[PATCH] D36084: [globalisel][tablegen] Support zero-instruction emission.

[Daniel Sanders via Phabricator via llvm-commits]

dsanders updated this revision to Diff 108909.
dsanders added a comment.
Herald added a subscriber: javed.absar.

In https://reviews.llvm.org/D36084#825975, @dsanders wrote:

> I had a testcase for this one but it seems to have gone missing. I'll update with one shortly


It looks like it disappeared during a rebase and is already committed. That
being the case, I've just removed the C++ implementation of bitcast and
int_to_ptr that are covered by imported rules.


https://reviews.llvm.org/D36084

Files:
  lib/Target/AArch64/AArch64InstructionSelector.cpp
  utils/TableGen/GlobalISelEmitter.cpp


Index: utils/TableGen/GlobalISelEmitter.cpp
===================================================================
--- utils/TableGen/GlobalISelEmitter.cpp
+++ utils/TableGen/GlobalISelEmitter.cpp
@@ -2270,6 +2270,7 @@
       auto &DstMIBuilder = M.addAction<BuildMIAction>(0, &DstI, InsnMatcher);
       DstMIBuilder.addRenderer<CopyRenderer>(0, InsnMatcher, DstIOperand.Name);
       DstMIBuilder.addRenderer<CopyRenderer>(0, InsnMatcher, Dst->getName());
+      M.addAction<ConstrainOperandToRegClassAction>(0, 0, RC);
 
       // We're done with this pattern!  It's eligible for GISel emission; return
       // it.
Index: lib/Target/AArch64/AArch64InstructionSelector.cpp
===================================================================
--- lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -1165,8 +1165,18 @@
 
 
   case TargetOpcode::G_INTTOPTR:
+    // Imported SelectionDAG rules can handle everything except pointer types
+    // which didn't exist in that instruction selector.
+    if (MRI.getType(I.getOperand(0).getReg()).isPointer() ||
+        MRI.getType(I.getOperand(1).getReg()).isPointer())
+      return selectCopy(I, TII, MRI, TRI, RBI);
   case TargetOpcode::G_BITCAST:
-    return selectCopy(I, TII, MRI, TRI, RBI);
+    // Imported SelectionDAG rules can handle every bitcast except those that
+    // bitcast from a type to the same type. Ideally, these shouldn't occur
+    // but we might not run an optimizer that deletes them.
+    if (MRI.getType(I.getOperand(0).getReg()) ==
+        MRI.getType(I.getOperand(1).getReg()))
+      return selectCopy(I, TII, MRI, TRI, RBI);
 
   case TargetOpcode::G_FPEXT: {
     if (MRI.getType(I.getOperand(0).getReg()) != LLT::scalar(64)) {


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