[GlobalISel] Add G_STEP_VECTOR instruction (#115598)

aka llvm.stepvector Intrinsic

2 files changed, 41 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
index 02dbe78..c5e5c92 100644
--- a/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -809,6 +809,17 @@ MachineInstrBuilder MachineIRBuilder::buildInsert(const DstOp &Res,
   return buildInstr(TargetOpcode::G_INSERT, Res, {Src, Op, uint64_t(Index)});
 }
 
+MachineInstrBuilder MachineIRBuilder::buildStepVector(const DstOp &Res,
+                                                      unsigned Step) {
+  ConstantInt *CI =
+      ConstantInt::get(getMF().getFunction().getContext(), APInt(64, Step));
+  auto StepVector = buildInstr(TargetOpcode::G_STEP_VECTOR);
+  StepVector->setDebugLoc(DebugLoc());
+  Res.addDefToMIB(*getMRI(), StepVector);
+  StepVector.addCImm(CI);
+  return StepVector;
+}
+
 MachineInstrBuilder MachineIRBuilder::buildVScale(const DstOp &Res,
                                                   unsigned MinElts) {
 
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index 10369928..3910046 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1731,6 +1731,36 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     }
     break;
   }
+  case TargetOpcode::G_STEP_VECTOR: {
+    if (!MI->getOperand(1).isCImm()) {
+      report("operand must be cimm", MI);
+      break;
+    }
+
+    if (!MI->getOperand(1).getCImm()->getValue().isStrictlyPositive()) {
+      report("step must be > 0", MI);
+      break;
+    }
+
+    LLT DstTy = MRI->getType(MI->getOperand(0).getReg());
+    if (!DstTy.isScalableVector()) {
+      report("Destination type must be a scalable vector", MI);
+      break;
+    }
+
+    // <vscale x 2 x p0>
+    if (!DstTy.getElementType().isScalar()) {
+      report("Destination element type must be scalar", MI);
+      break;
+    }
+
+    if (MI->getOperand(1).getCImm()->getBitWidth() !=
+        DstTy.getElementType().getScalarSizeInBits()) {
+      report("step bitwidth differs from result type element bitwidth", MI);
+      break;
+    }
+    break;
+  }
   case TargetOpcode::G_INSERT_SUBVECTOR: {
     const MachineOperand &Src0Op = MI->getOperand(1);
     if (!Src0Op.isReg()) {