[RISCV][GlobalISel] Generate conditional branch selection

4 files changed, 253 insertions, 23 deletions

diff --git a/backend/lib/Target/RISCV/CMakeLists.txt b/backend/lib/Target/RISCV/CMakeLists.txt
index f9eb79f..48f3263 100644
--- a/backend/lib/Target/RISCV/CMakeLists.txt
+++ b/backend/lib/Target/RISCV/CMakeLists.txt
@@ -15,6 +15,7 @@ set(
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVInstrInfoZb.rccdesc"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVInstrInfoPseudo.rccdesc"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVGISelInteger.rccdesc"
+  "${CMAKE_CURRENT_SOURCE_DIR}/RISCVGISelControlFlow.rccdesc"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVGISelShift.rccdesc"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVGISelFloating.rccdesc"
 )
diff --git a/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/backend/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index 89b6ecd..1e2eb92 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_BRCOND:
       return {};
     case GenericOpcode::G_FCONSTANT: {
       const MachineOperand *Immediate = Instruction.operandAt(1);
@@ -440,8 +439,6 @@ public:
       return selectStore(Instruction, Function);
     case GenericOpcode::G_FPTRUNCSTORE:
       return selectFloatTruncStore(Instruction, Function, Target);
-    case GenericOpcode::G_BRCOND:
-      return selectConditionalBranch(Instruction);
     case GenericOpcode::G_CONSTANT:
       return selectIntegerConstant(Instruction, Function, Target, Type);
     case GenericOpcode::G_FCONSTANT:
@@ -1422,16 +1419,6 @@ private:
     return makeUnexpected(ErrorCode::Unsupported, "RISC-V cannot select this generic store type");
   }
 
-  [[nodiscard]] Expected<void> selectConditionalBranch(MachineInstr &Instruction) const {
-    auto Zero = physicalRegister(PhysicalRegisterID::X0);
-    if (!Zero)
-      return std::unexpected(Zero.error());
-    auto Inserted = insertPhysicalRegister(Instruction, 1, *Zero, RegisterOperandFlag::Use);
-    if (!Inserted)
-      return std::unexpected(Inserted.error());
-    return Instruction.setOpcode(instructionOpcode(InstructionOpcode::BNE));
-  }
-
   [[nodiscard]] Expected<void> selectIntegerConstant(MachineInstr &Instruction,
                                                      MachineFunction &Function,
                                                      const TargetDescription &Target,
diff --git a/backend/lib/Target/RISCV/RISCVGISelControlFlow.rccdesc b/backend/lib/Target/RISCV/RISCVGISelControlFlow.rccdesc
new file mode 100644
index 0000000..c58135f
--- /dev/null
+++ b/backend/lib/Target/RISCV/RISCVGISelControlFlow.rccdesc
@@ -0,0 +1,252 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+selection_rules:
+  -
+    id: select_g_br
+    priority: 100
+    match:
+      opcode: G_BR
+    apply:
+      instructions:
+        - opcode: PseudoBR
+          root: true
+          operands: [{ operand: 0 }]
+  -
+    id: select_g_brcond_sgt_minus_one
+    priority: 600
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: sgt }
+          captures:
+            - { id: lhs, operand: 2 }
+          operand_def_constants:
+            - index: 3
+              ranges: [{ min: -1, max: -1 }]
+    apply:
+      instructions:
+        - opcode: BGE
+          root: true
+          operands:
+            - { captured_operand: lhs }
+            - { physical_register: X0, flags: [use] }
+            - { operand: 1 }
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_slt_one
+    priority: 600
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: slt }
+          captures:
+            - { id: lhs, operand: 2 }
+          operand_def_constants:
+            - index: 3
+              ranges: [{ min: 1, max: 1 }]
+    apply:
+      instructions:
+        - opcode: BGE
+          root: true
+          operands:
+            - { physical_register: X0, flags: [use] }
+            - { captured_operand: lhs }
+            - { operand: 1 }
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_eq
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: eq }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BEQ
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_ne
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: ne }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BNE
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_slt
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: slt }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BLT
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_sge
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: sge }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BGE
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_ult
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: ult }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BLTU
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_uge
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: uge }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BGEU
+          root: true
+          operands: [{ captured_operand: lhs }, { captured_operand: rhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_sgt
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: sgt }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BLT
+          root: true
+          operands: [{ captured_operand: rhs }, { captured_operand: lhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_sle
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: sle }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BGE
+          root: true
+          operands: [{ captured_operand: rhs }, { captured_operand: lhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_ugt
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: ugt }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BLTU
+          root: true
+          operands: [{ captured_operand: rhs }, { captured_operand: lhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond_ule
+    priority: 400
+    match:
+      opcode: G_BRCOND
+      def_use:
+        - operand: 0
+          opcode: G_ICMP
+          integer_predicate: { index: 1, value: ule }
+          captures:
+            - { id: lhs, operand: 2 }
+            - { id: rhs, operand: 3 }
+    apply:
+      instructions:
+        - opcode: BGEU
+          root: true
+          operands: [{ captured_operand: rhs }, { captured_operand: lhs }, { operand: 1 }]
+      erase_operand_definitions: [0]
+  -
+    id: select_g_brcond
+    priority: 100
+    match:
+      opcode: G_BRCOND
+    apply:
+      instructions:
+        - opcode: BNE
+          root: true
+          operands:
+            - { operand: 0 }
+            - { physical_register: X0, flags: [use] }
+            - { operand: 1 }
diff --git a/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc b/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
index 6ba88ef..f40e5d4 100644
--- a/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
+++ b/backend/lib/Target/RISCV/RISCVGISelInteger.rccdesc
@@ -1,15 +1,5 @@
 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: