GlobalISel: restrict G_EXTRACT instruction to just one operand.

A bit more painful than G_INSERT because it was more widely used, but this
should simplify the handling of extract operations in most locations.

llvm-svn: 297100

3 files changed, 17 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 6c403a8212a..0470b3af7f5 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -341,7 +341,7 @@ bool IRTranslator::translateExtractValue(const User &U,
   uint64_t Offset = 8 * DL->getIndexedOffsetInType(Src->getType(), Indices);
 
   unsigned Res = getOrCreateVReg(U);
-  MIRBuilder.buildExtract(Res, Offset, getOrCreateVReg(*Src));
+  MIRBuilder.buildExtract(Res, getOrCreateVReg(*Src), Offset);
 
   return true;
 }
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index a8bc694dc17..d1f31607401 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -202,8 +202,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
       if (OpSegSize != OpSize) {
         // A genuine extract is needed.
         OpSegReg = MRI.createGenericVirtualRegister(LLT::scalar(OpSegSize));
-        MIRBuilder.buildExtract(OpSegReg, std::max(OpSegStart, (int64_t)0),
-                                OpReg);
+        MIRBuilder.buildExtract(OpSegReg, OpReg,
+                                std::max(OpSegStart, (int64_t)0));
       }
 
       unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 1b7c7a6e52b..3614333037c 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -382,34 +382,25 @@ MachineInstrBuilder MachineIRBuilder::buildCast(unsigned Dst, unsigned Src) {
   return buildInstr(Opcode).addDef(Dst).addUse(Src);
 }
 
-MachineInstrBuilder MachineIRBuilder::buildExtract(ArrayRef<unsigned> Results,
-                                                   ArrayRef<uint64_t> Indices,
-                                                   unsigned Src) {
+MachineInstrBuilder MachineIRBuilder::buildExtract(unsigned Res, unsigned Src,
+                                                   uint64_t Index) {
 #ifndef NDEBUG
-  assert(Results.size() == Indices.size() && "inconsistent number of regs");
-  assert(!Results.empty() && "invalid trivial extract");
-  assert(std::is_sorted(Indices.begin(), Indices.end()) &&
-         "extract offsets must be in ascending order");
-
   assert(MRI->getType(Src).isValid() && "invalid operand type");
-  for (auto Res : Results)
-    assert(MRI->getType(Res).isValid() && "invalid operand type");
+  assert(MRI->getType(Res).isValid() && "invalid operand type");
+  assert(Index + MRI->getType(Res).getSizeInBits() <=
+             MRI->getType(Src).getSizeInBits() &&
+         "extracting off end of register");
 #endif
 
-  auto MIB = BuildMI(getMF(), DL, getTII().get(TargetOpcode::G_EXTRACT));
-  for (auto Res : Results)
-    MIB.addDef(Res);
-
-  MIB.addUse(Src);
-
-  for (auto Idx : Indices)
-    MIB.addImm(Idx);
-
-  getMBB().insert(getInsertPt(), MIB);
-  if (InsertedInstr)
-    InsertedInstr(MIB);
+  if (MRI->getType(Res).getSizeInBits() == MRI->getType(Src).getSizeInBits()) {
+    assert(Index == 0 && "insertion past the end of a register");
+    return buildCast(Res, Src);
+  }
 
-  return MIB;
+  return buildInstr(TargetOpcode::G_EXTRACT)
+      .addDef(Res)
+      .addUse(Src)
+      .addImm(Index);
 }
 
 MachineInstrBuilder