[PATCH] D32517: [ubsan] Request the fast unwinder when print_stacktrace=1

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.

This makes it possible to get stacktrace info when print_stacktrace=1 on
Darwin (where the slow unwinder is not currently supported [1]). This
should not regress any other platforms (Windows will fall back to the
slow unwinder).

[1] The thread about r300295 has a relatively recent discusion about
this. We should be able to enable the existing slow unwind functionality
for Darwin, but this needs more testing.


https://reviews.llvm.org/D32517

Files:
  lib/ubsan/ubsan_diag.cc
  test/ubsan/TestCases/Misc/missing_return.cpp
  test/ubsan/TestCases/TypeCheck/misaligned.cpp


Index: test/ubsan/TestCases/TypeCheck/misaligned.cpp
===================================================================
--- test/ubsan/TestCases/TypeCheck/misaligned.cpp
+++ test/ubsan/TestCases/TypeCheck/misaligned.cpp
@@ -47,11 +47,8 @@
     // CHECK-LOAD-NEXT: {{^ 00 00 00 01 02 03 04  05}}
     // CHECK-LOAD-NEXT: {{^             \^}}
     return *p && 0;
-    // Slow stack unwinding is disabled on Darwin for now, see
-    // https://code.google.com/p/address-sanitizer/issues/detail?id=137
     // CHECK-Linux-STACK-LOAD: #0 {{.*}}main{{.*}}misaligned.cpp
-    // Check for the already checked line to avoid lit error reports.
-    // CHECK-Darwin-STACK-LOAD: {{ }}
+    // CHECK-Darwin-STACK-LOAD: #0 {{.*}}main{{.*}}misaligned.cpp
 
   case 's':
     // CHECK-STORE: misaligned.cpp:[[@LINE+4]]{{(:5)?}}: runtime error: store to misaligned address [[PTR:0x[0-9a-f]*]] for type 'int', which requires 4 byte alignment
Index: test/ubsan/TestCases/Misc/missing_return.cpp
===================================================================
--- test/ubsan/TestCases/Misc/missing_return.cpp
+++ test/ubsan/TestCases/Misc/missing_return.cpp
@@ -4,10 +4,9 @@
 
 // CHECK: missing_return.cpp:[[@LINE+1]]:5: runtime error: execution reached the end of a value-returning function without returning a value
 int f() {
-// Slow stack unwinding is not available on Darwin for now, see
-// https://code.google.com/p/address-sanitizer/issues/detail?id=137
-// CHECK-Linux-STACKTRACE: #0 {{.*}}f(){{.*}}missing_return.cpp:[[@LINE-3]]
-// CHECK-FreeBSD-STACKTRACE: #0 {{.*}}f(void){{.*}}missing_return.cpp:[[@LINE-4]]
+// CHECK-Linux-STACKTRACE: #0 {{.*}}f(){{.*}}missing_return.cpp:[[@LINE-1]]
+// CHECK-FreeBSD-STACKTRACE: #0 {{.*}}f(void){{.*}}missing_return.cpp:[[@LINE-2]]
+// CHECK-Darwin-STACKTRACE: #0 {{.*}}f(){{.*}}missing_return.cpp:[[@LINE-3]]
 }
 
 int main(int, char **argv) {
Index: lib/ubsan/ubsan_diag.cc
===================================================================
--- lib/ubsan/ubsan_diag.cc
+++ lib/ubsan/ubsan_diag.cc
@@ -31,15 +31,12 @@
   // will definitely be called when we print the first diagnostics message.
   if (!flags()->print_stacktrace)
     return;
-  // We can only use slow unwind, as we don't have any information about stack
-  // top/bottom.
-  // FIXME: It's better to respect "fast_unwind_on_fatal" runtime flag and
-  // fetch stack top/bottom information if we have it (e.g. if we're running
-  // under ASan).
-  if (StackTrace::WillUseFastUnwind(false))
-    return;
+
+  uptr top, bottom;
+  __sanitizer::GetThreadStackTopAndBottom(false, &top, &bottom);
   BufferedStackTrace stack;
-  stack.Unwind(kStackTraceMax, pc, bp, 0, 0, 0, false);
+  stack.Unwind(kStackTraceMax, pc, bp, nullptr, top, bottom,
+               /*request_fast_unwind=*/true);
   stack.Print();
 }
 


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