[flang][TBAA] refine TARGET/POINTER encoding #169544

tblah · 2025-11-25T18:31:45Z

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.

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. 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 fond no functional regressions in the gfortran test suite, fujitsu test suite, spec2017, or a selection of HPC apps we test internally.

llvmbot · 2025-11-25T18:32:21Z

@llvm/pr-subscribers-flang-fir-hlfir

@llvm/pr-subscribers-flang-driver

Author: Tom Eccles (tblah)

Changes

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.

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.

Patch is 68.42 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/169544.diff

14 Files Affected:

(modified) flang/include/flang/Optimizer/Analysis/TBAAForest.h (+19-5)
(modified) flang/lib/Optimizer/Analysis/TBAAForest.cpp (+3-6)
(modified) flang/lib/Optimizer/Transforms/AddAliasTags.cpp (+17-1)
(modified) flang/test/Driver/tco-test-gen.fir (+4-4)
(modified) flang/test/Fir/tbaa-codegen2.fir (-1)
(modified) flang/test/Transforms/tbaa-for-common-vars.fir (+11-18)
(modified) flang/test/Transforms/tbaa-for-global-equiv-vars.fir (+2-4)
(modified) flang/test/Transforms/tbaa-for-local-vars.fir (+18-14)
(modified) flang/test/Transforms/tbaa-with-dummy-scope.fir (+13-12)
(modified) flang/test/Transforms/tbaa-with-dummy-scope2.fir (+15-17)
(modified) flang/test/Transforms/tbaa.fir (+2-1)
(modified) flang/test/Transforms/tbaa2.fir (+9-11)
(modified) flang/test/Transforms/tbaa3.fir (+51-50)
(modified) flang/test/Transforms/tbaa4.fir (+13-19)

diff --git a/flang/include/flang/Optimizer/Analysis/TBAAForest.h b/flang/include/flang/Optimizer/Analysis/TBAAForest.h
index b4932594114a1..2d07058331288 100644
--- a/flang/include/flang/Optimizer/Analysis/TBAAForest.h
+++ b/flang/include/flang/Optimizer/Analysis/TBAAForest.h
@@ -99,11 +99,25 @@ struct TBAATree {
   //   |- "any data access"
   //      |
   //      |- "dummy arg data"
-  //      |- "target data"
-  //         |
-  //         |- "allocated data"
-  //         |- "direct data"
-  //         |- "global data"
+  //        |
+  //        |- <dummy arg name 1>
+  //        |- <dummy arg name 2>
+  //      |- "target data" <-- Any POINTER variable goes here
+  //        |
+  //        |- <target name 1> <--- any TARGET variable goes here
+  //        |- <target name 2>
+  //      |- "allocated data"
+  //        |
+  //        |- <allocated name 1>
+  //        |- <allocated name 2>
+  //      |- "direct data"
+  //        |
+  //        |- <direct name 1>
+  //        |- <direct name 2>
+  //      |- "global data"
+  //        |
+  //        |- <global name 1>
+  //        |- <global name 2>
   static TBAATree buildTree(mlir::StringAttr functionName);
 
 private:
diff --git a/flang/lib/Optimizer/Analysis/TBAAForest.cpp b/flang/lib/Optimizer/Analysis/TBAAForest.cpp
index 44a0348da3a6f..7154785c62c75 100644
--- a/flang/lib/Optimizer/Analysis/TBAAForest.cpp
+++ b/flang/lib/Optimizer/Analysis/TBAAForest.cpp
@@ -66,12 +66,9 @@ fir::TBAATree::TBAATree(mlir::LLVM::TBAATypeDescriptorAttr anyAccess,
                         mlir::LLVM::TBAATypeDescriptorAttr dataRoot,
                         mlir::LLVM::TBAATypeDescriptorAttr boxMemberTypeDesc)
     : targetDataTree(dataRoot.getContext(), "target data", dataRoot),
-      globalDataTree(dataRoot.getContext(), "global data",
-                     targetDataTree.getRoot()),
-      allocatedDataTree(dataRoot.getContext(), "allocated data",
-                        targetDataTree.getRoot()),
+      globalDataTree(dataRoot.getContext(), "global data", dataRoot),
+      allocatedDataTree(dataRoot.getContext(), "allocated data", dataRoot),
       dummyArgDataTree(dataRoot.getContext(), "dummy arg data", dataRoot),
-      directDataTree(dataRoot.getContext(), "direct data",
-                     targetDataTree.getRoot()),
+      directDataTree(dataRoot.getContext(), "direct data", dataRoot),
       anyAccessDesc(anyAccess), boxMemberTypeDesc(boxMemberTypeDesc),
       anyDataTypeDesc(dataRoot) {}
diff --git a/flang/lib/Optimizer/Transforms/AddAliasTags.cpp b/flang/lib/Optimizer/Transforms/AddAliasTags.cpp
index 0221c7a8184d7..990ef26e43035 100644
--- a/flang/lib/Optimizer/Transforms/AddAliasTags.cpp
+++ b/flang/lib/Optimizer/Transforms/AddAliasTags.cpp
@@ -694,8 +694,11 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
     std::string name = getFuncArgName(llvm::cast<mlir::Value>(source.origin.u));
     // If it is a TARGET or POINTER, then we do not care about the name,
     // because the tag points to the root of the subtree currently.
-    if (source.isTargetOrPointer()) {
+    if (source.isPointer()) {
       tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
+    } else if (source.isTarget()) {
+      tag =
+          state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag(name);
     } else if (!name.empty()) {
       tag = state.getFuncTreeWithScope(func, scopeOp)
                 .dummyArgDataTree.getTag(name);
@@ -716,7 +719,12 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
                << "Found reference to global " << globalName.str() << " at "
                << *op << "\n");
     if (source.isPointer()) {
+      // Pointers can alias with any pointer or target.
       tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
+    } else if (source.isTarget()) {
+      // Targets could alias with any pointer but not with eachother.
+      tag = state.getFuncTreeWithScope(func, scopeOp)
+                .targetDataTree.getTag(globalName);
     } else {
       // In general, place the tags under the "global data" root.
       fir::TBAATree::SubtreeState *subTree =
@@ -776,9 +784,17 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
       const char *name = glbl.getRootReference().data();
       LLVM_DEBUG(llvm::dbgs().indent(2) << "Found reference to direct " << name
                                         << " at " << *op << "\n");
+      // Pointer can alias with any pointer or target so that gets the root.
       if (source.isPointer())
         tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
+      // Targets could alias with any pointer but not with eachother so they get
+      // their own node inside of the target data tree.
+      else if (source.isTarget())
+        tag = state.getFuncTreeWithScope(func, scopeOp)
+                  .targetDataTree.getTag(name);
       else
+        // Boxes that are not pointers or targets cannot alias with those that
+        // are. Put them under global data.
         tag = state.getFuncTreeWithScope(func, scopeOp)
                   .directDataTree.getTag(name);
     } else {
diff --git a/flang/test/Driver/tco-test-gen.fir b/flang/test/Driver/tco-test-gen.fir
index b39295d72918f..438804ce42b76 100644
--- a/flang/test/Driver/tco-test-gen.fir
+++ b/flang/test/Driver/tco-test-gen.fir
@@ -77,13 +77,13 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
 // CHECK:           llvm.cond_br %[[VAL_17]], ^bb2, ^bb3
 // CHECK:         ^bb2:
 
-// 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
+// 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
 // NOAA:            llvm.store %[[VAL_15]], %{{.*}} : i32, !llvm.ptr
 
 // 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
 // NOAA:            %[[VAL_18:.*]] = llvm.load %[[ARG0]] : !llvm.ptr -> i32
 
-// 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
+// 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
 // NOAA:            %[[VAL_19:.*]] = llvm.load %{{.*}} : !llvm.ptr -> i32
 
 // CHECK:           %[[VAL_20:.*]] = llvm.add %[[VAL_18]], %[[VAL_19]] : i32
@@ -92,7 +92,7 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
 
 // CHECK:           %[[VAL_21:.*]] = llvm.trunc %[[VAL_10]] : i64 to i32
 
-// 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
+// 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
 // NOAA:            %[[VAL_22:.*]] = llvm.load %{{.*}} : !llvm.ptr -> i32
 
 // CHECK:           %[[VAL_23:.*]] = llvm.add %[[VAL_22]], %[[VAL_21]] overflow<nsw> : i32
@@ -100,7 +100,7 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
 // CHECK:           llvm.br ^bb1(%[[VAL_23]], %[[VAL_24]] : i32, i64)
 // CHECK:         ^bb3:
 
-// 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
+// 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
 // NOAA:            llvm.store %[[VAL_15]], %{{.*}} : i32, !llvm.ptr
 
 // CHECK:           llvm.return
diff --git a/flang/test/Fir/tbaa-codegen2.fir b/flang/test/Fir/tbaa-codegen2.fir
index 4907aa03ec5a5..071d3ec89394c 100644
--- a/flang/test/Fir/tbaa-codegen2.fir
+++ b/flang/test/Fir/tbaa-codegen2.fir
@@ -114,4 +114,3 @@ module attributes {fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", llvm.targ
 // CHECK: ![[TMP_DATA_ACCESS_TAG]] = !{![[TMP_DATA_ACCESS_TYPE:.*]], ![[TMP_DATA_ACCESS_TYPE]], i64 0}
 // CHECK: ![[TMP_DATA_ACCESS_TYPE]] = !{!"allocated data/", ![[TMP_ACCESS_TYPE:.*]], i64 0}
 // CHECK: ![[TMP_ACCESS_TYPE]] = !{!"allocated data", ![[TARGET_ACCESS_TAG:.*]], i64 0}
-// CHECK: ![[TARGET_ACCESS_TAG]] = !{!"target data", ![[DATA_ACCESS_TYPE]], i64 0}
diff --git a/flang/test/Transforms/tbaa-for-common-vars.fir b/flang/test/Transforms/tbaa-for-common-vars.fir
index a8dd86bff72ed..087e6938f8acb 100644
--- a/flang/test/Transforms/tbaa-for-common-vars.fir
+++ b/flang/test/Transforms/tbaa-for-common-vars.fir
@@ -28,8 +28,7 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4
 // CHECK: #[[$ATTR_0:.+]] = #llvm.tbaa_root<id = "Flang function root _QPtest1">
 // CHECK: #[[$ATTR_1:.+]] = #llvm.tbaa_type_desc<id = "any access", members = {<#[[$ATTR_0]], 0>}>
 // CHECK: #[[$ATTR_2:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[$ATTR_1]], 0>}>
-// CHECK: #[[$ATTR_3:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[$ATTR_2]], 0>}>
-// CHECK: #[[$ATTR_4:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[$ATTR_3]], 0>}>
+// CHECK: #[[$ATTR_4:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[$ATTR_2]], 0>}>
 // CHECK: #[[$ATTR_5:.+]] = #llvm.tbaa_type_desc<id = "global data/common1_", members = {<#[[$ATTR_4]], 0>}>
 // CHECK: #[[$ATTR_6:.+]] = #llvm.tbaa_type_desc<id = "global data/common1_/bytes_4_to_7", members = {<#[[$ATTR_5]], 0>}>
 // CHECK: #[[$ATTR_7:.+]] = #llvm.tbaa_type_desc<id = "global data/common1_/bytes_0_to_3", members = {<#[[$ATTR_5]], 0>}>
@@ -66,8 +65,7 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4
 // CHECK: #[[$ATTR_10:.+]] = #llvm.tbaa_root<id = "Flang function root _QPtest2">
 // CHECK: #[[$ATTR_11:.+]] = #llvm.tbaa_type_desc<id = "any access", members = {<#[[$ATTR_10]], 0>}>
 // CHECK: #[[$ATTR_12:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[$ATTR_11]], 0>}>
-// CHECK: #[[$ATTR_13:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[$ATTR_12]], 0>}>
-// CHECK: #[[$ATTR_14:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[$ATTR_13]], 0>}>
+// CHECK: #[[$ATTR_14:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[$ATTR_12]], 0>}>
 // CHECK: #[[$ATTR_15:.+]] = #llvm.tbaa_type_desc<id = "global data/common2_", members = {<#[[$ATTR_14]], 0>}>
 // CHECK: #[[$ATTR_16:.+]] = #llvm.tbaa_type_desc<id = "global data/common2_/bytes_0_to_3", members = {<#[[$ATTR_15]], 0>}>
 // CHECK: #[[$ATTR_18:.+]] = #llvm.tbaa_tag<base_type = #[[$ATTR_16]], access_type = #[[$ATTR_16]], offset = 0>
@@ -118,14 +116,13 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4
 // CHECK: #[[ANYACC3INNER:.+]] = #llvm.tbaa_type_desc<id = "any access", members = {<#[[ROOT3INNER]], 0>}>
 // CHECK: #[[ANYDATA3:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[ANYACC3]], 0>}>
 // CHECK: #[[ANYDATA3INNER:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[ANYACC3INNER]], 0>}>
-// CHECK: #[[TARGETDATA3:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[ANYDATA3]], 0>}>
+// CHECK: #[[GLOBALDATA3:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[ANYDATA3]], 0>}>
 // CHECK: #[[DUMMYARG3INNER:.+]] = #llvm.tbaa_type_desc<id = "dummy arg data", members = {<#[[ANYDATA3INNER]], 0>}>
-// CHECK: #[[GLOBALDATA3:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[TARGETDATA3]], 0>}>
+// CHECK: #[[GLOBALDATA3COMMON3:.+]] = #llvm.tbaa_type_desc<id = "global data/common3_", members = {<#[[GLOBALDATA3]], 0>}>
 // CHECK: #[[DUMMYD:.+]] = #llvm.tbaa_type_desc<id = "dummy arg data/_QFtest3FinnerEd", members = {<#[[DUMMYARG3INNER]], 0>}>
 // CHECK: #[[DUMMYC:.+]] = #llvm.tbaa_type_desc<id = "dummy arg data/_QFtest3FinnerEc", members = {<#[[DUMMYARG3INNER]], 0>}>
 // CHECK: #[[DUMMYDTAG:.+]] = #llvm.tbaa_tag<base_type = #[[DUMMYD]], access_type = #[[DUMMYD]], offset = 0>
 // CHECK: #[[DUMMYCTAG:.+]] = #llvm.tbaa_tag<base_type = #[[DUMMYC]], access_type = #[[DUMMYC]], offset = 0>
-// CHECK: #[[GLOBALDATA3COMMON3:.+]] = #llvm.tbaa_type_desc<id = "global data/common3_", members = {<#[[GLOBALDATA3]], 0>}>
 // CHECK: #[[GLOBALB:.+]] = #llvm.tbaa_type_desc<id = "global data/common3_/bytes_4_to_7", members = {<#[[GLOBALDATA3COMMON3]], 0>}>
 // CHECK: #[[GLOBALA:.+]] = #llvm.tbaa_type_desc<id = "global data/common3_/bytes_0_to_3", members = {<#[[GLOBALDATA3COMMON3]], 0>}>
 // CHECK: #[[GLOBALBTAG:.+]] = #llvm.tbaa_tag<base_type = #[[GLOBALB]], access_type = #[[GLOBALB]], offset = 0>
@@ -180,10 +177,8 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4
 // CHECK: #[[INNER4ANYACC:.+]] = #llvm.tbaa_type_desc<id = "any access", members = {<#[[INNER4ROOT]], 0>}>
 // CHECK: #[[TEST4ANYDATA:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[TEST4ANYCC]], 0>}>
 // CHECK: #[[INNER4ANYDATA:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[INNER4ANYACC]], 0>}>
-// CHECK: #[[TEST4TARGET:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[TEST4ANYDATA]], 0>}>
-// CHECK: #[[INNER4TARGET:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[INNER4ANYDATA]], 0>}>
-// CHECK: #[[TEST4GLOBAL:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[TEST4TARGET]], 0>}>
-// CHECK: #[[INNER4GLOBAL:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[INNER4TARGET]], 0>}>
+// CHECK: #[[TEST4GLOBAL:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[TEST4ANYDATA]], 0>}>
+// CHECK: #[[INNER4GLOBAL:.+]] = #llvm.tbaa_type_desc<id = "global data", members = {<#[[INNER4ANYDATA]], 0>}>
 // CHECK: #[[TEST4COMMON:.+]] = #llvm.tbaa_type_desc<id = "global data/common4_", members = {<#[[TEST4GLOBAL]], 0>}>
 // CHECK: #[[INNER4COMMON:.+]] = #llvm.tbaa_type_desc<id = "global data/common4_", members = {<#[[INNER4GLOBAL]], 0>}>
 // CHECK: #[[TEST4B:.+]] = #llvm.tbaa_type_desc<id = "global data/common4_/bytes_4_to_7", members = {<#[[TEST4COMMON]], 0>}>
@@ -229,8 +224,7 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<!llvm.ptr = dense<64> : vector<4
 // CHECK: #[[TEST5ROOT:.+]] = #llvm.tbaa_root<id = "Flang function root _QPtest5">
 // CHECK: #[[TEST5ANYACC:.+]] = #llvm.tbaa_type_desc<id = "any access", members = {<#[[TEST5ROOT]], 0>}>
 // CHECK: #[[TEST5ANYDATA:.+]] = #llvm.tbaa_type_desc<id = "any data access", members = {<#[[TEST5ANYACC]], 0>}>
-// CHECK: #[[TEST5TARGET:.+]] = #llvm.tbaa_type_desc<id = "target data", members = {<#[[TEST5ANYDATA]], ...
[truncated]

tblah · 2025-11-25T18:33:44Z

~~To do: dummy targets might alias with each other as if they are pointers.~~
Edit: done

vzakhari

Thank you for the changes, Tom!

I wonder whether it is ever possible for ip to alias with rt or even it2.

I believe you can alias ip with it2 using ip => it2(index).

Aliasing ip with rt does not seem possible to me, though complex pointer/target variables may alias with real pointer variables (e.g. when %re or %im part designator is used in pointer assignment).

vzakhari · 2025-11-26T01:36:59Z

flang/include/flang/Optimizer/Analysis/TBAAForest.h

+  //        |
+  //        |- <dummy arg name 1>
+  //        |- <dummy arg name 2>
+  //      |- "target data" <-- Any POINTER variable goes here


As we discussed offline, the TARGET dummy arguments should also point to the root of "target data".

flang/lib/Optimizer/Transforms/AddAliasTags.cpp

tblah · 2025-11-26T17:36:52Z

Thanks for taking a look Slava, this is now ready for full review.

For the applications and benchmarks I measured, this patch did not make any measurable change to performance. This is unsurprising because many of these (e.g. spec2017) are well studied so I expect we would have already noticed if something like this were missing.

However, this change is expected to help for a benchmark in a future version of SPEC.

jeanPerier

Thanks Tom, your change makes sense to me. Please still wait for Slava's approval.

vzakhari

Thank you, Tom!

vzakhari · 2025-11-26T22:40:08Z

It just hit me. I think the following code is correct, so a global may alias with TARGET dummy:

module mod
  real :: glob
contains
  subroutine s1
    glob = 0.0
    call s2(glob)
  end subroutine s1
  subroutine s2(x)
    real, target :: x
    glob = 1.0
    print *, x
  end subroutine s2
end module mod

program main
  use mod
  call s1
end program main

eugeneepshteyn · 2025-11-26T22:52:36Z

It just hit me. I think the following code is correct, so a global may alias with TARGET dummy:

Is it correct, though? Wouldn't it violate "15.5.2.14 Restrictions on entities associated with dummy arguments"?

vzakhari · 2025-11-26T23:03:14Z

It just hit me. I think the following code is correct, so a global may alias with TARGET dummy:

Is it correct, though? Wouldn't it violate "15.5.2.14 Restrictions on entities associated with dummy arguments"?

You may be right, Eugene! It looks like exception (b) does not apply here.

jeanPerier · 2025-11-27T09:58:51Z

You may be right, Eugene! It looks like exception (b) does not apply here.

Agree with Eugene and I tested similar case with and array assignment that shows gfortran optimize this case:

module m
 ! If TARGET is added here, the assignment in test should not be optimized.
 integer :: x(10) = [(i, i=1,10)]
contains
subroutine test(y)
 integer, target :: y(:)
 x = y
end subroutine
end module

 use m
  call test(x(10:1:-1))
  print *, x
 end

tblah · 2025-11-27T10:59:36Z

Thanks all. I have updated the PR description with the standard reference.

I will wait until after thanksgiving to merge this in case it leads to any unforeseen regressions.

tblah requested review from DominikAdamski, Renaud-K, jeanPerier and vzakhari November 25, 2025 18:31

llvmbot added flang:driver flang Flang issues not falling into any other category flang:fir-hlfir labels Nov 25, 2025

tblah marked this pull request as draft November 25, 2025 18:32

tblah changed the title ~~[flang][TBAA] refine TARGET/POINTER encoding~~ DRAFT: [flang][TBAA] refine TARGET/POINTER encoding Nov 25, 2025

vzakhari reviewed Nov 26, 2025

View reviewed changes

TARGET dummy args can alias

8829176

tblah marked this pull request as ready for review November 26, 2025 17:33

tblah changed the title ~~DRAFT: [flang][TBAA] refine TARGET/POINTER encoding~~ [flang][TBAA] refine TARGET/POINTER encoding Nov 26, 2025

jeanPerier approved these changes Nov 26, 2025

View reviewed changes

vzakhari approved these changes Nov 26, 2025

View reviewed changes

[flang][TBAA] refine TARGET/POINTER encoding #169544

Are you sure you want to change the base?

[flang][TBAA] refine TARGET/POINTER encoding #169544

Conversation

tblah commented Nov 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

llvmbot commented Nov 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

tblah commented Nov 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

vzakhari left a comment

Choose a reason for hiding this comment

Uh oh!

vzakhari Nov 26, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

tblah commented Nov 26, 2025

Uh oh!

jeanPerier left a comment

Choose a reason for hiding this comment

Uh oh!

vzakhari left a comment

Choose a reason for hiding this comment

Uh oh!

vzakhari commented Nov 26, 2025

Uh oh!

eugeneepshteyn commented Nov 26, 2025

Uh oh!

vzakhari commented Nov 26, 2025

Uh oh!

jeanPerier commented Nov 27, 2025

Uh oh!

tblah commented Nov 27, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

tblah commented Nov 25, 2025 •

edited

Loading

llvmbot commented Nov 25, 2025 •

edited

Loading

tblah commented Nov 25, 2025 •

edited

Loading