commit 849fcca09004751b0fc9a2a93fd9eb985a4c6876
author Tim Northover <tnorthover@apple.com> Tue Jun 27 21:41:40 2017 +0000
committer Tim Northover <tnorthover@apple.com> Tue Jun 27 21:41:40 2017 +0000
tree 1c0dfa1c5148e8e03cb63e5466e4d629f5226db2
parent ad3d174674539d05a7710aad59d5ed0308bfe13f

GlobalISel: verify that a COPY is trivial when created.

Without this check, COPY instructions can actually be one of the generic casts
in disguise. That's confusing and bad.

At some point during ISel this restriction has to be relaxed since the fully
selected instructions will usually use COPY for those purposes. Right now I
think it's possible that relaxation occurs during RegBankSelect (hence the
change there). I'm not convinced that's where it belongs long-term though.

llvm-svn: 306470

llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 6fcc390..ff3e53a 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -268,6 +268,8 @@
 }
 
 MachineInstrBuilder MachineIRBuilder::buildCopy(unsigned Res, unsigned Op) {
+  assert(MRI->getType(Res) == LLT() || MRI->getType(Op) == LLT() ||
+         MRI->getType(Res) == MRI->getType(Op));
   return buildInstr(TargetOpcode::COPY).addDef(Res).addUse(Op);
 }
 
@@ -384,7 +386,6 @@
   return buildInstr(Opcode).addDef(Res).addUse(Op);
 }
 
-
 MachineInstrBuilder MachineIRBuilder::buildCast(unsigned Dst, unsigned Src) {
   LLT SrcTy = MRI->getType(Src);
   LLT DstTy = MRI->getType(Dst);
@@ -483,7 +484,7 @@
 #endif
 
   if (Ops.size() == 1)
-    return buildCopy(Res, Ops[0]);
+    return buildCast(Res, Ops[0]);
 
   MachineInstrBuilder MIB = buildInstr(TargetOpcode::G_MERGE_VALUES);
   MIB.addDef(Res);