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[flang] AliasAnalysis: distinguish addr of arg vs. addr in arg #87723
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[flang] AliasAnalysis: distinguish addr of arg vs. addr in arg
jdenny-ornl b4124cf
Fix case of allocatable arg
jdenny-ornl fd358af
Apply clang-format
jdenny-ornl 75e2a26
Improve dummy argument identification
jdenny-ornl ca7a18b
Rename a symbol in a test for consistency
jdenny-ornl 0af947a
Merge branch 'main' into flang-aa-load-arg
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90 changes: 90 additions & 0 deletions
90
flang/test/Analysis/AliasAnalysis/alias-analysis-box-addr-load/arg.fir
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,90 @@ | ||
| // Check aliasing with the address passed via a pointer dummy argument. | ||
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| // Use --mlir-disable-threading so that the AA queries are serialized | ||
| // as well as its diagnostic output. | ||
| // RUN: fir-opt %s \ | ||
| // RUN: -pass-pipeline='builtin.module(func.func(test-fir-alias-analysis))' \ | ||
| // RUN: --mlir-disable-threading 2>&1 | FileCheck %s | ||
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| // subroutine test(p0, p1, arr, t_arr, alloc, t_alloc) | ||
| // real, pointer :: p0, p1 | ||
| // real :: arr(:) | ||
| // real, target :: t_arr(:) | ||
| // real, allocatable :: alloc | ||
| // real, allocatable, target :: t_alloc | ||
| // real, target :: t | ||
| // real :: v | ||
| // v = p0 | ||
| // v = p1 | ||
| // v = arr(1) | ||
| // v = t_arr(1) | ||
| // v = alloc | ||
| // v = t_alloc | ||
| // end subroutine test | ||
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| // CHECK-LABEL: Testing : "_QPtest" | ||
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| // The address in a pointer can alias the address in another pointer or the | ||
| // address of a target but not the address of other variables. | ||
| // CHECK-DAG: t.addr#0 <-> p0.tgt_addr#0: MayAlias | ||
| // CHECK-DAG: t.addr#0 <-> p1.tgt_addr#0: MayAlias | ||
| // CHECK-DAG: v.addr#0 <-> p0.tgt_addr#0: NoAlias | ||
| // CHECK-DAG: v.addr#0 <-> p1.tgt_addr#0: NoAlias | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> p1.tgt_addr#0: MayAlias | ||
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| // Determining whether the address *in* a pointer can alias the address *of* a | ||
| // pointer is not yet handled. In the past, when it was the same pointer, that | ||
| // relationship was mistakenly determined to be MustAlias. | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> func.region0#0: MayAlias | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> func.region0#1: MayAlias | ||
| // CHECK-DAG: p1.tgt_addr#0 <-> func.region0#0: MayAlias | ||
| // CHECK-DAG: p1.tgt_addr#0 <-> func.region0#1: MayAlias | ||
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| // For some cases, AliasAnalysis analyzes hlfir.designate like fir.box_addr, so | ||
| // make sure it doesn't mistakenly see arr(1).addr as an address that was loaded | ||
| // from a pointer and that could alias something. However, t_arr is a target. | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> arr(1).addr#0: NoAlias | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> t_arr(1).addr#0: MayAlias | ||
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| // Like a pointer, an allocatable contains an address, but an allocatable is not | ||
| // a pointer and so cannot alias pointers. However, t_alloc is a target. | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> alloc.tgt_addr#0: NoAlias | ||
| // CHECK-DAG: p0.tgt_addr#0 <-> t_alloc.tgt_addr#0: MayAlias | ||
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| func.func @_QPtest(%arg0: !fir.ref<!fir.box<!fir.ptr<f32>>> {fir.bindc_name = "p0"}, %arg1: !fir.ref<!fir.box<!fir.ptr<f32>>> {fir.bindc_name = "p1"}, %arg2: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "arr"}, %arg3: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "t_arr", fir.target}, %arg4: !fir.ref<!fir.box<!fir.heap<f32>>> {fir.bindc_name = "alloc"}, %arg5: !fir.ref<!fir.box<!fir.heap<f32>>> {fir.bindc_name = "t_alloc", fir.target}) attributes {test.ptr="func"} { | ||
| %0:2 = hlfir.declare %arg4 {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFtestEalloc"} : (!fir.ref<!fir.box<!fir.heap<f32>>>) -> (!fir.ref<!fir.box<!fir.heap<f32>>>, !fir.ref<!fir.box<!fir.heap<f32>>>) | ||
| %1:2 = hlfir.declare %arg2 {uniq_name = "_QFtestEarr"} : (!fir.box<!fir.array<?xf32>>) -> (!fir.box<!fir.array<?xf32>>, !fir.box<!fir.array<?xf32>>) | ||
| %2:2 = hlfir.declare %arg0 {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFtestEp0"} : (!fir.ref<!fir.box<!fir.ptr<f32>>>) -> (!fir.ref<!fir.box<!fir.ptr<f32>>>, !fir.ref<!fir.box<!fir.ptr<f32>>>) | ||
| %3:2 = hlfir.declare %arg1 {fortran_attrs = #fir.var_attrs<pointer>, uniq_name = "_QFtestEp1"} : (!fir.ref<!fir.box<!fir.ptr<f32>>>) -> (!fir.ref<!fir.box<!fir.ptr<f32>>>, !fir.ref<!fir.box<!fir.ptr<f32>>>) | ||
| %4 = fir.alloca f32 {bindc_name = "t", fir.target, uniq_name = "_QFtestEt"} | ||
| %5:2 = hlfir.declare %4 {fortran_attrs = #fir.var_attrs<target>, uniq_name = "_QFtestEt", test.ptr="t.addr"} : (!fir.ref<f32>) -> (!fir.ref<f32>, !fir.ref<f32>) | ||
| %6:2 = hlfir.declare %arg5 {fortran_attrs = #fir.var_attrs<allocatable, target>, uniq_name = "_QFtestEt_alloc"} : (!fir.ref<!fir.box<!fir.heap<f32>>>) -> (!fir.ref<!fir.box<!fir.heap<f32>>>, !fir.ref<!fir.box<!fir.heap<f32>>>) | ||
| %7:2 = hlfir.declare %arg3 {fortran_attrs = #fir.var_attrs<target>, uniq_name = "_QFtestEt_arr"} : (!fir.box<!fir.array<?xf32>>) -> (!fir.box<!fir.array<?xf32>>, !fir.box<!fir.array<?xf32>>) | ||
| %8 = fir.alloca f32 {bindc_name = "v", uniq_name = "_QFtestEv"} | ||
| %9:2 = hlfir.declare %8 {uniq_name = "_QFtestEv", test.ptr="v.addr"} : (!fir.ref<f32>) -> (!fir.ref<f32>, !fir.ref<f32>) | ||
| %10 = fir.load %2#0 : !fir.ref<!fir.box<!fir.ptr<f32>>> | ||
| %11 = fir.box_addr %10 {test.ptr="p0.tgt_addr"} : (!fir.box<!fir.ptr<f32>>) -> !fir.ptr<f32> | ||
| %12 = fir.load %11 : !fir.ptr<f32> | ||
| hlfir.assign %12 to %9#0 : f32, !fir.ref<f32> | ||
| %13 = fir.load %3#0 : !fir.ref<!fir.box<!fir.ptr<f32>>> | ||
| %14 = fir.box_addr %13 {test.ptr="p1.tgt_addr"} : (!fir.box<!fir.ptr<f32>>) -> !fir.ptr<f32> | ||
| %15 = fir.load %14 : !fir.ptr<f32> | ||
| hlfir.assign %15 to %9#0 : f32, !fir.ref<f32> | ||
| %c1 = arith.constant 1 : index | ||
| %16 = hlfir.designate %1#0 (%c1) {test.ptr="arr(1).addr"} : (!fir.box<!fir.array<?xf32>>, index) -> !fir.ref<f32> | ||
| %17 = fir.load %16 : !fir.ref<f32> | ||
| hlfir.assign %17 to %9#0 : f32, !fir.ref<f32> | ||
| %c1_0 = arith.constant 1 : index | ||
| %18 = hlfir.designate %7#0 (%c1_0) {test.ptr="t_arr(1).addr"} : (!fir.box<!fir.array<?xf32>>, index) -> !fir.ref<f32> | ||
| %19 = fir.load %18 : !fir.ref<f32> | ||
| hlfir.assign %19 to %9#0 : f32, !fir.ref<f32> | ||
| %20 = fir.load %0#0 : !fir.ref<!fir.box<!fir.heap<f32>>> | ||
| %21 = fir.box_addr %20 {test.ptr="alloc.tgt_addr"} : (!fir.box<!fir.heap<f32>>) -> !fir.heap<f32> | ||
| %22 = fir.load %21 : !fir.heap<f32> | ||
| hlfir.assign %22 to %9#0 : f32, !fir.ref<f32> | ||
| %23 = fir.load %6#0 : !fir.ref<!fir.box<!fir.heap<f32>>> | ||
| %24 = fir.box_addr %23 {test.ptr="t_alloc.tgt_addr"} : (!fir.box<!fir.heap<f32>>) -> !fir.heap<f32> | ||
| %25 = fir.load %24 : !fir.heap<f32> | ||
| hlfir.assign %25 to %9#0 : f32, !fir.ref<f32> | ||
| return | ||
| } |
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It looks good overall. The test change looks correct.
Why do we need this condition :
&& attributes.test(Attribute::Pointer)?It should be symmetric with the AddrOfOp.
Uh oh!
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For this
isDummyArg()case: The pointer check is needed to exclude dummy arguments of type!fir.box<!fir.array<...>>. This is in part because followBoxAddr is set when DesignateOp is applied to a!fir.box.For the AddrOfOp case: I didn't figure out how to get flang to generate a global with that type, even after asking in flang slack #general. I did find that flang/test/Fir/cg-ops.fir has such a global (again, I don't know the corresponding fortran). However, AddrOfOp turns even that into a
!fir.ref, so followBoxAddr isn't set at the DesignateOp, so I still don't know how to create the problem for AddrOfOp.Uh oh!
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For the AddrOfOp case: I noticed that flang/test/Analysis/AliasAnalysis/alias-analysis-8.fir expects the relationship between the address in an allocatable global and the address of that allocatable global to be NoAlias.
For the isDummyArg() case: I just checked the same relationship for allocatable arguments and discovered my patch wasn't handling it correctly: it has it as MustAlias. The pointer check we're discussing is too strict. I'll push a patch to this PR shortly that relaxes that to
fir::isa_ref_type(ty)to turn it into NoAlias. However, flang/test/Transforms/tbaa2.fir then fails because AddAliasTags cannot yet handle Direct for the allocatable arguments there. My new patch also attempts to extend AddAliasTags accordingly.I also tried adding
fir::isa_ref_type(ty)to the AddrOfOp case, and check-flang still behaved. So, it doesn't improve existing test cases, and I haven't found a!fir.box<!fir.array<...>>case for AddrOfOp (see previous comment), so for now I've abandoned that addition as apparently useless.