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[flang][TBAA] refine TARGET/POINTER encoding (llvm#169544)
Previously we were less specific for POINTER/TARGET: encoding that they could alias with (almost) anything. In the new system, the "target data" tree is now a sibling of the other trees (e.g. "global data"). POITNTER variables go at the root of the "target data" tree, whereas TARGET variables get their own nodes under that tree. For example, ``` integer, pointer :: ip real, pointer :: rp integer, target :: it integer, target :: it2(:) real, target :: rt integer :: i real :: r ``` - `ip` and `rp` may alias with any variable except `i` and `r`. - `it`, `it2`, and `rt` may alias only with `ip` or `rp`. - `i` and `r` cannot alias with any other variable. Fortran 2023 15.5.2.14 gives restrictions on entities associated with dummy arguments. These do not allow non-target globals to be modified through dummy arguments and therefore I don't think we need to make all globals alias with dummy arguments. I haven't implemented it in this patch, but I wonder whether it is ever possible for `ip` to alias with `rt` or even `it2`. While I was updating the tests I fixed up some tests that still assumed that local alloc tbaa wasn't the default. I found no functional regressions in the gfortran test suite, fujitsu test suite, spec2017, or a selection of HPC apps we test internally.
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‎flang/include/flang/Optimizer/Analysis/TBAAForest.h‎

Lines changed: 19 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -99,11 +99,25 @@ struct TBAATree {
9999
// |- "any data access"
100100
// |
101101
// |- "dummy arg data"
102-
// |- "target data"
103-
// |
104-
// |- "allocated data"
105-
// |- "direct data"
106-
// |- "global data"
102+
// |
103+
// |- <dummy arg name 1>
104+
// |- <dummy arg name 2>
105+
// |- "target data" <-- Any POINTER variable or TARGET dummy arg
106+
// |
107+
// |- <target name 1> <--- any TARGET variable which isn't a dummy arg
108+
// |- <target name 2>
109+
// |- "allocated data"
110+
// |
111+
// |- <allocated name 1>
112+
// |- <allocated name 2>
113+
// |- "direct data"
114+
// |
115+
// |- <direct name 1>
116+
// |- <direct name 2>
117+
// |- "global data"
118+
// |
119+
// |- <global name 1>
120+
// |- <global name 2>
107121
static TBAATree buildTree(mlir::StringAttr functionName);
108122

109123
private:

‎flang/lib/Optimizer/Analysis/TBAAForest.cpp‎

Lines changed: 3 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -66,12 +66,9 @@ fir::TBAATree::TBAATree(mlir::LLVM::TBAATypeDescriptorAttr anyAccess,
6666
mlir::LLVM::TBAATypeDescriptorAttr dataRoot,
6767
mlir::LLVM::TBAATypeDescriptorAttr boxMemberTypeDesc)
6868
: targetDataTree(dataRoot.getContext(), "target data", dataRoot),
69-
globalDataTree(dataRoot.getContext(), "global data",
70-
targetDataTree.getRoot()),
71-
allocatedDataTree(dataRoot.getContext(), "allocated data",
72-
targetDataTree.getRoot()),
69+
globalDataTree(dataRoot.getContext(), "global data", dataRoot),
70+
allocatedDataTree(dataRoot.getContext(), "allocated data", dataRoot),
7371
dummyArgDataTree(dataRoot.getContext(), "dummy arg data", dataRoot),
74-
directDataTree(dataRoot.getContext(), "direct data",
75-
targetDataTree.getRoot()),
72+
directDataTree(dataRoot.getContext(), "direct data", dataRoot),
7673
anyAccessDesc(anyAccess), boxMemberTypeDesc(boxMemberTypeDesc),
7774
anyDataTypeDesc(dataRoot) {}

‎flang/lib/Optimizer/Transforms/AddAliasTags.cpp‎

Lines changed: 16 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -692,8 +692,9 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
692692
LLVM_DEBUG(llvm::dbgs().indent(2)
693693
<< "Found reference to dummy argument at " << *op << "\n");
694694
std::string name = getFuncArgName(llvm::cast<mlir::Value>(source.origin.u));
695-
// If it is a TARGET or POINTER, then we do not care about the name,
696-
// because the tag points to the root of the subtree currently.
695+
// POINTERS can alias with any POINTER or TARGET. Assume that TARGET dummy
696+
// arguments might alias with each other (because of the "TARGET" hole for
697+
// dummy arguments). See flang/docs/Aliasing.md.
697698
if (source.isTargetOrPointer()) {
698699
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
699700
} else if (!name.empty()) {
@@ -716,7 +717,12 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
716717
<< "Found reference to global " << globalName.str() << " at "
717718
<< *op << "\n");
718719
if (source.isPointer()) {
720+
// Pointers can alias with any pointer or target.
719721
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
722+
} else if (source.isTarget()) {
723+
// Targets could alias with any pointer but not with each other.
724+
tag = state.getFuncTreeWithScope(func, scopeOp)
725+
.targetDataTree.getTag(globalName);
720726
} else {
721727
// In general, place the tags under the "global data" root.
722728
fir::TBAATree::SubtreeState *subTree =
@@ -776,9 +782,17 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
776782
const char *name = glbl.getRootReference().data();
777783
LLVM_DEBUG(llvm::dbgs().indent(2) << "Found reference to direct " << name
778784
<< " at " << *op << "\n");
785+
// Pointer can alias with any pointer or target so that gets the root.
779786
if (source.isPointer())
780787
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
788+
// Targets could alias with any pointer but not with each other so they
789+
// get their own node inside of the target data tree.
790+
else if (source.isTarget())
791+
tag = state.getFuncTreeWithScope(func, scopeOp)
792+
.targetDataTree.getTag(name);
781793
else
794+
// Boxes that are not pointers or targets cannot alias with those that
795+
// are. Put them under global data.
782796
tag = state.getFuncTreeWithScope(func, scopeOp)
783797
.directDataTree.getTag(name);
784798
} else {

‎flang/test/Driver/tco-test-gen.fir‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -77,13 +77,13 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
7777
// CHECK: llvm.cond_br %[[VAL_17]], ^bb2, ^bb3
7878
// CHECK: ^bb2:
7979

80-
// AA: llvm.store %[[VAL_15]], %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : i32, !llvm.ptr
80+
// AA: llvm.store %[[VAL_15]], %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : i32, !llvm.ptr
8181
// NOAA: llvm.store %[[VAL_15]], %{{.*}} : i32, !llvm.ptr
8282

8383
// AA: %[[VAL_18:.*]] = llvm.load %[[ARG0]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "dummy arg data/_QFtestEnum", members = {<#llvm.tbaa_type_desc<id = "dummy arg data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "dummy arg data/_QFtestEnum", members = {<#llvm.tbaa_type_desc<id = "dummy arg data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : !llvm.ptr -> i32
8484
// NOAA: %[[VAL_18:.*]] = llvm.load %[[ARG0]] : !llvm.ptr -> i32
8585

86-
// AA: %[[VAL_19:.*]] = llvm.load %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : !llvm.ptr -> i32
86+
// AA: %[[VAL_19:.*]] = llvm.load %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : !llvm.ptr -> i32
8787
// NOAA: %[[VAL_19:.*]] = llvm.load %{{.*}} : !llvm.ptr -> i32
8888

8989
// CHECK: %[[VAL_20:.*]] = llvm.add %[[VAL_18]], %[[VAL_19]] : i32
@@ -92,15 +92,15 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
9292

9393
// CHECK: %[[VAL_21:.*]] = llvm.trunc %[[VAL_10]] : i64 to i32
9494

95-
// AA: %[[VAL_22:.*]] = llvm.load %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : !llvm.ptr -> i32
95+
// AA: %[[VAL_22:.*]] = llvm.load %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : !llvm.ptr -> i32
9696
// NOAA: %[[VAL_22:.*]] = llvm.load %{{.*}} : !llvm.ptr -> i32
9797

9898
// CHECK: %[[VAL_23:.*]] = llvm.add %[[VAL_22]], %[[VAL_21]] overflow<nsw> : i32
9999
// CHECK: %[[VAL_24:.*]] = llvm.sub %[[VAL_16]], %{{.*}} : i64
100100
// CHECK: llvm.br ^bb1(%[[VAL_23]], %[[VAL_24]] : i32, i64)
101101
// CHECK: ^bb3:
102102

103-
// AA: llvm.store %[[VAL_15]], %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "target data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : i32, !llvm.ptr
103+
// AA: llvm.store %[[VAL_15]], %[[VAL_1]] {tbaa = [#llvm.tbaa_tag<base_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, access_type = <id = "allocated data/_QFtestEi", members = {<#llvm.tbaa_type_desc<id = "allocated data", members = {<#llvm.tbaa_type_desc<id = "any data access", members = {<#llvm.tbaa_type_desc<id = "any access", members = {<#llvm.tbaa_root<id = "Flang function root _QPtest">, 0>}>, 0>}>, 0>}>, 0>}>, offset = 0>]} : i32, !llvm.ptr
104104
// NOAA: llvm.store %[[VAL_15]], %{{.*}} : i32, !llvm.ptr
105105

106106
// CHECK: llvm.return

‎flang/test/Fir/tbaa-codegen2.fir‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -114,4 +114,3 @@ module attributes {fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.targ
114114
// CHECK: ![[TMP_DATA_ACCESS_TAG]] = !{![[TMP_DATA_ACCESS_TYPE:.*]], ![[TMP_DATA_ACCESS_TYPE]], i64 0}
115115
// CHECK: ![[TMP_DATA_ACCESS_TYPE]] = !{!"allocated data/", ![[TMP_ACCESS_TYPE:.*]], i64 0}
116116
// CHECK: ![[TMP_ACCESS_TYPE]] = !{!"allocated data", ![[TARGET_ACCESS_TAG:.*]], i64 0}
117-
// CHECK: ![[TARGET_ACCESS_TAG]] = !{!"target data", ![[DATA_ACCESS_TYPE]], i64 0}

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