[RISCV] Handle "o" inline asm memory constraint

This is the same as D100412.

We just found the same crash when we tried to compile some packages
like mariadb, php, etc.

For constraint "o", it means "A memory operand is allowed, but
only if the address is offsettable". So I think it can be handled
just like constraint "m" for RISCV target.

And we print verbose information when unsupported constraints occur.

Reviewed By: asb

Differential Revision: https://reviews.llvm.org/D151979

llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp

@@ -2128,6 +2128,7 @@ bool RISCVDAGToDAGISel::SelectInlineAsmMemoryOperand(
   // Always produce a register and immediate operand, as expected by
   // RISCVAsmPrinter::PrintAsmMemoryOperand.
   switch (ConstraintID) {
+  case InlineAsm::Constraint_o:
   case InlineAsm::Constraint_m: {
     SDValue Op0, Op1;
     bool Found = SelectAddrRegImm(Op, Op0, Op1);
@@ -2143,7 +2144,8 @@ bool RISCVDAGToDAGISel::SelectInlineAsmMemoryOperand(
         CurDAG->getTargetConstant(0, SDLoc(Op), Subtarget->getXLenVT()));
     return false;
   default:
-    break;
+    report_fatal_error("Unexpected asm memory constraint " +
+                       InlineAsm::getMemConstraintName(ConstraintID));
   }
 
   return true;

llvm/test/CodeGen/RISCV/inline-asm.ll

@@ -101,6 +101,59 @@ define i32 @constraint_m_with_offset(ptr %a) nounwind {
   ret i32 %2
 }
 
+define void @constraint_o(ptr %a) nounwind {
+; RV32I-LABEL: constraint_o:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_o:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  call void asm sideeffect "", "=*o"(ptr elementtype(i32) %a)
+  ret void
+}
+
+define i32 @constraint_o2(ptr %a) nounwind {
+; RV32I-LABEL: constraint_o2:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    lw a0, 0(a0)
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_o2:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    lw a0, 0(a0)
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  %1 = tail call i32 asm "lw $0, $1", "=r,*o"(ptr elementtype(i32) %a)
+  ret i32 %1
+}
+
+define i32 @constraint_o_with_offset(ptr %a) nounwind {
+; RV32I-LABEL: constraint_o_with_offset:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    lw a0, 4(a0)
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_o_with_offset:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    lw a0, 4(a0)
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  %1 = getelementptr i32, ptr %a, i32 1
+  %2 = tail call i32 asm "lw $0, $1", "=r,*o"(ptr elementtype(i32) %1)
+  ret i32 %2
+}
+
 define void @constraint_I() nounwind {
 ; RV32I-LABEL: constraint_I:
 ; RV32I:       # %bb.0: