llvm · jeanPerier · Oct 2, 2023 · Sep 29, 2023
diff --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
@@ -101,6 +101,8 @@ end
 * `$` and `@` as legal characters in names
 * Initialization in type declaration statements using `/values/`
 * Saved variables without explicit or default initializers are zero initialized.
+* In a saved entity of a type with a default initializer, components without default
+  values are zero initialized.
 * Kind specification with `*`, e.g. `REAL*4`
 * `DOUBLE COMPLEX` as a synonym for `COMPLEX(KIND(0.D0))` --
   but not when spelled `TYPE(DOUBLECOMPLEX)`.

diff --git a/flang/lib/Lower/ConvertVariable.cpp b/flang/lib/Lower/ConvertVariable.cpp
@@ -352,16 +352,17 @@ static mlir::Value genDefaultInitializerValue(
         componentValue = genDefaultInitializerValue(converter, loc, component,
                                                     componentTy, stmtCtx);
       } else {
-        // Component has no initial value.
-        componentValue = builder.create<fir::UndefOp>(loc, componentTy);
+        // Component has no initial value. Set its bits to zero by extension
+        // to match what is expected because other compilers are doing it.
+        componentValue = builder.create<fir::ZeroOp>(loc, componentTy);
       }
     } else if (const auto *proc{
                    component
                        .detailsIf<Fortran::semantics::ProcEntityDetails>()}) {
       if (proc->init().has_value())
         TODO(loc, "procedure pointer component default initialization");
       else
-        componentValue = builder.create<fir::UndefOp>(loc, componentTy);
+        componentValue = builder.create<fir::ZeroOp>(loc, componentTy);
     }
     assert(componentValue && "must have been computed");
     componentValue = builder.createConvert(loc, componentTy, componentValue);
@@ -890,7 +891,7 @@ static fir::GlobalOp defineGlobalAggregateStore(
   Fortran::lower::createGlobalInitialization(
       builder, global, [&](fir::FirOpBuilder &builder) {
         Fortran::lower::StatementContext stmtCtx;
-        mlir::Value initVal = builder.create<fir::UndefOp>(loc, aggTy);
+        mlir::Value initVal = builder.create<fir::ZeroOp>(loc, aggTy);
         builder.create<fir::HasValueOp>(loc, initVal);
       });
   return global;
@@ -1171,7 +1172,7 @@ static void finalizeCommonBlockDefinition(
   mlir::TupleType commonTy = global.getType().cast<mlir::TupleType>();
   auto initFunc = [&](fir::FirOpBuilder &builder) {
     mlir::IndexType idxTy = builder.getIndexType();
-    mlir::Value cb = builder.create<fir::UndefOp>(loc, commonTy);
+    mlir::Value cb = builder.create<fir::ZeroOp>(loc, commonTy);
     unsigned tupIdx = 0;
     std::size_t offset = 0;
     LLVM_DEBUG(llvm::dbgs() << "block {\n");

diff --git a/flang/test/Lower/array.f90 b/flang/test/Lower/array.f90
@@ -4,7 +4,7 @@
 ! CHECK-DAG: %[[VAL_1:.*]] = arith.constant 1.000000e+00 : f32
 ! CHECK-DAG: %[[VAL_2:.*]] = arith.constant 2.400000e+00 : f32
 ! CHECK-DAG: %[[VAL_3:.*]] = arith.constant 0.000000e+00 : f32
-! CHECK: %[[VAL_4:.*]] = fir.undefined tuple<!fir.array<5x5xf32>>
+! CHECK: %[[VAL_4:.*]] = fir.zero_bits tuple<!fir.array<5x5xf32>>
 ! CHECK: %[[VAL_5:.*]] = fir.undefined !fir.array<5x5xf32>
 ! CHECK: %[[VAL_6:.*]] = fir.insert_on_range %[[VAL_5]], %[[VAL_1]] from (0, 0) to (1, 0) : (!fir.array<5x5xf32>, f32) -> !fir.array<5x5xf32>
 ! CHECK: %[[VAL_7:.*]] = fir.insert_on_range %[[VAL_6]], %[[VAL_3]] from (2, 0) to (4, 0) : (!fir.array<5x5xf32>, f32) -> !fir.array<5x5xf32>

diff --git a/flang/test/Lower/common-block-2.f90 b/flang/test/Lower/common-block-2.f90
@@ -6,12 +6,12 @@
 ! - A common block that is initialized outside of a BLOCK DATA.
 
 ! CHECK-LABEL: fir.global @__BLNK__ : tuple<i32, !fir.array<8xi8>> {
-! CHECK:  %[[undef:.*]] = fir.undefined tuple<i32, !fir.array<8xi8>>
+! CHECK:  %[[undef:.*]] = fir.zero_bits tuple<i32, !fir.array<8xi8>>
 ! CHECK:  %[[init:.*]] = fir.insert_value %[[undef]], %c42{{.*}}, [0 : index] : (tuple<i32, !fir.array<8xi8>>, i32) -> tuple<i32, !fir.array<8xi8>>
 ! CHECK:  fir.has_value %[[init]] : tuple<i32, !fir.array<8xi8>>
 
 ! CHECK-LABEL: fir.global @a_ : tuple<i32, !fir.array<8xi8>> {
-! CHECK:  %[[undef:.*]] = fir.undefined tuple<i32, !fir.array<8xi8>>
+! CHECK:  %[[undef:.*]] = fir.zero_bits tuple<i32, !fir.array<8xi8>>
 ! CHECK:  %[[init:.*]] = fir.insert_value %[[undef]], %c42{{.*}}, [0 : index] : (tuple<i32, !fir.array<8xi8>>, i32) -> tuple<i32, !fir.array<8xi8>>
 ! CHECK:  fir.has_value %[[init]] : tuple<i32, !fir.array<8xi8>>
 

diff --git a/flang/test/Lower/common-block.f90 b/flang/test/Lower/common-block.f90
@@ -6,7 +6,7 @@
 ! CHECK: @with_empty_equiv_ = common global [8 x i8] zeroinitializer
 ! CHECK: @x_ = global { float, float } { float 1.0{{.*}}, float 2.0{{.*}} }
 ! CHECK: @y_ = common global [12 x i8] zeroinitializer
-! CHECK: @z_ = global { i32, [4 x i8], float } { i32 42, [4 x i8] undef, float 3.000000e+00 }
+! CHECK: @z_ = global { i32, [4 x i8], float } { i32 42, [4 x i8] zeroinitializer, float 3.000000e+00 }
 
 ! CHECK-LABEL: _QPs0
 subroutine s0

diff --git a/flang/test/Lower/default-initialization-globals.f90 b/flang/test/Lower/default-initialization-globals.f90
@@ -97,7 +97,7 @@ module tinit
   ! CHECK-DAG: %[[VAL_15:.*]] = arith.constant 66 : i32
   ! CHECK: %[[VAL_16:.*]] = fir.undefined !fir.type<_QMtinitTt1{{.*}}>
   ! CHECK: %[[VAL_17:.*]] = fir.insert_value %[[VAL_16]], %[[VAL_11]], ["i", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, i32) -> !fir.type<_QMtinitTt1{{.*}}>
-  ! CHECK: %[[VAL_18:.*]] = fir.undefined i32
+  ! CHECK: %[[VAL_18:.*]] = fir.zero_bits i32
   ! CHECK: %[[VAL_19:.*]] = fir.insert_value %[[VAL_17]], %[[VAL_18]], ["j", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, i32) -> !fir.type<_QMtinitTt1{{.*}}>
   ! CHECK: %[[VAL_20:.*]] = fir.address_of(@_QMtinitEziel) : !fir.ref<!fir.array<100xf32>>
   ! CHECK: %[[VAL_21:.*]] = fir.shape %[[VAL_12]] : (index) -> !fir.shape<1>
@@ -111,12 +111,12 @@ module tinit
   ! CHECK: %[[VAL_28:.*]] = fir.insert_value %[[VAL_27]], %[[VAL_26]], ["z", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.box<!fir.ptr<!fir.array<?xf32>>>) -> !fir.type<_QMtinitTt1{{.*}}>
   ! CHECK: %[[VAL_29:.*]] = fir.string_lit "hello     "(10) : !fir.char<1,10>
   ! CHECK: %[[VAL_30:.*]] = fir.insert_value %[[VAL_28]], %[[VAL_29]], ["c1", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.char<1,10>) -> !fir.type<_QMtinitTt1{{.*}}>
-  ! CHECK: %[[VAL_31:.*]] = fir.undefined !fir.char<1,10>
+  ! CHECK: %[[VAL_31:.*]] = fir.zero_bits !fir.char<1,10>
   ! CHECK: %[[VAL_32:.*]] = fir.insert_value %[[VAL_30]], %[[VAL_31]], ["c2", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.char<1,10>) -> !fir.type<_QMtinitTt1{{.*}}>
   ! CHECK: %[[VAL_33:.*]] = fir.undefined !fir.type<_QMtinitTt0{k:i32}>
   ! CHECK: %[[VAL_34:.*]] = fir.insert_value %[[VAL_33]], %[[VAL_15]], ["k", !fir.type<_QMtinitTt0{k:i32}>] : (!fir.type<_QMtinitTt0{k:i32}>, i32) -> !fir.type<_QMtinitTt0{k:i32}>
   ! CHECK: %[[VAL_35:.*]] = fir.insert_value %[[VAL_32]], %[[VAL_34]], ["somet0", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.type<_QMtinitTt0{k:i32}>) -> !fir.type<_QMtinitTt1{{.*}}>
-  ! CHECK: %[[VAL_36:.*]] = fir.undefined !fir.type<_QMtinitTtno_init{k:i32}>
+  ! CHECK: %[[VAL_36:.*]] = fir.zero_bits !fir.type<_QMtinitTtno_init{k:i32}>
   ! CHECK: %[[VAL_37:.*]] = fir.insert_value %[[VAL_35]], %[[VAL_36]], ["sometno_init", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.type<_QMtinitTtno_init{k:i32}>) -> !fir.type<_QMtinitTt1{{.*}}>
   ! CHECK: %[[VAL_38:.*]] = fir.insert_value %[[VAL_33]], %[[VAL_14]], ["k", !fir.type<_QMtinitTt0{k:i32}>] : (!fir.type<_QMtinitTt0{k:i32}>, i32) -> !fir.type<_QMtinitTt0{k:i32}>
   ! CHECK: %[[VAL_39:.*]] = fir.insert_value %[[VAL_37]], %[[VAL_38]], ["somet0_2", !fir.type<_QMtinitTt1{{.*}}>] : (!fir.type<_QMtinitTt1{{.*}}>, !fir.type<_QMtinitTt0{k:i32}>) -> !fir.type<_QMtinitTt1{{.*}}>
@@ -129,7 +129,7 @@ module tinit
   ! CHECK: %[[VAL_42:.*]] = arith.constant 66 : i32
   ! CHECK: %[[VAL_43:.*]] = fir.undefined !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>
   ! CHECK: %[[VAL_44:.*]] = fir.insert_value %[[VAL_43]], %[[VAL_42]], ["k", !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>] : (!fir.type<_QMtinitTtextendst0{k:i32,l:i32}>, i32) -> !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>
-  ! CHECK: %[[VAL_45:.*]] = fir.undefined i32
+  ! CHECK: %[[VAL_45:.*]] = fir.zero_bits i32
   ! CHECK: %[[VAL_46:.*]] = fir.insert_value %[[VAL_44]], %[[VAL_45]], ["l", !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>] : (!fir.type<_QMtinitTtextendst0{k:i32,l:i32}>, i32) -> !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>
   ! CHECK: fir.has_value %[[VAL_46]] : !fir.type<_QMtinitTtextendst0{k:i32,l:i32}>
 

diff --git a/flang/test/Lower/equivalence-static-init.f90 b/flang/test/Lower/equivalence-static-init.f90
@@ -8,7 +8,7 @@ module module_without_init
   equivalence(i(1), x)
 end module
 ! CHECK-LABEL: fir.global @_QMmodule_without_initEi : !fir.array<8xi8> {
-  ! CHECK: %0 = fir.undefined !fir.array<8xi8>
+  ! CHECK: %0 = fir.zero_bits !fir.array<8xi8>
   ! CHECK: fir.has_value %0 : !fir.array<8xi8>
 ! CHECK}
 

diff --git a/flang/test/Lower/pointer-default-init.f90 b/flang/test/Lower/pointer-default-init.f90
@@ -21,7 +21,7 @@ module test
   type(t) :: test_module_var
 ! CHECK-LABEL:   fir.global @_QMtestEtest_module_var : !fir.type<_QMtestTt{i:i32,x:!fir.box<!fir.ptr<!fir.array<?xf32>>>}> {
 ! CHECK:  %[[VAL_0:.*]] = fir.undefined !fir.type<_QMtestTt{i:i32,x:!fir.box<!fir.ptr<!fir.array<?xf32>>>}>
-! CHECK:  %[[VAL_1:.*]] = fir.undefined i32
+! CHECK:  %[[VAL_1:.*]] = fir.zero_bits i32
 ! CHECK:  %[[VAL_2:.*]] = fir.field_index i
 ! CHECK:  %[[VAL_3:.*]] = fir.insert_value %[[VAL_0]], %[[VAL_1]]
 ! CHECK:  %[[VAL_4:.*]] = fir.zero_bits !fir.ptr<!fir.array<?xf32>>
@@ -97,7 +97,7 @@ subroutine test_saved_pointer()
 
 ! CHECK-LABEL:   fir.global internal @_QFtest_savedEx : !fir.type<_QMtestTt{i:i32,x:!fir.box<!fir.ptr<!fir.array<?xf32>>>}> {
 ! CHECK:  %[[VAL_0:.*]] = fir.undefined !fir.type<_QMtestTt{i:i32,x:!fir.box<!fir.ptr<!fir.array<?xf32>>>}>
-! CHECK:  %[[VAL_1:.*]] = fir.undefined i32
+! CHECK:  %[[VAL_1:.*]] = fir.zero_bits i32
 ! CHECK:  %[[VAL_2:.*]] = fir.field_index i
 ! CHECK:  %[[VAL_3:.*]] = fir.insert_value %[[VAL_0]], %[[VAL_1]]
 ! CHECK:  %[[VAL_4:.*]] = fir.zero_bits !fir.ptr<!fir.array<?xf32>>

diff --git a/flang/test/Lower/pointer-initial-target-2.f90 b/flang/test/Lower/pointer-initial-target-2.f90
@@ -12,7 +12,7 @@
   common /a/ p
   data p /b/
 ! CHECK-LABEL: fir.global @a_ : tuple<!fir.box<!fir.ptr<f32>>>
-  ! CHECK: %[[undef:.*]] = fir.undefined tuple<!fir.box<!fir.ptr<f32>>>
+  ! CHECK: %[[undef:.*]] = fir.zero_bits tuple<!fir.box<!fir.ptr<f32>>>
   ! CHECK: %[[b:.*]] = fir.address_of(@_QEb) : !fir.ref<f32>
   ! CHECK: %[[box:.*]] = fir.embox %[[b]] : (!fir.ref<f32>) -> !fir.box<f32>
   ! CHECK: %[[rebox:.*]] = fir.rebox %[[box]] : (!fir.box<f32>) -> !fir.box<!fir.ptr<f32>>
@@ -41,7 +41,7 @@ block data bdsnake
   integer, pointer :: p => b
   common /snake/ p, b
 ! CHECK-LABEL: fir.global @snake_ : tuple<!fir.box<!fir.ptr<i32>>, i32>
-  ! CHECK: %[[tuple0:.*]] = fir.undefined tuple<!fir.box<!fir.ptr<i32>>, i32>
+  ! CHECK: %[[tuple0:.*]] = fir.zero_bits tuple<!fir.box<!fir.ptr<i32>>, i32>
   ! CHECK: %[[snakeAddr:.*]] = fir.address_of(@snake_) : !fir.ref<tuple<!fir.box<!fir.ptr<i32>>, i32>>
   ! CHECK: %[[byteView:.*]] = fir.convert %[[snakeAddr:.*]] : (!fir.ref<tuple<!fir.box<!fir.ptr<i32>>, i32>>) -> !fir.ref<!fir.array<?xi8>>
   ! CHECK: %[[coor:.*]] = fir.coordinate_of %[[byteView]], %c24{{.*}} : (!fir.ref<!fir.array<?xi8>>, index) -> !fir.ref<i8>