[flang] fixing alloca hoisting for blocks having single op. (#96009)

This change fixes the issue
https://github.com/llvm/llvm-project/issues/95977 due to commit
c0cba5198155dba246ddd5764f57595d9bbbddef inserting allocas after the
terminator op in the insertion block in the case where the block had
only a single operation, its terminator, in it. With this change, the
hoisted constant-sized allocas are placed at the front of the insertion
block, rather than right after the first operation in it.

3 files changed, 10 insertions, 7 deletions

diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index 803d9e6..5f35825 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -255,7 +255,7 @@ struct AllocaOpConversion : public fir::FIROpConversion<fir::AllocaOp> {
       mlir::Region *parentRegion = rewriter.getInsertionBlock()->getParent();
       mlir::Block *insertBlock =
           getBlockForAllocaInsert(parentOp, parentRegion);
-      size.getDefiningOp()->moveAfter(insertBlock, insertBlock->begin());
+      size.getDefiningOp()->moveBefore(&insertBlock->front());
       rewriter.setInsertionPointAfter(size.getDefiningOp());
     }
 
diff --git a/flang/test/Fir/convert-to-llvm-openmp-and-fir.fir b/flang/test/Fir/convert-to-llvm-openmp-and-fir.fir
index 45ff89b..396fbae 100644
--- a/flang/test/Fir/convert-to-llvm-openmp-and-fir.fir
+++ b/flang/test/Fir/convert-to-llvm-openmp-and-fir.fir
@@ -26,6 +26,7 @@ func.func @_QPsb1(%arg0: !fir.ref<i32> {fir.bindc_name = "n"}, %arg1: !fir.ref<!
 
 // CHECK-LABEL:  _QPsb1
 // CHECK-SAME: %[[N_REF:.*]]: !llvm.ptr {fir.bindc_name = "n"}, %[[ARR_REF:.*]]: !llvm.ptr {fir.bindc_name = "arr"}) {
+// CHECK:    %[[ONE_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:    %[[ONE_1:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:    %[[ONE_2:.*]] = llvm.mlir.constant(1 : i32) : i32
 // CHECK: omp.parallel   {
@@ -207,6 +208,7 @@ func.func @_QPsimd1(%arg0: !fir.ref<i32> {fir.bindc_name = "n"}, %arg1: !fir.ref
 
 // CHECK-LABEL:  _QPsimd1
 // CHECK-SAME: %[[N_REF:.*]]: !llvm.ptr {fir.bindc_name = "n"}, %[[ARR_REF:.*]]: !llvm.ptr {fir.bindc_name = "arr"}) {
+// CHECK:    %[[ONE_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:    %[[ONE_1:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:    %[[ONE_2:.*]] = llvm.mlir.constant(1 : i32) : i32
 // CHECK: omp.parallel   {
@@ -281,7 +283,6 @@ func.func @_QPomp_target_data() {
 }
 
 // CHECK-LABEL:   llvm.func @_QPomp_target_data() {
-// CHECK:           %[[VAL_0:.*]] = llvm.mlir.constant(1024 : index) : i64
 // CHECK:           %[[VAL_1:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_2:.*]] = llvm.alloca %[[VAL_1]] x !llvm.array<1024 x i32> {bindc_name = "d"} : (i64) -> !llvm.ptr
 // CHECK:           %[[VAL_3:.*]] = llvm.mlir.constant(1 : i64) : i64
@@ -290,6 +291,7 @@ func.func @_QPomp_target_data() {
 // CHECK:           %[[VAL_6:.*]] = llvm.alloca %[[VAL_5]] x !llvm.array<1024 x i32> {bindc_name = "b"} : (i64) -> !llvm.ptr
 // CHECK:           %[[VAL_7:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_8:.*]] = llvm.alloca %[[VAL_7]] x !llvm.array<1024 x i32> {bindc_name = "a"} : (i64) -> !llvm.ptr
+// CHECK:           %[[VAL_0:.*]] = llvm.mlir.constant(1024 : index) : i64
 // CHECK:           %[[VAL_9:.*]] = llvm.mlir.constant(1024 : index) : i64
 // CHECK:           %[[VAL_10:.*]] = llvm.mlir.constant(1024 : index) : i64
 // CHECK:           %[[VAL_11:.*]] = llvm.mlir.constant(1024 : index) : i64
@@ -373,9 +375,9 @@ func.func @_QPopenmp_target_data_region() {
 }
 
 // CHECK-LABEL:   llvm.func @_QPopenmp_target_data_region() {
-// CHECK:           %[[VAL_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_2:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_3:.*]] = llvm.alloca %[[VAL_2]] x i32 {bindc_name = "i"} : (i64) -> !llvm.ptr
+// CHECK:           %[[VAL_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_1:.*]] = llvm.alloca %[[VAL_0]] x !llvm.array<1024 x i32> {bindc_name = "a"} : (i64) -> !llvm.ptr
 // CHECK:           %[[VAL_MAX:.*]] = llvm.mlir.constant(1024 : index) : i64
 // CHECK:           %[[VAL_ONE:.*]] = llvm.mlir.constant(1 : index) : i64
@@ -459,15 +461,15 @@ func.func @_QPomp_target() {
 }
 
 // CHECK-LABEL:   llvm.func @_QPomp_target() {
-// CHECK:           %[[EXTENT:.*]] = llvm.mlir.constant(512 : index) : i64
 // CHECK:           %[[VAL_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:           %[[VAL_1:.*]] = llvm.alloca %[[VAL_0]] x !llvm.array<512 x i32> {bindc_name = "a"} : (i64) -> !llvm.ptr
+// CHECK:           %[[EXTENT:.*]] = llvm.mlir.constant(512 : index) : i64
 // CHECK:           %[[VAL_2:.*]] = llvm.mlir.constant(64 : i32) : i32
 // CHECK:           %[[STRIDE:.*]] = llvm.mlir.constant(1 : index) : i64
 // CHECK:           %[[LOWER:.*]] = llvm.mlir.constant(0 : index) : i64
 // CHECK:           %[[UPPER:.*]] = llvm.mlir.constant(511 : index) : i64
 // CHECK:           %[[BOUNDS:.*]] = omp.map.bounds   lower_bound(%[[LOWER]] : i64) upper_bound(%[[UPPER]] : i64) extent(%[[EXTENT]] : i64) stride(%[[STRIDE]] : i64) start_idx(%[[STRIDE]] : i64)
-// CHECK:           %[[MAP:.*]] = omp.map.info var_ptr(%2 : !llvm.ptr, !llvm.array<512 x i32>)   map_clauses(tofrom) capture(ByRef) bounds(%[[BOUNDS]]) -> !llvm.ptr {name = "a"}
+// CHECK:           %[[MAP:.*]] = omp.map.info var_ptr(%[[VAL_1]] : !llvm.ptr, !llvm.array<512 x i32>)   map_clauses(tofrom) capture(ByRef) bounds(%[[BOUNDS]]) -> !llvm.ptr {name = "a"}
 // CHECK:           omp.target   thread_limit(%[[VAL_2]] : i32) map_entries(%[[MAP]] -> %[[ARG_0:.*]] : !llvm.ptr) {
 // CHECK:           ^bb0(%[[ARG_0]]: !llvm.ptr):
 // CHECK:             %[[VAL_3:.*]] = llvm.mlir.constant(10 : i32) : i32
@@ -715,7 +717,8 @@ func.func @_QPsb() {
 // CHECK:  }
 // CHECK-LABEL:  @_QPsimple_reduction
 // CHECK-SAME: %[[ARRAY_REF:.*]]: !llvm.ptr
-// CHECK:    %[[RED_ACCUMULATOR:.*]] = llvm.alloca %1 x i32 {bindc_name = "x"} : (i64) -> !llvm.ptr
+// CHECK:    %[[VAL_1:.*]] = llvm.mlir.constant(1 : i64) : i64
+// CHECK:    %[[RED_ACCUMULATOR:.*]] = llvm.alloca %[[VAL_1]] x i32 {bindc_name = "x"} : (i64) -> !llvm.ptr
 // CHECK:    omp.parallel   {
 // CHECK:      omp.wsloop reduction(@[[EQV_REDUCTION]] %[[RED_ACCUMULATOR]] -> %[[PRV:.+]] : !llvm.ptr) {
 // CHECK-NEXT:   omp.loop_nest
diff --git a/flang/test/Fir/convert-to-llvm.fir b/flang/test/Fir/convert-to-llvm.fir
index c951445..c7f3160 100644
--- a/flang/test/Fir/convert-to-llvm.fir
+++ b/flang/test/Fir/convert-to-llvm.fir
@@ -2047,7 +2047,6 @@ func.func private @_QPtest_dt_callee(%arg0: !fir.box<!fir.array<?xi32>>)
 // GENERIC:       %[[ALLOCA:.*]] = llvm.alloca %[[ALLOCA_SIZE]] x !llvm.struct<(ptr, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, array<1 x array<3 x i64>>)> {alignment = 8 : i64} : (i32) -> !llvm.ptr
 // AMDGPU:        %[[AA:.*]] = llvm.alloca %[[ALLOCA_SIZE]] x !llvm.struct<(ptr, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, i{{.*}}, array<1 x array<3 x i64>>)> {alignment = 8 : i64} : (i32) -> !llvm.ptr<5>
 // AMDGPU:        %[[ALLOCA:.*]] = llvm.addrspacecast %[[AA]] : !llvm.ptr<5> to !llvm.ptr
-// CHECK:         %[[C20:.*]] = llvm.mlir.constant(20 : index) : i64
 // CHECK:         %[[ALLOCA_SIZE_X:.*]] = llvm.mlir.constant(1 : i64) : i64
 // GENERIC:       %[[X:.*]] = llvm.alloca %[[ALLOCA_SIZE_X]] x !llvm.array<20 x struct<"_QFtest_dt_sliceTt", (i32, i32)>> {bindc_name = "x"} : (i64) -> !llvm.ptr
 // AMDGPU:        %[[AC:.*]] = llvm.alloca %[[ALLOCA_SIZE_X]] x !llvm.array<20 x struct<"_QFtest_dt_sliceTt", (i32, i32)>> {bindc_name = "x"} : (i64) -> !llvm.ptr<5>
@@ -2056,6 +2055,7 @@ func.func private @_QPtest_dt_callee(%arg0: !fir.box<!fir.array<?xi32>>)
 // GENERIC:       %[[V:.*]] = llvm.alloca %[[ALLOCA_SIZE_V]] x i32 {bindc_name = "v"} : (i64) -> !llvm.ptr
 // AMDGPU:        %[[AB:.*]] = llvm.alloca %[[ALLOCA_SIZE_V]] x i32 {bindc_name = "v"} : (i64) -> !llvm.ptr<5>
 // AMDGPU:        %[[V:.*]] = llvm.addrspacecast %[[AB]] : !llvm.ptr<5> to !llvm.ptr
+// CHECK:         %[[C20:.*]] = llvm.mlir.constant(20 : index) : i64
 // CHECK:         %[[C1:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CHECK:         %[[C10:.*]] = llvm.mlir.constant(10 : i64) : i64
 // CHECK:         %[[C2:.*]] = llvm.mlir.constant(2 : i64) : i64