[flang][NFC] Create required Source dir for flang-doc.

[vzakhari]

No description provided.

[DavidTruby]

LGTM

[tarunprabhu]

LGTM. Thanks Slava.

[llvm-ci]

LLVM Buildbot has detected a new failure on builder flang-aarch64-sharedlibs running on linaro-flang-aarch64-sharedlibs while building flang at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/80/builds/12171

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-flang) failure: test (failure)
******************** TEST 'Flang :: Transforms/DoConcurrent/loop_nest_test.f90' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4xi64>, i32 = dense<32> : vector<2xi64>, i1 = dense<8> : vector<2xi64>, i64 = dense<64> : vector<2xi64>, !llvm.ptr<270> = dense<32> : vector<4xi64>, i128 = dense<128> : vector<2xi64>, i8 = dense<[8, 32]> : vector<2xi64>, i16 = dense<[16, 32]> : vector<2xi64>, f16 = dense<16> : vector<2xi64>, f128 = dense<128> : vector<2xi64>, !llvm.ptr<272> = dense<64> : vector<4xi64>, !llvm.ptr<271> = dense<32> : vector<4xi64>, f64 = dense<64> : vector<2xi64>, "dlti.mangling_mode" = "e", "dlti.stack_alignment" = 128 : i64, "dlti.endianness" = "little">, fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32", llvm.ident = "flang version 21.0.0 (https://github.com/llvm/llvm-project.git b8b752db2b89a730aff250a83b64c7ed10d95ca0)", llvm.target_triple = "aarch64-unknown-linux-gnu", omp.is_gpu = false, omp.is_target_device = false, omp.target_triples = [], omp.version = #omp.version<version = 31>} {
  func.func @_QQmain() attributes {fir.bindc_name = "main"} {
    return
  }
  func.func private @_QFPfoo(%arg0: !fir.ref<i32> {fir.bindc_name = "n"}) attributes {fir.host_symbol = @_QQmain, llvm.linkage = #llvm.linkage<internal>} {
    %0 = fir.alloca i32 {bindc_name = "k"}
    %1:2 = hlfir.declare %0 {uniq_name = "_QFFfooEk"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %2 = fir.alloca i32 {bindc_name = "j"}
    %3:2 = hlfir.declare %2 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %4 = fir.alloca i32 {bindc_name = "i"}
    %5:2 = hlfir.declare %4 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %6 = fir.alloca i32 {bindc_name = "j"}
    %7:2 = hlfir.declare %6 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %8 = fir.alloca i32 {bindc_name = "i"}
    %9:2 = hlfir.declare %8 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %10 = fir.alloca i32 {bindc_name = "j"}
    %11:2 = hlfir.declare %10 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %12 = fir.alloca i32 {bindc_name = "i"}
    %13:2 = hlfir.declare %12 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %14 = fir.alloca i32 {bindc_name = "j"}
    %15:2 = hlfir.declare %14 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %16 = fir.alloca i32 {bindc_name = "i"}
    %17:2 = hlfir.declare %16 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %18 = fir.alloca i32 {bindc_name = "j"}
    %19:2 = hlfir.declare %18 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %20 = fir.alloca i32 {bindc_name = "i"}
    %21:2 = hlfir.declare %20 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %22 = fir.alloca i32 {bindc_name = "j"}
    %23:2 = hlfir.declare %22 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %24 = fir.alloca i32 {bindc_name = "i"}
    %25:2 = hlfir.declare %24 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %26 = fir.alloca i32 {bindc_name = "j"}
    %27:2 = hlfir.declare %26 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %28 = fir.alloca i32 {bindc_name = "i"}
    %29:2 = hlfir.declare %28 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %30 = fir.dummy_scope : !fir.dscope
    %31:2 = hlfir.declare %arg0 dummy_scope %30 {uniq_name = "_QFFfooEn"} : (!fir.ref<i32>, !fir.dscope) -> (!fir.ref<i32>, !fir.ref<i32>)
    %32 = fir.alloca i32 {bindc_name = "i", uniq_name = "_QFFfooEi"}
    %33:2 = hlfir.declare %32 {uniq_name = "_QFFfooEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %34 = fir.alloca i32 {bindc_name = "j", uniq_name = "_QFFfooEj"}
    %35:2 = hlfir.declare %34 {uniq_name = "_QFFfooEj"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %36 = fir.alloca i32 {bindc_name = "k", uniq_name = "_QFFfooEk"}
    %37:2 = hlfir.declare %36 {uniq_name = "_QFFfooEk"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
    %38 = fir.alloca i32 {bindc_name = "m", uniq_name = "_QFFfooEm"}
    %39:2 = hlfir.declare %38 {uniq_name = "_QFFfooEm"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
...