GlobalISel: teach legalizer how to handle integer constants.

llvm-svn: 279340

2 files changed, 12 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/MachineLegalizeHelper.cpp b/llvm/lib/CodeGen/GlobalISel/MachineLegalizeHelper.cpp
index 29fdee8633f..632d6292f9c 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineLegalizeHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineLegalizeHelper.cpp
@@ -104,6 +104,7 @@ MachineLegalizeHelper::narrowScalar(MachineInstr &MI, LLT NarrowTy) {
 
 MachineLegalizeHelper::LegalizeResult
 MachineLegalizeHelper::widenScalar(MachineInstr &MI, LLT WideTy) {
+  unsigned WideSize = WideTy.getSizeInBits();
   switch (MI.getOpcode()) {
   default:
     return UnableToLegalize;
@@ -116,7 +117,6 @@ MachineLegalizeHelper::widenScalar(MachineInstr &MI, LLT WideTy) {
     // Perform operation at larger width (any extension is fine here, high bits
     // don't affect the result) and then truncate the result back to the
     // original type.
-    unsigned WideSize = WideTy.getSizeInBits();
 
     MIRBuilder.setInstr(MI);
 
@@ -133,6 +133,14 @@ MachineLegalizeHelper::widenScalar(MachineInstr &MI, LLT WideTy) {
     MI.eraseFromParent();
     return Legalized;
   }
+  case TargetOpcode::G_CONSTANT: {
+    MIRBuilder.setInstr(MI);
+    unsigned DstExt = MRI.createGenericVirtualRegister(WideSize);
+    MIRBuilder.buildConstant(WideTy, DstExt, MI.getOperand(1).getImm());
+    MIRBuilder.buildTrunc(MI.getType(), MI.getOperand(0).getReg(), DstExt);
+    MI.eraseFromParent();
+    return Legalized;
+  }
   }
 }
 
diff --git a/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp b/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
index 881b5026fa6..fa23627de7c 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineLegalizer.cpp
@@ -119,8 +119,9 @@ LLT MachineLegalizer::findLegalType(unsigned Opcode, LLT Ty,
                          [&](LLT Ty) -> LLT { return Ty.halfScalarSize(); });
   }
   case WidenScalar: {
-    return findLegalType(Opcode, Ty,
-                         [&](LLT Ty) -> LLT { return Ty.doubleScalarSize(); });
+    return findLegalType(Opcode, Ty, [&](LLT Ty) -> LLT {
+      return Ty.getSizeInBits() < 8 ? LLT::scalar(8) : Ty.doubleScalarSize();
+    });
   }
   case FewerElements: {
     return findLegalType(Opcode, Ty,