[RISCV] Add basic support for inline asm constraints

llvm-svn: 322217

1 files changed, 55 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
index 4808e6c73c5..bbaa8ec454f 100644
--- a/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
+++ b/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
@@ -41,6 +41,13 @@ public:
 
   void EmitInstruction(const MachineInstr *MI) override;
 
+  bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
+                       unsigned AsmVariant, const char *ExtraCode,
+                       raw_ostream &OS) override;
+  bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
+                             unsigned AsmVariant, const char *ExtraCode,
+                             raw_ostream &OS) override;
+
   bool emitPseudoExpansionLowering(MCStreamer &OutStreamer,
                                    const MachineInstr *MI);
 
@@ -65,6 +72,54 @@ void RISCVAsmPrinter::EmitInstruction(const MachineInstr *MI) {
   EmitToStreamer(*OutStreamer, TmpInst);
 }
 
+bool RISCVAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
+                                      unsigned AsmVariant,
+                                      const char *ExtraCode, raw_ostream &OS) {
+  if (AsmVariant != 0)
+    report_fatal_error("There are no defined alternate asm variants");
+
+  // First try the generic code, which knows about modifiers like 'c' and 'n'.
+  if (!AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, OS))
+    return false;
+
+  if (!ExtraCode) {
+    const MachineOperand &MO = MI->getOperand(OpNo);
+    switch (MO.getType()) {
+    case MachineOperand::MO_Immediate:
+      OS << MO.getImm();
+      return false;
+    case MachineOperand::MO_Register:
+      OS << RISCVInstPrinter::getRegisterName(MO.getReg());
+      return false;
+    default:
+      break;
+    }
+  }
+
+  return true;
+}
+
+bool RISCVAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
+                                            unsigned OpNo, unsigned AsmVariant,
+                                            const char *ExtraCode,
+                                            raw_ostream &OS) {
+  if (AsmVariant != 0)
+    report_fatal_error("There are no defined alternate asm variants");
+
+  if (!ExtraCode) {
+    const MachineOperand &MO = MI->getOperand(OpNo);
+    // For now, we only support register memory operands in registers and
+    // assume there is no addend
+    if (!MO.isReg())
+      return true;
+
+    OS << "0(" << RISCVInstPrinter::getRegisterName(MO.getReg()) << ")";
+    return false;
+  }
+
+  return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, AsmVariant, ExtraCode, OS);
+}
+
 // Force static initialization.
 extern "C" void LLVMInitializeRISCVAsmPrinter() {
   RegisterAsmPrinter<RISCVAsmPrinter> X(getTheRISCV32Target());