[PATCH] D140302: [GlobalISel] [AArch64] Fold G_PTRTOINT(G_CONSTANT)

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D140302#4004906 <https://reviews.llvm.org/D140302#4004906>, @arsenm wrote:

> Where are these coming from? I thought we directly emitted pointer constants now?

I think this is special cased for ConstantPointerNull



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Comment at: llvm/include/llvm/Target/GlobalISel/Combine.td:470
+    [{ return Helper.matchCombineP2IToC(*${root}, ${info}); }]),
+  (apply [{ Helper.applyCombineP2IToC(*${root}, ${info}); }])
+>;
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Should be able to just use replaceInstWithConstant


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Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:2056-2059
+  assert(MI.getOpcode() == TargetOpcode::G_PTRTOINT && "Expected a G_PTRTOINT");
+  const Register SrcReg = MI.getOperand(1).getReg();
+  const MachineInstr *SrcInstr = MRI.getVRegDef(SrcReg);
+  return SrcInstr->getOpcode() == TargetOpcode::G_CONSTANT;
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We already have a matchConstantOp, but that checks for a specific constant. Should have another generic one that checks for any constant


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  https://reviews.llvm.org/D140302/new/

https://reviews.llvm.org/D140302