[flang] Add -f[no-]unroll-loops flag

clang/include/clang/Driver/Options.td

@@ -4157,9 +4157,9 @@ def ftrap_function_EQ : Joined<["-"], "ftrap-function=">, Group<f_Group>,
   HelpText<"Issue call to specified function rather than a trap instruction">,
   MarshallingInfoString<CodeGenOpts<"TrapFuncName">>;
 def funroll_loops : Flag<["-"], "funroll-loops">, Group<f_Group>,
-  HelpText<"Turn on loop unroller">, Visibility<[ClangOption, CC1Option]>;
+  HelpText<"Turn on loop unroller">, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>;
 def fno_unroll_loops : Flag<["-"], "fno-unroll-loops">, Group<f_Group>,
-  HelpText<"Turn off loop unroller">, Visibility<[ClangOption, CC1Option]>;
+  HelpText<"Turn off loop unroller">, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>;
 def ffinite_loops: Flag<["-"],  "ffinite-loops">, Group<f_Group>,
   HelpText<"Assume all non-trivial loops are finite.">, Visibility<[ClangOption, CC1Option]>;
 def fno_finite_loops: Flag<["-"], "fno-finite-loops">, Group<f_Group>,

clang/lib/Driver/ToolChains/Flang.cpp

@@ -155,7 +155,8 @@ void Flang::addCodegenOptions(const ArgList &Args,
                    options::OPT_flang_deprecated_no_hlfir,
                    options::OPT_fno_ppc_native_vec_elem_order,
                    options::OPT_fppc_native_vec_elem_order,
-                   options::OPT_ftime_report, options::OPT_ftime_report_EQ});
+                   options::OPT_ftime_report, options::OPT_ftime_report_EQ,
+                   options::OPT_funroll_loops, options::OPT_fno_unroll_loops});
 }
 
 void Flang::addPicOptions(const ArgList &Args, ArgStringList &CmdArgs) const {

flang/include/flang/Frontend/CodeGenOptions.def

@@ -32,6 +32,7 @@ CODEGENOPT(PrepareForThinLTO , 1, 0) ///< Set when -flto=thin is enabled on the
                                      ///< compile step.
 CODEGENOPT(StackArrays, 1, 0) ///< -fstack-arrays (enable the stack-arrays pass)
 CODEGENOPT(LoopVersioning, 1, 0) ///< Enable loop versioning.
+CODEGENOPT(UnrollLoops, 1, 0) ///< Enable loop unrolling
 CODEGENOPT(AliasAnalysis, 1, 0) ///< Enable alias analysis pass
 
 CODEGENOPT(Underscoring, 1, 1)

flang/lib/Frontend/CompilerInvocation.cpp

@@ -246,6 +246,10 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
                    clang::driver::options::OPT_fno_loop_versioning, false))
     opts.LoopVersioning = 1;
 
+  opts.UnrollLoops = args.hasFlag(clang::driver::options::OPT_funroll_loops,
+                                  clang::driver::options::OPT_fno_unroll_loops,
+                                  (opts.OptimizationLevel > 1));
+
   opts.AliasAnalysis = opts.OptimizationLevel > 0;
 
   // -mframe-pointer=none/non-leaf/all option.

flang/lib/Frontend/FrontendActions.cpp

@@ -1028,6 +1028,8 @@ void CodeGenAction::runOptimizationPipeline(llvm::raw_pwrite_stream &os) {
   si.registerCallbacks(pic, &mam);
   if (ci.isTimingEnabled())
     si.getTimePasses().setOutStream(ci.getTimingStreamLLVM());
+  pto.LoopUnrolling = opts.UnrollLoops;
+  pto.LoopInterleaving = opts.UnrollLoops;
   llvm::PassBuilder pb(targetMachine, pto, pgoOpt, &pic);
 
   // Attempt to load pass plugins and register their callbacks with PB.

flang/test/Driver/funroll-loops.f90

@@ -0,0 +1,5 @@
+! RUN: %flang -### -funroll-loops %s 2>&1 | FileCheck %s -check-prefix UNROLL
+! RUN: %flang -### -fno-unroll-loops %s 2>&1 | FileCheck %s -check-prefix NO-UNROLL
+
+! UNROLL: "-funroll-loops"
+! NO-UNROLL: "-fno-unroll-loops"

flang/test/HLFIR/unroll-loops.fir

@@ -0,0 +1,39 @@
+// RUN: %flang_fc1 -emit-llvm -O1 -funroll-loops -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,UNROLL
+// RUN: %flang_fc1 -emit-llvm -O2 -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,UNROLL
+// RUN: %flang_fc1 -emit-llvm -O1 -fno-unroll-loops -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,NO-UNROLL
+// RUN: %flang_fc1 -emit-llvm -O1 -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,NO-UNROLL
+
+// CHECK-LABEL: @unroll
+// CHECK-SAME: (ptr nocapture writeonly %[[ARG0:.*]])
+func.func @unroll(%arg0: !fir.ref<!fir.array<1000 x index>> {fir.bindc_name = "a"}) {
+  %scope = fir.dummy_scope : !fir.dscope
+  %c1000 = arith.constant 1000 : index
+  %shape = fir.shape %c1000 : (index) -> !fir.shape<1>
+  %a:2 = hlfir.declare %arg0(%shape) dummy_scope %scope {uniq_name = "unrollEa"} : (!fir.ref<!fir.array<1000xindex>>, !fir.shape<1>, !fir.dscope) -> (!fir.ref<!fir.array<1000 x index>>, !fir.ref<!fir.array<1000 x index>>)
+  %c1 = arith.constant 1 : index
+  fir.do_loop %arg1 = %c1 to %c1000 step %c1 {
+    // CHECK: br label %[[BLK:.*]]
+    // CHECK: [[BLK]]:
+    // CHECK-NEXT: %[[IND:.*]] = phi i64 [ 0, %{{.*}} ], [ %[[NIV:.*]], %[[BLK]] ]
+    // CHECK-NEXT: %[[VIND:.*]] = phi <2 x i64> [ <i64 1, i64 2>, %{{.*}} ], [ %[[NVIND:.*]], %[[BLK]] ]
+
+    // NO-UNROLL-NEXT: %[[GEP:.*]] = getelementptr i64, ptr %[[ARG0]], i64 %[[IND]]
+    // NO-UNROLL-NEXT: store <2 x i64> %[[VIND]], ptr %[[GEP]]
+    // NO-UNROLL-NEXT: %[[NIV:.*]] = add nuw i64 %{{.*}}, 2
+    // NO-UNROLL-NEXT: %[[NVIND]] = add <2 x i64> %[[VIND]], splat (i64 2)
+
+    // UNROLL-NEXT: %[[VIND1:.*]] = add <2 x i64> %[[VIND]], splat (i64 2)
+    // UNROLL-NEXT: %[[GEP0:.*]] = getelementptr i64, ptr %[[ARG0]], i64 %[[IND]]
+    // UNROLL-NEXT: %[[GEP1:.*]] = getelementptr i8, ptr %[[GEP0]], i64 16
+    // UNROLL-NEXT: store <2 x i64> %[[VIND]], ptr %[[GEP0]]
+    // UNROLL-NEXT: store <2 x i64> %[[VIND1]], ptr %[[GEP1]]
+    // UNROLL-NEXT: %[[NIV:.*]] = add nuw i64 %[[IND]], 4
+    // UNROLL-NEXT: %[[NVIND:.*]] = add <2 x i64> %[[VIND]], splat (i64 4)
+
+    // CHECK-NEXT: %[[EXIT:.*]] = icmp eq i64 %[[NIV]], 1000
+    // CHECK-NEXT: br i1 %[[EXIT]], label %{{.*}}, label %[[BLK]]
+    %ai = hlfir.designate %a#0 (%arg1)  : (!fir.ref<!fir.array<1000 x index>>, index) -> !fir.ref<index>
+    hlfir.assign %arg1 to %ai : index, !fir.ref<index>
+  }
+  return
+}

flang/test/Integration/unroll-loops.f90

@@ -0,0 +1,34 @@
+! RUN: %flang_fc1 -emit-llvm -O1 -funroll-loops -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,UNROLL
+! RUN: %flang_fc1 -emit-llvm -O2 -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,UNROLL
+! RUN: %flang_fc1 -emit-llvm -O1 -fno-unroll-loops -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,NO-UNROLL
+! RUN: %flang_fc1 -emit-llvm -O1 -mllvm -force-vector-width=2 -o- %s | FileCheck %s --check-prefixes=CHECK,NO-UNROLL
+
+! CHECK-LABEL: @unroll
+! CHECK-SAME: (ptr nocapture writeonly %[[ARG0:.*]])
+subroutine unroll(a)
+  integer(kind=8), intent(out) :: a(1000)
+  integer(kind=8) :: i
+    ! CHECK: br label %[[BLK:.*]]
+    ! CHECK: [[BLK]]:
+    ! CHECK-NEXT: %[[IND:.*]] = phi i64 [ 0, %{{.*}} ], [ %[[NIV:.*]], %[[BLK]] ]
+    ! CHECK-NEXT: %[[VIND:.*]] = phi <2 x i64> [ <i64 1, i64 2>, %{{.*}} ], [ %[[NVIND:.*]], %[[BLK]] ]
+    !
+    ! NO-UNROLL-NEXT: %[[GEP:.*]] = getelementptr i64, ptr %[[ARG0]], i64 %[[IND]]
+    ! NO-UNROLL-NEXT: store <2 x i64> %[[VIND]], ptr %[[GEP]]
+    ! NO-UNROLL-NEXT: %[[NIV:.*]] = add nuw i64 %{{.*}}, 2
+    ! NO-UNROLL-NEXT: %[[NVIND]] = add <2 x i64> %[[VIND]], splat (i64 2)
+    !
+    ! UNROLL-NEXT: %[[VIND1:.*]] = add <2 x i64> %[[VIND]], splat (i64 2)
+    ! UNROLL-NEXT: %[[GEP0:.*]] = getelementptr i64, ptr %[[ARG0]], i64 %[[IND]]
+    ! UNROLL-NEXT: %[[GEP1:.*]] = getelementptr i8, ptr %[[GEP0]], i64 16
+    ! UNROLL-NEXT: store <2 x i64> %[[VIND]], ptr %[[GEP0]]
+    ! UNROLL-NEXT: store <2 x i64> %[[VIND1]], ptr %[[GEP1]]
+    ! UNROLL-NEXT: %[[NIV:.*]] = add nuw i64 %[[IND]], 4
+    ! UNROLL-NEXT: %[[NVIND:.*]] = add <2 x i64> %[[VIND]], splat (i64 4)
+    !
+    ! CHECK-NEXT: %[[EXIT:.*]] = icmp eq i64 %[[NIV]], 1000
+    ! CHECK-NEXT: br i1 %[[EXIT]], label %{{.*}}, label %[[BLK]]
+  do i=1,1000
+    a(i) = i
+  end do
+end subroutine