Add in comments that explain what the indexing and the size of the arrays is about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163904 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Micah Villmow 2012-09-14 15:36:50 +00:00
parent c6a6660c62
commit d15e657690

View File

@ -496,6 +496,9 @@ public:
assert((unsigned)CC < array_lengthof(CondCodeActions) &&
(unsigned)VT.getSimpleVT().SimpleTy < sizeof(CondCodeActions[0])*4 &&
"Table isn't big enough!");
/// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 64bit
/// value and the upper 27 bits index into the second dimension of the
/// array to select what 64bit value to use.
LegalizeAction Action = (LegalizeAction)
((CondCodeActions[CC][VT.getSimpleVT().SimpleTy >> 5]
>> (2*(VT.getSimpleVT().SimpleTy & 0x1F))) & 3);
@ -1155,6 +1158,9 @@ protected:
assert(VT < MVT::LAST_VALUETYPE &&
(unsigned)CC < array_lengthof(CondCodeActions) &&
"Table isn't big enough!");
/// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 64bit
/// value and the upper 27 bits index into the second dimension of the
/// array to select what 64bit value to use.
CondCodeActions[(unsigned)CC][VT.SimpleTy >> 5]
&= ~(uint64_t(3UL) << (VT.SimpleTy & 0x1F)*2);
CondCodeActions[(unsigned)CC][VT.SimpleTy >> 5]
@ -1937,7 +1943,10 @@ private:
/// CondCodeActions - For each condition code (ISD::CondCode) keep a
/// LegalizeAction that indicates how instruction selection should
/// deal with the condition code.
uint64_t CondCodeActions[ISD::SETCC_INVALID][2];
/// Because each CC action takes up 2 bits, we need to have the array size
/// be large enough to fit all of the value types. This can be done by
/// dividing the MVT::LAST_VALUETYPE by 32 and adding one.
uint64_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE / 32) + 1];
ValueTypeActionImpl ValueTypeActions;