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Tail call optimization improvements:

Browse Source 
Move platform independent code (lowering of possibly overwritten
arguments, check for tail call optimization eligibility) from
target X86ISelectionLowering.cpp to TargetLowering.h and
SelectionDAGISel.cpp.

Initial PowerPC tail call implementation:

Support ppc32 implemented and tested (passes my tests and
test-suite llvm-test).  
Support ppc64 implemented and half tested (passes my tests).
On ppc tail call optimization is performed if 
  caller and callee are fastcc
  call is a tail call (in tail call position, call followed by ret)
  no variable argument lists or byval arguments
  option -tailcallopt is enabled
Supported:
 * non pic tail calls on linux/darwin
 * module-local tail calls on linux(PIC/GOT)/darwin(PIC)
 * inter-module tail calls on darwin(PIC)
If constraints are not met a normal call will be emitted.

A test checking the argument lowering behaviour on x86-64 was added.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50477 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer
2008-04-30 09:16:33 +00:00
parent 4f06a0f6d5
commit 30e62c098b
16 changed files with 984 additions and 293 deletions
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30
include/llvm/Target/TargetLowering.h
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@@ -1033,6 +1033,36 @@ public:
return false;
}
/// CheckTailCallReturnConstraints - Check whether CALL node immediatly
/// preceeds the RET node and whether the return uses the result of the node
/// or is a void return. This function can be used by the target to determine
/// eligiblity of tail call optimization.
static bool CheckTailCallReturnConstraints(SDOperand Call, SDOperand Ret) {
unsigned NumOps = Ret.getNumOperands();
if ((NumOps == 1 &&
(Ret.getOperand(0) == SDOperand(Call.Val,1) ||
Ret.getOperand(0) == SDOperand(Call.Val,0))) ||
(NumOps > 1 &&
Ret.getOperand(0) == SDOperand(Call.Val,Call.Val->getNumValues()-1) &&
Ret.getOperand(1) == SDOperand(Call.Val,0)))
return true;
return false;
}
/// GetPossiblePreceedingTailCall - Get preceeding TailCallNodeOpCode node if
/// it exists skip possible ISD:TokenFactor.
static SDOperand GetPossiblePreceedingTailCall(SDOperand Chain,
unsigned TailCallNodeOpCode) {
if (Chain.getOpcode() == TailCallNodeOpCode) {
return Chain;
} else if (Chain.getOpcode() == ISD::TokenFactor) {
if (Chain.getNumOperands() &&
Chain.getOperand(0).getOpcode() == TailCallNodeOpCode)
return Chain.getOperand(0);
}
return Chain;
}
/// CustomPromoteOperation - This callback is invoked for operations that are
/// unsupported by the target, are registered to use 'custom' lowering, and
/// whose type needs to be promoted.