[flang2] Generate loads of complex variables with correct alignment

flang2 calls the function make_load() to create various types of load
instructions in the LLVM IR output. The function accepts a "flags" argument
of type LL_InstrListFlags which should encode the alignment of the load,
among other things. Apparently, for the IL_LDSCMPLX, IL_LDDCMPLX, and
IL_LDQCMPLX opcodes, the flags had never been computed correctly. This
patch makes such loads consistent with loads of other types, and also adds
a test case.

Author: bryanpkc

test/llvm_ir_correct/load-alignment.f90

@@ -0,0 +1,50 @@
+! Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+! See https://llvm.org/LICENSE.txt for license information.
+! SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+! Check that load instructions are emitted with correct alignment.
+
+! RUN: %flang -S -emit-flang-llvm %s -o %t.ll
+! RUN: FileCheck %s < %t.ll
+
+! CHECK: load i8, ptr %in1, align 1
+function bpass(in1)
+  logical(kind=1) :: in1, bpass
+  bpass = in1
+end function bpass
+
+! CHECK: load i32, ptr %in1, align 4
+function ipass(in1)
+  integer(kind=4) :: in1, ipass
+  ipass = in1
+end function ipass
+
+! CHECK: load i64, ptr %in1, align 8
+function lpass(in1)
+  integer(kind=8) :: in1, lpass
+  lpass = in1
+end function lpass
+
+! CHECK: load float, ptr %in1, align 4
+function fpass(in1)
+  real(kind=4) :: in1, fpass
+  fpass = in1
+end function fpass
+
+! CHECK: load double, ptr %in1, align 8
+function dpass(in1)
+  real(kind=8) :: in1, dpass
+  dpass = in1
+end function dpass
+
+! CHECK: load <{float, float}>, ptr %in1, align 8
+function cfpass(in1)
+  complex(kind=4) :: in1, cfpass
+  cfpass = in1
+end function cfpass
+
+! CHECK: load <{double, double}>, ptr %in1, align 16
+function cdpass(in1)
+  complex(kind=8) :: in1, cdpass
+  cdpass = in1
+end function cdpass

tools/flang2/flang2exe/cgmain.cpp

@@ -8572,15 +8572,12 @@ gen_llvm_expr(int ilix, LL_Type *expected_type)
     ld_ili = ILI_OPND(ilix, 1);
     nme_ili = ILI_OPND(ilix, 2);
     msz = (MSZ)ILI_OPND(ilix, 3);
-    flags = opc == IL_LDSCMPLX ? DT_CMPLX
-#ifdef TARGET_SUPPORTS_QUADFP
-          : opc == IL_LDQCMPLX ? DT_QCMPLX
-#endif
-                               : DT_DCMPLX;
     operand = gen_address_operand(ld_ili, nme_ili, false,
                                   make_ptr_lltype(expected_type), (MSZ)-1);
     assert(operand->ll_type->data_type == LL_PTR,
            "Invalid operand for cmplx load", ilix, ERR_Fatal);
+    flags =
+        ldst_instr_flags_from_dtype_nme(msz_dtype(msz), nme_ili);
     operand =
         make_load(ilix, operand, operand->ll_type->sub_types[0], msz, flags);
   } break;