[Clang][RISCV] Fix upper bound of RISC-V V type in debug info

The UpperBound of RVV type in debug info should be elements count minus one,
as the LowerBound start from zero.

Reviewed By: HsiangKai

Differential Revision: https://reviews.llvm.org/D115430

Author: jacquesguan

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -768,7 +768,7 @@ llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
       }
 
       // Element count = (VLENB / SEW) x LMUL
-      SmallVector<int64_t, 9> Expr(
+      SmallVector<int64_t, 12> Expr(
           // The DW_OP_bregx operation has two operands: a register which is
           // specified by an unsigned LEB128 number, followed by a signed LEB128
           // offset.
@@ -782,6 +782,8 @@ llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
         Expr.push_back(llvm::dwarf::DW_OP_div);
       else
         Expr.push_back(llvm::dwarf::DW_OP_mul);
+      // Element max index = count - 1
+      Expr.append({llvm::dwarf::DW_OP_constu, 1, llvm::dwarf::DW_OP_minus});
 
       auto *LowerBound =
           llvm::ConstantAsMetadata::get(llvm::ConstantInt::getSigned(

clang/test/CodeGen/RISCV/riscv-v-debuginfo.c

@@ -9,20 +9,20 @@ __rvv_int16m2_t f1(__rvv_int16m2_t arg_0, __rvv_int16m2_t arg_1, int64_t arg_2)
 }
 
 // !DISubrange(lowerBound: 0, upperBound: !DIExpression(DW_OP_bregx, 7202, 0, DW_OP_con
-// DEBUGINFO: stu, 2, DW_OP_div, DW_OP_constu, 2, DW_OP_mul))
+// DEBUGINFO: stu, 2, DW_OP_div, DW_OP_constu, 2, DW_OP_mul, DW_OP_constu, 1, DW_OP_minus))
 
 __rvv_int16mf2_t f2(__rvv_int16mf2_t arg_0, __rvv_int16mf2_t arg_1, int64_t arg_2) {
   __rvv_int16mf2_t ret;
   return ret;
 }
 
 // !DISubrange(lowerBound: 0, upperBound: !DIExpression(DW_OP_bregx, 7202, 0, DW_OP_con
-// DEBUGINFO: stu, 2, DW_OP_div, DW_OP_constu, 2, DW_OP_div))
+// DEBUGINFO: stu, 2, DW_OP_div, DW_OP_constu, 2, DW_OP_div, DW_OP_constu, 1, DW_OP_minus))
 
 __rvv_int32mf2_t f3(__rvv_int32mf2_t arg_0, __rvv_int32mf2_t arg_1, int64_t arg_2) {
   __rvv_int32mf2_t ret;
   return ret;
 }
 
 // !DISubrange(lowerBound: 0, upperBound: !DIExpression(DW_OP_bregx, 7202, 0, DW_OP_con
-// DEBUGINFO: stu, 4, DW_OP_div, DW_OP_constu, 2, DW_OP_div))
+// DEBUGINFO: stu, 4, DW_OP_div, DW_OP_constu, 2, DW_OP_div, DW_OP_constu, 1, DW_OP_minus))