[PATCH] D14496: X86: More efficient codegen for 64-bit compares on 32-bit target

[David Kreitzer via llvm-commits]

DavidKreitzer added inline comments.

================
Comment at: lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp:2748
@@ +2747,3 @@
+
+  if (TLI.getOperationAction(ISD::SETCC_PARTS, LHSLo.getValueType()) ==
+      TargetLowering::Custom) {
----------------
Another advantage of the SETCCE approach is that it can be used to implement arbitrary precision integer compares.  For example, an __int128 compare on x86 could be legalized to

SUBC
SUBE
SUBE
SETCCE



http://reviews.llvm.org/D14496