GlobalISel: Add another overload of buildUnmerge

It's annoying to have to create an array of the result type,
particularly when you don't care about the size of the value.

llvm-svn: 357763

Author: arsenm

llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

@@ -731,6 +731,9 @@ class MachineIRBuilder {
   MachineInstrBuilder buildUnmerge(ArrayRef<LLT> Res, const SrcOp &Op);
   MachineInstrBuilder buildUnmerge(ArrayRef<unsigned> Res, const SrcOp &Op);
 
+  /// Build and insert an unmerge of \p Res sized pieces to cover \p Op
+  MachineInstrBuilder buildUnmerge(LLT Res, const SrcOp &Op);
+
   /// Build and insert \p Res = G_BUILD_VECTOR \p Op0, ...
   ///
   /// G_BUILD_VECTOR creates a vector value from multiple scalar registers.

llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

@@ -547,6 +547,15 @@ MachineInstrBuilder MachineIRBuilder::buildUnmerge(ArrayRef<LLT> Res,
   return buildInstr(TargetOpcode::G_UNMERGE_VALUES, TmpVec, Op);
 }
 
+MachineInstrBuilder MachineIRBuilder::buildUnmerge(LLT Res,
+                                                   const SrcOp &Op) {
+  unsigned NumReg = Op.getLLTTy(*getMRI()).getSizeInBits() / Res.getSizeInBits();
+  SmallVector<unsigned, 8> TmpVec;
+  for (unsigned I = 0; I != NumReg; ++I)
+    TmpVec.push_back(getMRI()->createGenericVirtualRegister(Res));
+  return buildUnmerge(TmpVec, Op);
+}
+
 MachineInstrBuilder MachineIRBuilder::buildUnmerge(ArrayRef<unsigned> Res,
                                                    const SrcOp &Op) {
   // Unfortunately to convert from ArrayRef<unsigned> to ArrayRef<DstOp>,

llvm/unittests/CodeGen/GlobalISel/MachineIRBuilderTest.cpp

@@ -90,3 +90,23 @@ TEST_F(GISelMITest, DstOpSrcOp) {
 
   EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
 }
+
+TEST_F(GISelMITest, BuildUnmerge) {
+  if (!TM)
+    return;
+
+  SmallVector<unsigned, 4> Copies;
+  collectCopies(Copies, MF);
+  B.buildUnmerge(LLT::scalar(32), Copies[0]);
+  B.buildUnmerge(LLT::scalar(16), Copies[1]);
+
+  auto CheckStr = R"(
+  ; CHECK: [[COPY0:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK: [[COPY1:%[0-9]+]]:_(s64) = COPY $x1
+  ; CHECK: [[UNMERGE32_0:%[0-9]+]]:_(s32), [[UNMERGE32_1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY0]]
+  ; CHECK: [[UNMERGE16_0:%[0-9]+]]:_(s16), [[UNMERGE16_1:%[0-9]+]]:_(s16), [[UNMERGE16_2:%[0-9]+]]:_(s16), [[UNMERGE16_3:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[COPY1]]
+
+  )";
+
+  EXPECT_TRUE(CheckMachineFunction(*MF, CheckStr)) << *MF;
+}