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Add some new methods for computing sign bit information.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28144 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-05-06 09:26:22 +00:00
parent f0df8824eb
commit a0d513ba75
1 changed files with 13 additions and 0 deletions
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13
include/llvm/Target/TargetLowering.h
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@ -389,6 +389,19 @@ public:
uint64_t &KnownOne,
unsigned Depth = 0) const;
/// ComputeNumSignBits - Return the number of times the sign bit of the
/// register is replicated into the other bits. We know that at least 1 bit
/// is always equal to the sign bit (itself), but other cases can give us
/// information. For example, immediately after an "SRA X, 2", we know that
/// the top 3 bits are all equal to each other, so we return 3.
unsigned ComputeNumSignBits(SDOperand Op, unsigned Depth = 0) const;
/// ComputeNumSignBitsForTargetNode - This method can be implemented by
/// targets that want to expose additional information about sign bits to the
/// DAG Combiner.
virtual unsigned ComputeNumSignBitsForTargetNode(SDOperand Op,
unsigned Depth = 0) const;
struct DAGCombinerInfo {
void *DC; // The DAG Combiner object.
bool BeforeLegalize;