[llvm-commits] CVS: llvm/runtime/GCCLibraries/libexception/c++-exception.cpp c++-exception.h exception.h
Chris Lattner
lattner at cs.uiuc.edu
Thu Aug 28 15:00:01 PDT 2003
Changes in directory llvm/runtime/GCCLibraries/libexception:
c++-exception.cpp updated: 1.5 -> 1.6
c++-exception.h updated: 1.6 -> 1.7
exception.h updated: 1.3 -> 1.4
---
Log message:
* Add proper support for rethrown exceptions.
* Make catch_begin() produce a pointer that must be passed to catch_end()
* Eliminate the caught exception stack.
* Add optional debugging code that may be turned on.
---
Diffs of the changes:
Index: llvm/runtime/GCCLibraries/libexception/c++-exception.cpp
diff -u llvm/runtime/GCCLibraries/libexception/c++-exception.cpp:1.5 llvm/runtime/GCCLibraries/libexception/c++-exception.cpp:1.6
--- llvm/runtime/GCCLibraries/libexception/c++-exception.cpp:1.5 Thu Aug 28 09:35:52 2003
+++ llvm/runtime/GCCLibraries/libexception/c++-exception.cpp Thu Aug 28 14:58:51 2003
@@ -11,6 +11,12 @@
#include <cstdlib>
#include <cstdarg>
+//#define DEBUG
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
//===----------------------------------------------------------------------===//
// Generic exception support
//
@@ -18,7 +24,11 @@
// Thread local state for exception handling.
// FIXME: This should really be made thread-local!
//
-static llvm_exception *CaughtExceptionStack = 0;
+
+// LastCaughtException - The last exception caught by this handler. This is for
+// implementation of _rethrow and _get_last_caught.
+//
+static llvm_exception *LastCaughtException = 0;
// UncaughtExceptionStack - The stack of exceptions currently being thrown.
static llvm_exception *UncaughtExceptionStack = 0;
@@ -76,13 +86,9 @@
// exception.
//
static void cxx_destructor(llvm_exception *LE) /* might throw */{
+ assert(LE->Next == 0 && "On the uncaught stack??");
llvm_cxx_exception *E = get_cxx_exception(LE);
- // The exception is no longer caught.
- assert(CaughtExceptionStack == LE &&
- "Destroying an exception which is not the current caught exception?");
- CaughtExceptionStack = LE->Next;
-
struct ExceptionFreer {
void *Ptr;
ExceptionFreer(void *P) : Ptr(P) {}
@@ -110,6 +116,7 @@
E->BaseException.Next = UncaughtExceptionStack;
UncaughtExceptionStack = &E->BaseException;
E->BaseException.HandlerCount = 0;
+ E->BaseException.isRethrown = 0;
E->TypeInfo = (const std::type_info*)TypeInfoPtr;
E->ExceptionObjectDestructor = DtorPtr;
@@ -121,14 +128,16 @@
// CXXExceptionISA - use the type info object stored in the exception to see if
// TypeID matches and, if so, to adjust the exception object pointer.
//
-static void *CXXExceptionISA(llvm_cxx_exception *E, const std::type_info *Type){
+static void *CXXExceptionISA(llvm_cxx_exception *E,
+ const std::type_info *Type) throw() {
// ThrownPtr is a pointer to the object being thrown...
void *ThrownPtr = E+1;
const std::type_info *ThrownType = E->TypeInfo;
+#if 0
// FIXME: this code exists in the GCC exception handling library: I haven't
// thought about this yet, so it should be verified at some point!
-#if 1
+
// Pointer types need to adjust the actual pointer, not
// the pointer to pointer that is the exception object.
// This also has the effect of passing pointer types
@@ -137,8 +146,13 @@
ThrownPtr = *(void **)ThrownPtr;
#endif
- if (Type->__do_catch(ThrownType, &ThrownPtr, 1))
+ if (Type->__do_catch(ThrownType, &ThrownPtr, 1)) {
+#ifdef DEBUG
+ printf("isa<%s>(%s): 0x%p -> 0x%p\n", Type->name(), ThrownType->name(),
+ E+1, ThrownPtr);
+#endif
return ThrownPtr;
+ }
return 0;
}
@@ -175,11 +189,17 @@
UncaughtExceptionStack = E->Next;
// The exception is now caught.
- E->Next = CaughtExceptionStack;
- CaughtExceptionStack = E;
+ LastCaughtException = E;
+ E->Next = 0;
+ E->isRethrown = 0;
// Increment the handler count for this exception.
E->HandlerCount++;
+
+#ifdef DEBUG
+ printf("Exiting begin_catch Ex=0x%p HandlerCount=%d!\n", E+1,
+ E->HandlerCount);
+#endif
// Return a pointer to the raw exception object.
return E+1;
@@ -200,22 +220,44 @@
return ObjPtr;
}
+// __llvm_cxxeh_get_last_caught - Return the last exception that was caught by
+// ...begin_catch.
+//
+void *__llvm_cxxeh_get_last_caught() throw() {
+ assert(LastCaughtException && "No exception caught!!");
+ return LastCaughtException+1;
+}
// __llvm_cxxeh_end_catch - This function decrements the HandlerCount of the
// top-level caught exception, destroying it if this is the last handler for the
// exception.
//
-void __llvm_cxxeh_end_catch() /* might throw */ {
- llvm_exception *E = CaughtExceptionStack;
+void __llvm_cxxeh_end_catch(void *Ex) /* might throw */ {
+ llvm_exception *E = (llvm_exception*)Ex - 1;
assert(E && "There are no caught exceptions!");
// If this is the last handler using the exception, destroy it now!
- if (--E->HandlerCount == 0)
+ if (--E->HandlerCount == 0 && !E->isRethrown) {
+#ifdef DEBUG
+ printf("Destroying exception!\n");
+#endif
E->ExceptionDestructor(E); // Release memory for the exception
+ }
+#ifdef DEBUG
+ printf("Exiting end_catch Ex=0x%p HandlerCount=%d!\n", Ex, E->HandlerCount);
+#endif
}
+// __llvm_cxxeh_call_terminate - This function is called when the dtor for an
+// object being destroyed due to an exception throw throws an exception. This
+// is illegal because it would cause multiple exceptions to be active at one
+// time.
void __llvm_cxxeh_call_terminate() throw() {
- __terminate(__terminate_handler);
+ void (*Handler)(void) = __terminate_handler;
+ if (UncaughtExceptionStack)
+ if (UncaughtExceptionStack->ExceptionType == CXXException)
+ Handler = get_cxx_exception(UncaughtExceptionStack)->TerminateHandler;
+ __terminate(Handler);
}
@@ -225,19 +267,21 @@
// prepared to deal with foreign exceptions.
//
void __llvm_cxxeh_rethrow() throw() {
- llvm_exception *E = CaughtExceptionStack;
+ llvm_exception *E = LastCaughtException;
if (E == 0)
- // 15.1.8 - If there are no uncaught exceptions being thrown, 'throw;'
- // should call terminate.
+ // 15.1.8 - If there are no exceptions being thrown, 'throw;' should call
+ // terminate.
//
__terminate(__terminate_handler);
- // Otherwise we have an exception to rethrow. Move it back to the uncaught
- // stack.
- CaughtExceptionStack = E->Next;
+ // Otherwise we have an exception to rethrow. Mark the exception as such.
+ E->isRethrown = 1;
+
+ // Add the exception to the top of the uncaught stack, to preserve the
+ // invariant that the top of the uncaught stack is the current exception.
E->Next = UncaughtExceptionStack;
UncaughtExceptionStack = E;
-
+
// Return to the caller, which should perform the unwind now.
}
@@ -283,8 +327,8 @@
// Whatever exception this is, it is not allowed by the (empty) spec, call
// unexpected, according to 15.4.8.
try {
- __llvm_cxxeh_begin_catch(); // Start the catch
- __llvm_cxxeh_end_catch(); // Free the exception
+ void *Ex = __llvm_cxxeh_begin_catch(); // Start the catch
+ __llvm_cxxeh_end_catch(Ex); // Free the exception
__unexpected(__unexpected_handler);
} catch (...) {
// Any exception thrown by unexpected cannot match the ehspec. Call
@@ -307,10 +351,10 @@
// permitted to pass through) or not a C++ exception that is allowed. Kill
// the exception and call the unexpected handler.
try {
- __llvm_cxxeh_begin_catch(); // Start the catch
- __llvm_cxxeh_end_catch(); // Free the exception
+ void *Ex = __llvm_cxxeh_begin_catch(); // Start the catch
+ __llvm_cxxeh_end_catch(Ex); // Free the exception
} catch (...) {
- __terminate(__terminate_handler); // Exception dtor threw
+ __terminate(__terminate_handler); // Exception dtor threw
}
try {
Index: llvm/runtime/GCCLibraries/libexception/c++-exception.h
diff -u llvm/runtime/GCCLibraries/libexception/c++-exception.h:1.6 llvm/runtime/GCCLibraries/libexception/c++-exception.h:1.7
--- llvm/runtime/GCCLibraries/libexception/c++-exception.h:1.6 Thu Aug 28 09:43:36 2003
+++ llvm/runtime/GCCLibraries/libexception/c++-exception.h Thu Aug 28 14:58:51 2003
@@ -55,7 +55,7 @@
namespace __cxxabiv1 {
// Invokes given handler, dying appropriately if the user handler was
// so inconsiderate as to return.
- extern void __terminate(std::terminate_handler) __attribute__((noreturn));
+ extern void __terminate(std::terminate_handler) throw() __attribute__((noreturn));
extern void __unexpected(std::unexpected_handler) __attribute__((noreturn));
// The current installed user handlers.
@@ -74,8 +74,10 @@
throw();
void *__llvm_cxxeh_begin_catch() throw();
void *__llvm_cxxeh_begin_catch_if_isa(void *CatchType) throw();
- void __llvm_cxxeh_end_catch() /* might throw */;
+ void __llvm_cxxeh_end_catch(void *Exception) /* might throw */;
void __llvm_cxxeh_rethrow() throw();
+ void *__llvm_cxxeh_get_last_caught() throw();
+
void __llvm_cxxeh_check_eh_spec(void *Info, ...);
}
Index: llvm/runtime/GCCLibraries/libexception/exception.h
diff -u llvm/runtime/GCCLibraries/libexception/exception.h:1.3 llvm/runtime/GCCLibraries/libexception/exception.h:1.4
--- llvm/runtime/GCCLibraries/libexception/exception.h:1.3 Wed Aug 27 17:58:51 2003
+++ llvm/runtime/GCCLibraries/libexception/exception.h Thu Aug 28 14:58:51 2003
@@ -31,6 +31,14 @@
// falls to zero, the exception is destroyed.
//
unsigned HandlerCount;
+
+ // isRethrown - This field is set on an exception if it has been 'throw;'n.
+ // This is needed because the exception might exit through a number of the
+ // end_catch statements matching the number of begin_catch statements that
+ // have been processed. When this happens, the exception should become
+ // uncaught, not dead.
+ //
+ int isRethrown;
};
enum {
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