a99cd09e9c20f64f
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 7 insertions, 4 deletions

diff --git a/src/qml/compiler/qv4isel_masm.cpp b/src/qml/compiler/qv4isel_masm.cpp
index 4eeab0f184..0b372fec03 100644
--- a/src/qml/compiler/qv4isel_masm.cpp
+++ b/src/qml/compiler/qv4isel_masm.cpp
@@ -697,14 +697,20 @@ void InstructionSelection::run(int functionIndex)
     _as->addPtr(Assembler::TrustedImm32(sizeof(QV4::SafeValue)*locals), Assembler::LocalsRegister);
     _as->storePtr(Assembler::LocalsRegister, Address(Assembler::ScratchRegister, qOffsetOf(ExecutionEngine, jsStackTop)));
 
+    int lastLine = -1;
     for (int i = 0, ei = _function->basicBlocks.size(); i != ei; ++i) {
         V4IR::BasicBlock *nextBlock = (i < ei - 1) ? _function->basicBlocks[i + 1] : 0;
         _block = _function->basicBlocks[i];
         _as->registerBlock(_block, nextBlock);
 
         foreach (V4IR::Stmt *s, _block->statements) {
-            if (s->location.isValid())
+            if (s->location.isValid()) {
                 _as->recordLineNumber(s->location.startLine);
+                if (s->location.startLine != lastLine) {
+                    _as->saveInstructionPointer(Assembler::ScratchRegister);
+                    lastLine = s->location.startLine;
+                }
+            }
             s->accept(this);
         }
     }
diff --git a/src/qml/compiler/qv4isel_masm_p.h b/src/qml/compiler/qv4isel_masm_p.h
index 37e99bd359..b55192aae7 100644
--- a/src/qml/compiler/qv4isel_masm_p.h
+++ b/src/qml/compiler/qv4isel_masm_p.h
@@ -468,7 +468,6 @@ public:
     }
 
     void callAbsolute(const char* functionName, FunctionPtr function) {
-        saveInstructionPointer(ScratchRegister);
         CallToLink ctl;
         ctl.call = call();
         ctl.externalFunction = function;
@@ -477,13 +476,11 @@ public:
     }
 
     void callAbsolute(const char* /*functionName*/, Address addr) {
-        saveInstructionPointer(ScratchRegister);
         call(addr);
     }
 
     void callAbsolute(const char* /*functionName*/, const RelativeCall &relativeCall)
     {
-        saveInstructionPointer(ScratchRegister);
         call(relativeCall.addr);
     }