[RISCV][GlobalISel] Generate direct branch selection

2 files changed, 10 insertions, 13 deletions

diff --git a/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index cde2c8d..89b6ecd 100644
--- a/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
+++ b/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
@@ -364,7 +364,6 @@ public:
     case GenericOpcode::G_FPEXTLOAD:
     case GenericOpcode::G_FPTRUNCSTORE:
     case GenericOpcode::G_STORE:
-    case GenericOpcode::G_BR:
     case GenericOpcode::G_BRCOND:
       return {};
     case GenericOpcode::G_FCONSTANT: {
@@ -441,8 +440,6 @@ public:
       return selectStore(Instruction, Function);
     case GenericOpcode::G_FPTRUNCSTORE:
       return selectFloatTruncStore(Instruction, Function, Target);
-    case GenericOpcode::G_BR:
-      return selectBranch(Instruction);
     case GenericOpcode::G_BRCOND:
       return selectConditionalBranch(Instruction);
     case GenericOpcode::G_CONSTANT:
@@ -1425,16 +1422,6 @@ private:
     return makeUnexpected(ErrorCode::Unsupported, "RISC-V cannot select this generic store type");
   }
 
-  [[nodiscard]] Expected<void> selectBranch(MachineInstr &Instruction) const {
-    auto Zero = physicalRegister(PhysicalRegisterID::X0);
-    if (!Zero)
-      return std::unexpected(Zero.error());
-    auto Inserted = insertPhysicalRegister(Instruction, 0, *Zero, RegisterOperandFlag::Define);
-    if (!Inserted)
-      return std::unexpected(Inserted.error());
-    return Instruction.setOpcode(instructionOpcode(InstructionOpcode::JAL));
-  }
-
   [[nodiscard]] Expected<void> selectConditionalBranch(MachineInstr &Instruction) const {
     auto Zero = physicalRegister(PhysicalRegisterID::X0);
     if (!Zero)
diff --git a/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc b/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
index f40e5d4..6ba88ef 100644
--- a/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
+++ b/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
@@ -1,5 +1,15 @@
 selection_rules:
   -
+    id: select_g_br
+    priority: 100
+    match:
+      opcode: G_BR
+    apply:
+      instructions:
+        - opcode: PseudoBR
+          root: true
+          operands: [{ operand: 0 }]
+  -
     id: select_g_implicit_def
     priority: 100
     match: