[PtrAuth] Add ConstantPtrAuth comparator to FunctionComparator.cpp #159480
+120
−0
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
|
@llvm/pr-subscribers-llvm-transforms Author: Oskar Wirga (oskarwirga) ChangesWhen building rustc std for arm64e, core fails to compile successfully with the error: This is a result of function merging so I modified FunctionComparator.cpp as the ConstantPtrAuth value would go unchecked in the switch statement. The test case is a reduction from the failure in core and fails on main with: Full diff: https://github.com/llvm/llvm-project/pull/159480.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/FunctionComparator.cpp b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
index 6d4026e8209de..4148ac9d4442d 100644
--- a/llvm/lib/Transforms/Utils/FunctionComparator.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionComparator.cpp
@@ -353,6 +353,19 @@ int FunctionComparator::cmpConstants(const Constant *L,
return 1;
if (!L->isNullValue() && R->isNullValue())
return -1;
+
+ // Handle authenticated pointer constants produced by ConstantPtrAuth::get.
+ if (auto *PA1 = dyn_cast<ConstantPtrAuth>(L)) {
+ auto *PA2 = dyn_cast<ConstantPtrAuth>(R);
+ if (!PA2)
+ return cmpNumbers(L->getValueID(), R->getValueID());
+
+ if (int Res = cmpConstants(PA1->getPointer(), PA2->getPointer()))
+ return Res;
+ if (int Res = cmpConstants(PA1->getKey(), PA2->getKey()))
+ return Res;
+ return cmpConstants(PA1->getDiscriminator(), PA2->getDiscriminator());
+ }
auto GlobalValueL = const_cast<GlobalValue *>(dyn_cast<GlobalValue>(L));
auto GlobalValueR = const_cast<GlobalValue *>(dyn_cast<GlobalValue>(R));
diff --git a/llvm/test/Transforms/MergeFunc/ptrauth-const-compare.ll b/llvm/test/Transforms/MergeFunc/ptrauth-const-compare.ll
new file mode 100644
index 0000000000000..75ebb834c6219
--- /dev/null
+++ b/llvm/test/Transforms/MergeFunc/ptrauth-const-compare.ll
@@ -0,0 +1,67 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --include-generated-funcs --version 2
+;; Check the case for ConstantPtrAuth to be compared properly in FunctionComparator.cpp
+; RUN: opt -S -passes=mergefunc < %s | FileCheck %s
+target triple = "arm64e-apple-ios14.0.0"
+
+define { ptr, i64 } @"foo"() {
+start:
+ %func = alloca [8 x i8], align 8
+ br i1 false, label %bb5, label %bb9
+
+bb9: ; preds = %bb2, %start
+ %self = load i8, ptr null, align 1
+ br i1 false, label %bb2, label %bb5
+
+bb5: ; preds = %bb9, %start
+ ret { ptr, i64 } zeroinitializer
+
+bb2: ; preds = %bb9
+ call void ptrauth (ptr null, i32 0)(ptr null, i8 0)
+ br label %bb9
+}
+
+define { ptr, i64 } @"bar"() {
+start:
+ %func = alloca [8 x i8], align 8
+ br i1 false, label %bb5, label %bb9
+
+bb9: ; preds = %bb2, %start
+ %self = load i8, ptr null, align 1
+ br i1 false, label %bb2, label %bb5
+
+bb5: ; preds = %bb9, %start
+ ret { ptr, i64 } zeroinitializer
+
+bb2: ; preds = %bb9
+ call void ptrauth (ptr @"baz", i32 0)(ptr null, i8 0)
+ br label %bb9
+}
+
+declare void @"baz"()
+; CHECK-LABEL: define { ptr, i64 } @foo() {
+; CHECK-NEXT: start:
+; CHECK-NEXT: [[FUNC:%.*]] = alloca [8 x i8], align 8
+; CHECK-NEXT: br i1 false, label [[BB5:%.*]], label [[BB9:%.*]]
+; CHECK: bb9:
+; CHECK-NEXT: [[SELF:%.*]] = load i8, ptr null, align 1
+; CHECK-NEXT: br i1 false, label [[BB2:%.*]], label [[BB5]]
+; CHECK: bb5:
+; CHECK-NEXT: ret { ptr, i64 } zeroinitializer
+; CHECK: bb2:
+; CHECK-NEXT: call void ptrauth (ptr null, i32 0)(ptr null, i8 0)
+; CHECK-NEXT: br label [[BB9]]
+;
+;
+; CHECK-LABEL: define { ptr, i64 } @bar() {
+; CHECK-NEXT: start:
+; CHECK-NEXT: [[FUNC:%.*]] = alloca [8 x i8], align 8
+; CHECK-NEXT: br i1 false, label [[BB5:%.*]], label [[BB9:%.*]]
+; CHECK: bb9:
+; CHECK-NEXT: [[SELF:%.*]] = load i8, ptr null, align 1
+; CHECK-NEXT: br i1 false, label [[BB2:%.*]], label [[BB5]]
+; CHECK: bb5:
+; CHECK-NEXT: ret { ptr, i64 } zeroinitializer
+; CHECK: bb2:
+; CHECK-NEXT: call void ptrauth (ptr @baz, i32 0)(ptr null, i8 0)
+; CHECK-NEXT: br label [[BB9]]
+;
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
oskarwirga
force-pushed
the
arm64e-rust-fixes
branch
from
66cb663 to
095255e
Compare
asl
reviewed
Sep 17, 2025
asl
reviewed
Sep 17, 2025
oskarwirga
force-pushed
the
arm64e-rust-fixes
branch
from
095255e to
10f5e77
Compare
kovdan01
reviewed
Sep 29, 2025
oskarwirga
force-pushed
the
arm64e-rust-fixes
branch
from
10f5e77 to
c9cf318
Compare
|
@ahmedbougacha I think you're better looking at this one |
|
In a call instruction like this call void ptrauth (ptr @baz, i32 0)(ptr null)a signed pointer to This is probably acceptable in this kind of tests (except for that I'm not sure if calling signed null pointer in call void @callee(ptr ptrauth (ptr @baz, i32 0))This way, |
When building rustc std for arm64e, the optimizations result in devirtualization of indirect calls. This can happen during function merging so I modified FunctionComparator.cpp as the ConstantPtrAuth value would go unchecked in the switch statement.
oskarwirga
force-pushed
the
arm64e-rust-fixes
branch
from
c9cf318 to
a79f5dc
Compare
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.
When building rustc std for arm64e, core fails to compile successfully with the error:
This is a result of function merging so I modified FunctionComparator.cpp as the ConstantPtrAuth value would go unchecked in the switch statement.
The test case is a reduction from the failure in core and fails on main with: