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OS#13255723, OS#13255732, OS#13255734, OS#13255735, OS#13255737: A few more uninitialized locals. #3646

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Sep 6, 2017
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OS#13255723, OS#13255732, OS#13255734, OS#13255735, OS#13255737: A few more uninitialized locals. #3646

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6 changes: 5 additions & 1 deletion lib/Backend/GlobOpt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7507,7 +7507,11 @@ GlobOpt::TypeSpecializeInlineBuiltInBinary(IR::Instr **pInstr, Value *src1Val, V
if(src1Val->GetValueInfo()->IsLikelyInt() && src2Val->GetValueInfo()->IsLikelyInt())
{
// Compute resulting range info
int32 min1, max1, min2, max2, newMin, newMax;
int32 min1 = INT32_MIN;
int32 max1 = INT32_MAX;
int32 min2 = INT32_MIN;
int32 max2 = INT32_MAX;
int32 newMin, newMax;

Assert(this->DoAggressiveIntTypeSpec());
src1Val->GetValueInfo()->GetIntValMinMax(&min1, &max1, this->DoAggressiveIntTypeSpec());
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6 changes: 3 additions & 3 deletions lib/Backend/IntBounds.cpp
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Expand Up @@ -178,7 +178,7 @@ void IntBounds::SetBound(

// Aggressively merge the constant lower or upper bound of the base value, adjusted by the offset
ValueInfo const * const baseValueInfo = baseValue->GetValueInfo();
int constantBoundBase;
int constantBoundBase = 0xCCCCCCCC;
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0xCCCCCCCC [](start = 28, length = 10)

Why these value?

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I couldn't find a default that made sense for these. 0 is often a bad choice, MIN/MAX_INT were not great.

0xCCCCCCCC has a few good properties:
o Negative
o Bad pointer
o INT 3 on x86/x64
o Easy to spot in the debugger
o That's what VC uses to initialize the stack with -RTC1

const bool success =
Lower
? baseValueInfo->TryGetIntConstantLowerBound(&constantBoundBase, true)
Expand Down Expand Up @@ -342,7 +342,7 @@ bool IntBounds::IsGreaterThanOrEqualTo(const Value *const value, const int offse
Assert(value);

ValueInfo const * const valueInfo = value->GetValueInfo();
int constantBoundBase;
int constantBoundBase = INT32_MAX;
const bool success = valueInfo->TryGetIntConstantUpperBound(&constantBoundBase, true);
Assert(success);
if(IsGreaterThanOrEqualTo(constantBoundBase, offset))
Expand All @@ -360,7 +360,7 @@ bool IntBounds::IsLessThanOrEqualTo(const Value *const value, const int offset)
Assert(value);

ValueInfo const * const valueInfo = value->GetValueInfo();
int constantBoundBase;
int constantBoundBase = INT32_MIN;
const bool success = valueInfo->TryGetIntConstantLowerBound(&constantBoundBase, true);
Assert(success);
if(IsLessThanOrEqualTo(constantBoundBase, offset))
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2 changes: 1 addition & 1 deletion lib/Backend/Sym.cpp
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Expand Up @@ -572,7 +572,7 @@ StackSym::GetIntConstValue() const
{
return Js::TaggedInt::ToInt32(var);
}
int32 value;
int32 value = 0xCCCCCCCC;
const bool isInt32 = Js::JavascriptNumber::TryGetInt32Value(Js::JavascriptNumber::GetValue(var), &value);
Assert(isInt32);
return value;
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5 changes: 4 additions & 1 deletion lib/Backend/ValueInfo.cpp
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Expand Up @@ -787,7 +787,10 @@ ValueInfo::MergeLikelyIntValueInfo(JitArenaAllocator* alloc, Value *toDataVal, V

if(newValueType.IsInt())
{
int32 min1, max1, min2, max2;
int32 min1 = INT32_MIN;
int32 max1 = INT32_MAX;
int32 min2 = INT32_MIN;
int32 max2 = INT32_MAX;
toDataValueInfo->GetIntValMinMax(&min1, &max1, false);
fromDataValueInfo->GetIntValMinMax(&min2, &max2, false);
return ValueInfo::NewIntRangeValueInfo(alloc, min(min1, min2), max(max1, max2), wasNegativeZeroPreventedByBailout);
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