[llvm] [GlobalIsel][AArch64] Select G_SCMP and G_UCMP (PR #99820)

[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/99820 at github.com>


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@@ -7269,6 +7272,36 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerMinMax(MachineInstr &MI) {
   return Legalized;
 }
 
+LegalizerHelper::LegalizeResult
+LegalizerHelper::lowerThreewayCompare(MachineInstr &MI) {
+  GSUCmp *Cmp = cast<GSUCmp>(&MI);
+
+  Register Dst = Cmp->getReg(0);
+  LLT DstTy = MRI.getType(Dst);
+  LLT CmpTy = DstTy.changeElementSize(1);
+
+  CmpInst::Predicate LTPredicate = Cmp->isSigned()
+                                       ? CmpInst::Predicate::ICMP_SLT
+                                       : CmpInst::Predicate::ICMP_ULT;
+  CmpInst::Predicate GTPredicate = Cmp->isSigned()
+                                       ? CmpInst::Predicate::ICMP_SGT
+                                       : CmpInst::Predicate::ICMP_UGT;
+
+  auto One = MIRBuilder.buildConstant(DstTy, 1);
+  auto Zero = MIRBuilder.buildConstant(DstTy, 0);
+  auto MinusOne = MIRBuilder.buildConstant(DstTy, -1);
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arsenm wrote:

Sink these down to just before first use? 

https://github.com/llvm/llvm-project/pull/99820