[clang] [Clang] Fix crash in __builtin_assume_aligned (PR #114217)

[Oliver Stannard via cfe-commits]

https://github.com/ostannard updated https://github.com/llvm/llvm-project/pull/114217

>From a657d11051c95473727ca5e9f6a8e8ab195fe590 Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Wed, 30 Oct 2024 12:01:56 +0000
Subject: [PATCH 1/3] [Clang] Fix crash in __builtin_assume_aligned

The CodeGen for __builtin_assume_aligned assumes that the first argument
is a pointer, so crashes if the int-conversion error is downgraded or
disabled. Emit a non-downgradable error if the argument is not a
pointer, like we currently do for __builtin_launder.

Fixes #110914.
---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 ++
 clang/lib/Sema/SemaChecking.cpp                  | 5 ++++-
 clang/test/Sema/builtin-assume-aligned.c         | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 34ff49d7238a7f..67ef5fcae142c2 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -12271,6 +12271,8 @@ def warn_noderef_to_dereferenceable_pointer : Warning<
 def err_builtin_launder_invalid_arg : Error<
   "%select{non-pointer|function pointer|void pointer}0 argument to "
   "'__builtin_launder' is not allowed">;
+def err_builtin_assume_aligned_invalid_arg : Error<
+  "non-pointer argument to '__builtin_assume_aligned' is not allowed">;
 
 def err_builtin_is_within_lifetime_invalid_arg : Error<
   "%select{non-|function }0pointer argument to '__builtin_is_within_lifetime' "
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 3308b898a5b68f..f6f67895973cc7 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -5272,8 +5272,11 @@ bool Sema::BuiltinAssumeAligned(CallExpr *TheCall) {
   {
     ExprResult FirstArgResult =
         DefaultFunctionArrayLvalueConversion(FirstArg);
-    if (checkBuiltinArgument(*this, TheCall, 0))
+    if (!FirstArgResult.get()->getType()->isPointerType()) {
+      Diag(TheCall->getBeginLoc(), diag::err_builtin_assume_aligned_invalid_arg)
+          << TheCall->getSourceRange();
       return true;
+    }
     /// In-place updation of FirstArg by checkBuiltinArgument is ignored.
     TheCall->setArg(0, FirstArgResult.get());
   }
diff --git a/clang/test/Sema/builtin-assume-aligned.c b/clang/test/Sema/builtin-assume-aligned.c
index 33e85578451529..57378a3426524a 100644
--- a/clang/test/Sema/builtin-assume-aligned.c
+++ b/clang/test/Sema/builtin-assume-aligned.c
@@ -74,7 +74,7 @@ int test13(int *a) {
 }
 
 int test14(int *a, int b) {
-  a = (int *)__builtin_assume_aligned(b, 32); // expected-error {{incompatible integer to pointer conversion passing 'int' to parameter of type 'const void *}}
+  a = (int *)__builtin_assume_aligned(b, 32); // expected-error {{non-pointer argument to '__builtin_assume_aligned' is not allowed}}
 }
 
 int test15(int *b) {

>From fe68409901a3415aade3a20a0baf35b4be3c6d2e Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Wed, 18 Dec 2024 11:13:13 +0000
Subject: [PATCH 2/3] Remove obsolete comment

---
 clang/lib/Sema/SemaChecking.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index f35d170f993910..cd8ad126269f07 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -5325,7 +5325,6 @@ bool Sema::BuiltinAssumeAligned(CallExpr *TheCall) {
           << TheCall->getSourceRange();
       return true;
     }
-    /// In-place updation of FirstArg by checkBuiltinArgument is ignored.
     TheCall->setArg(0, FirstArgResult.get());
   }
 

>From fed607e33f6edfd77afb086366c19c5a90cf392f Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard at arm.com>
Date: Wed, 18 Dec 2024 11:13:34 +0000
Subject: [PATCH 3/3] Add test

---
 clang/test/Sema/builtin-assume-aligned-downgrade.c | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 clang/test/Sema/builtin-assume-aligned-downgrade.c

diff --git a/clang/test/Sema/builtin-assume-aligned-downgrade.c b/clang/test/Sema/builtin-assume-aligned-downgrade.c
new file mode 100644
index 00000000000000..93631e73643737
--- /dev/null
+++ b/clang/test/Sema/builtin-assume-aligned-downgrade.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fsyntax-only -Wno-int-conversion -triple x86_64-linux -verify %s
+
+// Check that the pointer->int conversion error is not downgradable for the
+// pointer argument to __builtin_assume_aligned.
+
+int test(int *a, int b) {
+  a = (int *)__builtin_assume_aligned(b, 32); // expected-error {{non-pointer argument to '__builtin_assume_aligned' is not allowed}}
+  int *y = __builtin_assume_aligned(1, 1); // expected-error {{non-pointer argument to '__builtin_assume_aligned' is not allowed}}
+}