V4 JIT: teach regalloc about callee-saved registers.

Callee-saved registers won't get clobbered by a call, so any value
stored in it will survive the call.

Change-Id: I2b61b84617b01bf7ce7e81cd0119a6da689ee9d5
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/src/qml/jit/qv4regalloc.cpp b/src/qml/jit/qv4regalloc.cpp
index e21676e520..6a2f5ca640 100644
--- a/src/qml/jit/qv4regalloc.cpp
+++ b/src/qml/jit/qv4regalloc.cpp
@@ -1280,19 +1280,23 @@ void RegisterAllocator::prepareRanges()
     const int regCount = _normalRegisters.size();
     _fixedRegisterRanges.reserve(regCount);
     for (int reg = 0; reg < regCount; ++reg) {
-        LifeTimeInterval *lti = cloneFixedInterval(reg, false, ltiWithCalls);
-        _fixedRegisterRanges.append(lti);
-        if (lti->isValid())
-            _active.append(lti);
+        if (_normalRegisters.at(reg)->isCallerSaved()) {
+            LifeTimeInterval *lti = cloneFixedInterval(reg, false, ltiWithCalls);
+            _fixedRegisterRanges.append(lti);
+            if (lti->isValid())
+                _active.append(lti);
+        }
     }
 
     const int fpRegCount = _fpRegisters.size();
     _fixedFPRegisterRanges.reserve(fpRegCount);
     for (int fpReg = 0; fpReg < fpRegCount; ++fpReg) {
-        LifeTimeInterval *lti = cloneFixedInterval(fpReg, true, ltiWithCalls);
-        _fixedFPRegisterRanges.append(lti);
-        if (lti->isValid())
-            _active.append(lti);
+        if (_fpRegisters.at(fpReg)->isCallerSaved()) {
+            LifeTimeInterval *lti = cloneFixedInterval(fpReg, true, ltiWithCalls);
+            _fixedFPRegisterRanges.append(lti);
+            if (lti->isValid())
+                _active.append(lti);
+        }
     }
 }