[PATCH] D64160: [ARM] Favour PL/MI over GE/LT when possible

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

I wrote a very similar patch at one point, but I didn't submit it because I couldn't demonstrate any significant benefit.  Then again, I only tested it with Thumb1; maybe it's more useful for Thumb2?



================
Comment at: llvm/lib/Target/ARM/ARMISelLowering.cpp:4086
+  // simpler for other passes (like the peephole optimiser) to deal with.
+  if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(RHS.getNode())) {
+    if (RHSC->getZExtValue() == 0) {
----------------
isNullConstant


================
Comment at: llvm/lib/Target/ARM/ARMISelLowering.cpp:4730
+    if (cast<ConstantSDNode>(ARMcc)->getZExtValue() == ARMCC::PL)
+      ARMcc = DAG.getConstant(ARMCC::GE, dl, MVT::i32);
     return getCMOV(dl, VT, FalseVal, TrueVal, ARMcc, CCR, Cmp, DAG);
----------------
Do you not need to check for ARMCC::MI here?  Or do we avoid that somehow?


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  https://reviews.llvm.org/D64160/new/

https://reviews.llvm.org/D64160