/// True if this is a varargs function that contains a musttail call.
bool HasMustTailInVarArgFunc;
+ /// True if this function contains a tail call. If so immutable objects like
+ /// function arguments are no longer so. A tail call *can* override fixed
+ /// stack objects like arguments so we can't treat them as immutable.
+ bool HasTailCall;
+
/// Not null, if shrink-wrapping found a better place for the prologue.
MachineBasicBlock *Save;
/// Not null, if shrink-wrapping found a better place for the epilogue.
HasMustTailInVarArgFunc = false;
Save = nullptr;
Restore = nullptr;
+ HasTailCall = false;
}
/// hasStackObjects - Return true if there are any stack objects in this
bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
+ /// Returns true if the function contains a tail call.
+ bool hasTailCall() const { return HasTailCall; }
+ void setHasTailCall() { HasTailCall = true; }
+
/// getMaxCallFrameSize - Return the maximum size of a call frame that must be
/// allocated for an outgoing function call. This is only available if
/// CallFrameSetup/Destroy pseudo instructions are used by the target, and
/// isImmutableObjectIndex - Returns true if the specified index corresponds
/// to an immutable object.
bool isImmutableObjectIndex(int ObjectIdx) const {
+ // Tail calling functions can clobber their function arguments.
+ if (HasTailCall)
+ return false;
assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
"Invalid Object Idx!");
return Objects[ObjectIdx+NumFixedObjects].isImmutable;