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Set NumSignBits to 1 if KnownZero/KnownOne are being zero extended. In theory it

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is possible to do better if the high bit is set in either KnownZero/KnownOne, but
in practice NumSignBits is always 1 when we are zero extending because nothing
is known about that register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126465 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich 2011-02-25 01:11:01 +00:00
parent 33b554795d
commit 8fbbdca45c
1 changed files with 1 additions and 0 deletions
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lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
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@ -270,6 +270,7 @@ FunctionLoweringInfo::GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth) {
return NULL;
if (BitWidth > LOI->KnownZero.getBitWidth()) {
LOI->NumSignBits = 1;
LOI->KnownZero = LOI->KnownZero.zextOrTrunc(BitWidth);
LOI->KnownOne = LOI->KnownOne.zextOrTrunc(BitWidth);
}