[CodeGen] Add TBAA struct path info for array members #137719
+47
−6
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Avoid unintentional matches against extra load/stores in the unoptimized LLVM IR.
This enables the LLVM optimizer to view accesses to distinct struct
members as independent, also for array members. For example, the
following two stores no longer alias:
struct S { int a[10]; int b; };
void test(S *p, int i) {
p->a[i] = ...;
p->b = ...;
}
Array members were already added to TBAA struct type nodes in commit
57493e2. Here, we extend a path tag for an array subscript expression.
llvmbot
added
clang
|
@llvm/pr-subscribers-clang-codegen Author: Bruno De Fraine (brunodf-snps) ChangesThis enables the LLVM optimizer to view accesses to distinct struct Array members were already added to TBAA struct type nodes in commit Full diff: https://github.com/llvm/llvm-project/pull/137719.diff 2 Files Affected:
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index bba7d1e805f3f..c95a54fcebba9 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4503,7 +4503,32 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
E->getType(), !getLangOpts().PointerOverflowDefined, SignedIndices,
E->getExprLoc(), &arrayType, E->getBase());
EltBaseInfo = ArrayLV.getBaseInfo();
- EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
+ if (!CGM.getCodeGenOpts().NewStructPathTBAA) {
+ // Since CodeGenTBAA::getTypeInfoHelper only handles array types for
+ // new struct path TBAA, we must a use a plain access.
+ EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
+ } else if (ArrayLV.getTBAAInfo().isMayAlias()) {
+ EltTBAAInfo = TBAAAccessInfo::getMayAliasInfo();
+ } else if (ArrayLV.getTBAAInfo().isIncomplete()) {
+ EltTBAAInfo = CGM.getTBAAAccessInfo(E->getType());
+ } else {
+ // Extend struct path from base lvalue, similar to EmitLValueForField.
+ // If no base type has been assigned for the array access, then try to
+ // generate one.
+ EltTBAAInfo = ArrayLV.getTBAAInfo();
+ if (!EltTBAAInfo.BaseType) {
+ EltTBAAInfo.BaseType = CGM.getTBAABaseTypeInfo(ArrayLV.getType());
+ assert(!EltTBAAInfo.Offset &&
+ "Nonzero offset for an access with no base type!");
+ }
+ // The index into the array is a runtime value. We use the same struct
+ // path for all array elements (that of the element at index 0). So we
+ // set the access type and size, but do not have to adjust
+ // EltTBAAInfo.Offset.
+ EltTBAAInfo.AccessType = CGM.getTBAATypeInfo(E->getType());
+ EltTBAAInfo.Size =
+ getContext().getTypeSizeInChars(E->getType()).getQuantity();
+ }
} else {
// The base must be a pointer; emit it with an estimate of its alignment.
Addr = EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
diff --git a/clang/test/CodeGen/tbaa-array.cpp b/clang/test/CodeGen/tbaa-array.cpp
index 4a6576e2eeb7f..7cda1dd8d5bf7 100644
--- a/clang/test/CodeGen/tbaa-array.cpp
+++ b/clang/test/CodeGen/tbaa-array.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s \
+// RUN: %clang_cc1 -triple x86_64-linux -O1 %s \
// RUN: -emit-llvm -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s \
+// RUN: %clang_cc1 -triple x86_64-linux -O1 %s \
// RUN: -new-struct-path-tbaa -emit-llvm -o - | \
// RUN: FileCheck -check-prefix=CHECK-NEW %s
//
@@ -10,6 +10,8 @@
struct A { int i; };
struct B { A a[1]; };
struct C { int i; int x[3]; };
+struct D { int n; int arr[]; }; // flexible array member
+extern int AA[]; // incomplete array type
int foo(B *b) {
// CHECK-LABEL: _Z3fooP1B
@@ -28,16 +30,30 @@ int bar(C *c) {
int bar2(C *c) {
// CHECK-NEW-LABEL: _Z4bar2P1C
-// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_C_x:!.*]]
return c->x[2];
}
int bar3(C *c, int j) {
// CHECK-NEW-LABEL: _Z4bar3P1Ci
-// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_C_x]]
return c->x[j];
}
+int bar4(D *d) {
+// CHECK-NEW-LABEL: _Z4bar4P1D
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+ return d->arr[d->n];
+}
+
+int bar5(int j) {
+// CHECK-NEW-LABEL: _Z4bar5i
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+ return AA[2] + AA[j];
+}
+
// CHECK-DAG: [[TAG_A_i]] = !{[[TYPE_A:!.*]], [[TYPE_int:!.*]], i64 0}
// CHECK-DAG: [[TYPE_A]] = !{!"_ZTS1A", !{{.*}}, i64 0}
// CHECK-DAG: [[TYPE_int]] = !{!"int", !{{.*}}, i64 0}
@@ -45,8 +61,8 @@ int bar3(C *c, int j) {
// CHECK-NEW-DAG: [[TYPE_char:!.*]] = !{{{.*}}, i64 1, !"omnipotent char"}
// CHECK-NEW-DAG: [[TYPE_int:!.*]] = !{[[TYPE_char]], i64 4, !"int"}
// CHECK-NEW-DAG: [[TAG_int]] = !{[[TYPE_int]], [[TYPE_int]], i64 0, i64 4}
-// CHECK-NEW-DAG: [[TYPE_pointer:!.*]] = !{[[TYPE_char]], i64 8, !"any pointer"}
// CHECK-NEW-DAG: [[TYPE_A:!.*]] = !{[[TYPE_char]], i64 4, !"_ZTS1A", [[TYPE_int]], i64 0, i64 4}
// CHECK-NEW-DAG: [[TAG_A_i]] = !{[[TYPE_A]], [[TYPE_int]], i64 0, i64 4}
// CHECK-NEW-DAG: [[TYPE_C:!.*]] = !{[[TYPE_char]], i64 16, !"_ZTS1C", [[TYPE_int]], i64 0, i64 4, [[TYPE_int]], i64 4, i64 12}
// CHECK-NEW-DAG: [[TAG_C_i]] = !{[[TYPE_C:!.*]], [[TYPE_int:!.*]], i64 0, i64 4}
+// CHECK-NEW-DAG: [[TAG_C_x]] = !{[[TYPE_C:!.*]], [[TYPE_int:!.*]], i64 4, i64 4}
|
|
@llvm/pr-subscribers-clang Author: Bruno De Fraine (brunodf-snps) ChangesThis enables the LLVM optimizer to view accesses to distinct struct Array members were already added to TBAA struct type nodes in commit Full diff: https://github.com/llvm/llvm-project/pull/137719.diff 2 Files Affected:
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index bba7d1e805f3f..c95a54fcebba9 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4503,7 +4503,32 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
E->getType(), !getLangOpts().PointerOverflowDefined, SignedIndices,
E->getExprLoc(), &arrayType, E->getBase());
EltBaseInfo = ArrayLV.getBaseInfo();
- EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
+ if (!CGM.getCodeGenOpts().NewStructPathTBAA) {
+ // Since CodeGenTBAA::getTypeInfoHelper only handles array types for
+ // new struct path TBAA, we must a use a plain access.
+ EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
+ } else if (ArrayLV.getTBAAInfo().isMayAlias()) {
+ EltTBAAInfo = TBAAAccessInfo::getMayAliasInfo();
+ } else if (ArrayLV.getTBAAInfo().isIncomplete()) {
+ EltTBAAInfo = CGM.getTBAAAccessInfo(E->getType());
+ } else {
+ // Extend struct path from base lvalue, similar to EmitLValueForField.
+ // If no base type has been assigned for the array access, then try to
+ // generate one.
+ EltTBAAInfo = ArrayLV.getTBAAInfo();
+ if (!EltTBAAInfo.BaseType) {
+ EltTBAAInfo.BaseType = CGM.getTBAABaseTypeInfo(ArrayLV.getType());
+ assert(!EltTBAAInfo.Offset &&
+ "Nonzero offset for an access with no base type!");
+ }
+ // The index into the array is a runtime value. We use the same struct
+ // path for all array elements (that of the element at index 0). So we
+ // set the access type and size, but do not have to adjust
+ // EltTBAAInfo.Offset.
+ EltTBAAInfo.AccessType = CGM.getTBAATypeInfo(E->getType());
+ EltTBAAInfo.Size =
+ getContext().getTypeSizeInChars(E->getType()).getQuantity();
+ }
} else {
// The base must be a pointer; emit it with an estimate of its alignment.
Addr = EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
diff --git a/clang/test/CodeGen/tbaa-array.cpp b/clang/test/CodeGen/tbaa-array.cpp
index 4a6576e2eeb7f..7cda1dd8d5bf7 100644
--- a/clang/test/CodeGen/tbaa-array.cpp
+++ b/clang/test/CodeGen/tbaa-array.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s \
+// RUN: %clang_cc1 -triple x86_64-linux -O1 %s \
// RUN: -emit-llvm -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s \
+// RUN: %clang_cc1 -triple x86_64-linux -O1 %s \
// RUN: -new-struct-path-tbaa -emit-llvm -o - | \
// RUN: FileCheck -check-prefix=CHECK-NEW %s
//
@@ -10,6 +10,8 @@
struct A { int i; };
struct B { A a[1]; };
struct C { int i; int x[3]; };
+struct D { int n; int arr[]; }; // flexible array member
+extern int AA[]; // incomplete array type
int foo(B *b) {
// CHECK-LABEL: _Z3fooP1B
@@ -28,16 +30,30 @@ int bar(C *c) {
int bar2(C *c) {
// CHECK-NEW-LABEL: _Z4bar2P1C
-// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_C_x:!.*]]
return c->x[2];
}
int bar3(C *c, int j) {
// CHECK-NEW-LABEL: _Z4bar3P1Ci
-// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_C_x]]
return c->x[j];
}
+int bar4(D *d) {
+// CHECK-NEW-LABEL: _Z4bar4P1D
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+ return d->arr[d->n];
+}
+
+int bar5(int j) {
+// CHECK-NEW-LABEL: _Z4bar5i
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+// CHECK-NEW: load i32, {{.*}}, !tbaa [[TAG_int:!.*]]
+ return AA[2] + AA[j];
+}
+
// CHECK-DAG: [[TAG_A_i]] = !{[[TYPE_A:!.*]], [[TYPE_int:!.*]], i64 0}
// CHECK-DAG: [[TYPE_A]] = !{!"_ZTS1A", !{{.*}}, i64 0}
// CHECK-DAG: [[TYPE_int]] = !{!"int", !{{.*}}, i64 0}
@@ -45,8 +61,8 @@ int bar3(C *c, int j) {
// CHECK-NEW-DAG: [[TYPE_char:!.*]] = !{{{.*}}, i64 1, !"omnipotent char"}
// CHECK-NEW-DAG: [[TYPE_int:!.*]] = !{[[TYPE_char]], i64 4, !"int"}
// CHECK-NEW-DAG: [[TAG_int]] = !{[[TYPE_int]], [[TYPE_int]], i64 0, i64 4}
-// CHECK-NEW-DAG: [[TYPE_pointer:!.*]] = !{[[TYPE_char]], i64 8, !"any pointer"}
// CHECK-NEW-DAG: [[TYPE_A:!.*]] = !{[[TYPE_char]], i64 4, !"_ZTS1A", [[TYPE_int]], i64 0, i64 4}
// CHECK-NEW-DAG: [[TAG_A_i]] = !{[[TYPE_A]], [[TYPE_int]], i64 0, i64 4}
// CHECK-NEW-DAG: [[TYPE_C:!.*]] = !{[[TYPE_char]], i64 16, !"_ZTS1C", [[TYPE_int]], i64 0, i64 4, [[TYPE_int]], i64 4, i64 12}
// CHECK-NEW-DAG: [[TAG_C_i]] = !{[[TYPE_C:!.*]], [[TYPE_int:!.*]], i64 0, i64 4}
+// CHECK-NEW-DAG: [[TAG_C_x]] = !{[[TYPE_C:!.*]], [[TYPE_int:!.*]], i64 4, i64 4}
|
|
@kosarev @fhahn @rjmccall @efriedma-quic @hfinkel Note 1: I found the test tbaa-array.cpp was not always matching what it seems because the patterns would match local variable load/stores in the unoptimized LLVM IR. So I started with commit d63c8fe to switch to optimized LLVM IR (this could be precommitted). |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This enables the LLVM optimizer to view accesses to distinct struct
members as independent, also for array members. For example, the
following two stores no longer alias:
Array members were already added to TBAA struct type nodes in commit
57493e2. Here, we extend a path tag for an array subscript expression.