[clang][UBSan] Sanitization for alignment assumptions.
Summary:
UB isn't nice. It's cool and powerful, but not nice.
Having a way to detect it is nice though.
[[ https://wg21.link/p1007r3 | P1007R3: std::assume_aligned ]] / http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r2.pdf says:
```
We propose to add this functionality via a library function instead of a core language attribute.
...
If the pointer passed in is not aligned to at least N bytes, calling assume_aligned results in undefined behaviour.
```
This differential teaches clang to sanitize all the various variants of this assume-aligned attribute.
Requires D54588 for LLVM IRBuilder changes.
The compiler-rt part is D54590.
This is a second commit, the original one was r351105,
which was mass-reverted in r351159 because 2 compiler-rt tests were failing.
Reviewers: ABataev, craig.topper, vsk, rsmith, rnk, #sanitizers, erichkeane, filcab, rjmccall
Reviewed By: rjmccall
Subscribers: chandlerc, ldionne, EricWF, mclow.lists, cfe-commits, bkramer
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D54589
llvm-svn: 351177
diff --git a/clang/test/CodeGen/catch-alignment-assumption-attribute-assume_aligned-on-function.cpp b/clang/test/CodeGen/catch-alignment-assumption-attribute-assume_aligned-on-function.cpp
new file mode 100644
index 0000000..0b92ff6
--- /dev/null
+++ b/clang/test/CodeGen/catch-alignment-assumption-attribute-assume_aligned-on-function.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **__attribute__((assume_aligned(0x80000000))) passthrough(char **x) {
+ // CHECK: define i8** @[[PASSTHROUGH:.*]](i8** %[[X:.*]])
+ // CHECK-NEXT: entry:
+ // CHECK-NEXT: %[[X_ADDR:.*]] = alloca i8**, align 8
+ // CHECK-NEXT: store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+ // CHECK-NEXT: %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+ // CHECK-NEXT: ret i8** %[[X_RELOADED]]
+ // CHECK-NEXT: }
+ return x;
+}
+
+char **caller(char **x) {
+ // CHECK: define i8** @{{.*}}(i8** %[[X]])
+ // CHECK-NEXT: entry:
+ // CHECK-NEXT: %[[X_ADDR]] = alloca i8**, align 8
+ // CHECK-NEXT: store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+ // CHECK-NEXT: %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+ // CHECK-NEXT: %[[X_RETURNED:.*]] = call i8** @[[PASSTHROUGH]](i8** %[[X_RELOADED]])
+ // CHECK-NEXT: %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
+ // CHECK-NEXT: %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+ // CHECK-NEXT: %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+ // CHECK-SANITIZE-NEXT: %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
+ // CHECK-SANITIZE-NEXT: br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+ // CHECK-SANITIZE: [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+ // CHECK-SANITIZE-NORECOVER-NEXT: call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+ // CHECK-SANITIZE-RECOVER-NEXT: call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+ // CHECK-SANITIZE-TRAP-NEXT: call void @llvm.trap(){{.*}}, !nosanitize
+ // CHECK-SANITIZE-UNREACHABLE-NEXT: unreachable, !nosanitize
+ // CHECK-SANITIZE: [[CONT]]:
+ // CHECK-NEXT: call void @llvm.assume(i1 %[[MASKCOND]])
+ // CHECK-NEXT: ret i8** %[[X_RETURNED]]
+ // CHECK-NEXT: }
+#line 100
+ return passthrough(x);
+}