[X86] Add a comment about the change in r234075.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234079 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Craig Topper 2015-04-04 02:31:43 +00:00
parent 8bc9aa92aa
commit 4ed0907298

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@ -1232,6 +1232,8 @@ def : Pat<(store (add (loadi64 addr:$dst), 0x00000000800000000), addr:$dst),
// with implicit zero-extension instead of a 64-bit and if the immediate has at // with implicit zero-extension instead of a 64-bit and if the immediate has at
// least 32 bits of leading zeros. If in addition the last 32 bits can be // least 32 bits of leading zeros. If in addition the last 32 bits can be
// represented with a sign extension of a 8 bit constant, use that. // represented with a sign extension of a 8 bit constant, use that.
// This can also reduce instruction size by eliminating the need for the REX
// prefix.
let AddedComplexity = 1 in // Give priority over i64immSExt8. let AddedComplexity = 1 in // Give priority over i64immSExt8.
def : Pat<(and GR64:$src, i64immZExt32SExt8:$imm), def : Pat<(and GR64:$src, i64immZExt32SExt8:$imm),