compiler-rt/lib/tsan: allow the Go runtime to return multiple stack f…

…rames for a single PC

This fix allows tsan to report stack traces correctly even in the
presence of mid-stack inlining by the Go compiler.

See golang/go#33309

lib/tsan/go/tsan_go.cpp

@@ -54,20 +54,33 @@ struct SymbolizeCodeContext {
 };
 
 SymbolizedStack *SymbolizeCode(uptr addr) {
-  SymbolizedStack *s = SymbolizedStack::New(addr);
-  SymbolizeCodeContext cbctx;
-  internal_memset(&cbctx, 0, sizeof(cbctx));
-  cbctx.pc = addr;
-  go_runtime_cb(CallbackSymbolizeCode, &cbctx);
-  if (cbctx.res) {
+  SymbolizedStack *first = SymbolizedStack::New(addr);
+  SymbolizedStack *s = first;
+  while(true) {
+    SymbolizeCodeContext cbctx;
+    internal_memset(&cbctx, 0, sizeof(cbctx));
+    cbctx.pc = addr;
+    go_runtime_cb(CallbackSymbolizeCode, &cbctx);
+    if (cbctx.res == 0) {
+      break;
+    }
     AddressInfo &info = s->info;
     info.module_offset = cbctx.off;
     info.function = internal_strdup(cbctx.func ? cbctx.func : "??");
     info.file = internal_strdup(cbctx.file ? cbctx.file : "-");
     info.line = cbctx.line;
     info.column = 0;
+
+    if (cbctx.pc == addr) { // outermost (non-inlined) function
+      break;
+    }
+    addr = cbctx.pc;
+    // Allocate a stack entry for the parent of the inlined function.
+    SymbolizedStack *s2 = SymbolizedStack::New(addr);
+    s->next = s2;
+    s = s2;
   }
-  return s;
+  return first;
 }
 
 struct SymbolizeDataContext {