PowerPC's ABIs differ from those of other architectures in that the

callee-saved return address is stored in the caller's stack frame, not
the callee's.  This patch adjusts the logic to find the LR in the
correct place for PowerPC.

Patch joint with Bill Seurer.

llvm-svn: 243467

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.cc

@@ -83,7 +83,15 @@ void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
   while (IsValidFrame((uptr)frame, stack_top, bottom) &&
          IsAligned((uptr)frame, sizeof(*frame)) &&
          size < max_depth) {
+#ifdef __powerpc__
+    uhwptr *caller_frame = (uhwptr*)frame[0];
+    if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
+        !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
+      break;
+    uhwptr pc1 = caller_frame[2];
+#else
     uhwptr pc1 = frame[1];
+#endif
     if (pc1 != pc) {
       trace_buffer[size++] = (uptr) pc1;
     }

compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h

@@ -19,8 +19,7 @@ namespace __sanitizer {
 
 static const u32 kStackTraceMax = 256;
 
-#if SANITIZER_LINUX && (defined(__aarch64__) || defined(__powerpc__) || \
-                        defined(__powerpc64__) || defined(__sparc__) || \
+#if SANITIZER_LINUX && (defined(__aarch64__) || defined(__sparc__) || \
                         defined(__mips__))
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_WINDOWS