[llvm] [GlobalIsel] Combine logic of icmps (PR #77855)

[Matt Arsenault via llvm-commits]

Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/77855 at github.com>


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@@ -6643,3 +6644,178 @@ bool CombinerHelper::matchSelect(MachineInstr &MI, BuildFnTy &MatchInfo) {
 
   return false;
 }
+
+/// Fold (icmp Pred1 V1, C1) && (icmp Pred2 V2, C2)
+/// or   (icmp Pred1 V1, C1) || (icmp Pred2 V2, C2)
+/// into a single comparison using range-based reasoning.
+/// see InstCombinerImpl::foldAndOrOfICmpsUsingRanges.
+bool CombinerHelper::tryFoldAndOrOrICmpsUsingRanges(GLogicalBinOp *Logic,
+                                                    BuildFnTy &MatchInfo) {
+  assert(Logic->getOpcode() != TargetOpcode::G_XOR && "unexpected xor");
+  bool IsAnd = Logic->getOpcode() == TargetOpcode::G_AND;
+  Register DstReg = Logic->getReg(0);
+  Register LHS = Logic->getLHSReg();
+  Register RHS = Logic->getRHSReg();
+  unsigned Flags = Logic->getFlags();
+
+  // We need an G_ICMP on the LHS register.
+  GICmp *Cmp1 = getOpcodeDef<GICmp>(LHS, MRI);
+  if (!Cmp1)
+    return false;
+
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arsenm wrote:

Should there be hasOneUse checks here?

https://github.com/llvm/llvm-project/pull/77855