[PATCH] D92358: [AArch64][GlobalISel] Select Bcc when it's better than TB(N)Z

[Amara Emerson via Phabricator via llvm-commits]

aemerson added inline comments.


================
Comment at: llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp:1427-1428
+  MachineRegisterInfo &MRI = *MIB.getMRI();
+  assert(!MRI.getType(CompareReg).isVector() && "Expected scalar only?");
+  unsigned Width = MRI.getType(CompareReg).getSizeInBits();
+  assert(Width <= 64 && "Expected width to be at most 64?");
----------------
We can cache the getType().


================
Comment at: llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp:1508
 
-  if (!VRegAndVal || VRegAndVal->Value != 0) {
-    // If we can't select a CBZ then emit a cmp + Bcc.
-    auto Pred =
-        static_cast<CmpInst::Predicate>(CCMI->getOperand(1).getPredicate());
-    emitIntegerCompare(CCMI->getOperand(2), CCMI->getOperand(3),
-                       CCMI->getOperand(1), MIB);
-    const AArch64CC::CondCode CC = changeICMPPredToAArch64CC(Pred);
-    MIB.buildInstr(AArch64::Bcc, {}, {}).addImm(CC).addMBB(DestMBB);
-    I.eraseFromParent();
-    return true;
-  }
+  if (VRegAndVal && VRegAndVal->Value == 0 && IsEquality) {
+    if (tryOptAndIntoCompareBranch(LHSMI, VRegAndVal->Value, Pred, DestMBB,
----------------
Seems we lost the comment for this case.


================
Comment at: llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp:1516
+    auto LHSTy = MRI.getType(LHS);
+    if (!LHSTy.isVector() && LHSTy.getSizeInBits() <= 64) {
+      emitCBZ(LHS, /*IsNegative = */ Pred == CmpInst::ICMP_NE, DestMBB, MIB);
----------------
The type must be <= 64 for scalars right?


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  https://reviews.llvm.org/D92358/new/

https://reviews.llvm.org/D92358