llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-03-06 20:33:54 +00:00

History

Bob Wilson 67ba22318b Fix a minor bug in DAGCombiner's folding of SELECT. Folding "select C, 0, 1"

to "C ^ 1" is only valid when C is known to be either 0 or 1.  Most of the
similar foldings in this function only handle "i1" types, but this one appears
intentionally written to handle larger integer types.  If C has an integer
type larger than "i1", this needs to check if the high bits of a boolean
are known to be zero.  I also changed the comment to describe this folding as
"C ^ 1" instead of "~C", since that is what the code does and since the latter
would only be valid for "i1" types.  The good news is that most LLVM targets
use TargetLowering::ZeroOrOneBooleanContent so this change will not disable
the optimization; the bad news is that I've been unable to come up with a
testcase to demonstrate the problem.

I have also removed a "FIXME" comment for folding "select C, X, 0" to "C & X",
since the code looks correct to me.  It could be made more aggressive by not
limiting the type to "i1", but that would then require checking for
TargetLowering::ZeroOrNegativeOneBooleanContent.  Similar changes could be
done for the other SELECT foldings, but it was decided to be not worth the
trouble and complexity (see e.g., r44663).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62790 91177308-0d34-0410-b5e6-96231b3b80d8

2009-01-22 22:05:48 +00:00

CallingConvLower.cpp

…

CMakeLists.txt

Experimental post-pass scheduling support. Post-pass scheduling

2008-11-19 23:18:57 +00:00

DAGCombiner.cpp

Fix a minor bug in DAGCombiner's folding of SELECT. Folding "select C, 0, 1"

2009-01-22 22:05:48 +00:00

FastISel.cpp

Eliminate a couple of fields from TargetRegisterClass: SubRegClasses and SuperRegClasses. These are not necessary. Also eliminate getSubRegisterRegClass and getSuperRegisterRegClass. These are slow and their results can change if register file names change. Just use TargetLowering::getRegClassFor() to get the right TargetRegisterClass instead.

2009-01-22 09:10:11 +00:00