[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.

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: 351105

1 files changed, 32 insertions, 0 deletions

diff --git a/clang/test/CodeGen/catch-alignment-assumption-openmp.cpp b/clang/test/CodeGen/catch-alignment-assumption-openmp.cpp
new file mode 100644
index 00000000000..6d75ee0858d
--- /dev/null
+++ b/clang/test/CodeGen/catch-alignment-assumption-openmp.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -fopenmp-simd -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fopenmp-simd -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 -fopenmp-simd -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 -fopenmp-simd -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 30 }, {{.*}}* @[[CHAR]] }
+
+void func(char *data) {
+  // CHECK: define void @{{.*}}(i8* %[[DATA:.*]])
+  // CHECK-NEXT: [[ENTRY:.*]]:
+  // CHECK-NEXT:   %[[DATA_ADDR:.*]] = alloca i8*, align 8
+  // CHECK:   store i8* %[[DATA]], i8** %[[DATA_ADDR]], align 8
+  // CHECK:   %[[DATA_RELOADED:.*]] = load i8*, i8** %[[DATA_ADDR]], align 8
+  // CHECK-NEXT:   %[[PTRINT:.*]] = ptrtoint i8* %[[DATA_RELOADED]] to i64
+  // CHECK-NEXT:   %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 1073741823
+  // CHECK-NEXT:   %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[DATA_RELOADED]] 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 1073741824, 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 1073741824, 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]])
+
+#line 100
+#pragma omp for simd aligned(data : 0x40000000)
+  for (int x = 0; x < 1; x++)
+    data[x] = data[x];
+}