Re: [ros-dev] [ros-diffs] [hyperion] 38461: modified tests/pseh2/psehtest.c finally_13 test re-enabled, as it doesn't crash anymore finally_14 test fixed. Now we know how exceptions thrown in a __finally are supposed to be handled PSEH test suite now has 91 tests and passes all of them with both GCC and Visual C++
Just wanted to tell this is a great work, and with such test suite we will always notice if something breaks.
WBR, Aleksey Bragin.
On Dec 30, 2008, at 7:04 AM, hyperion@svn.reactos.org wrote:
Author: hyperion Date: Mon Dec 29 22:04:51 2008 New Revision: 38461
URL: http://svn.reactos.org/svn/reactos?rev=38461&view=rev Log: modified tests/pseh2/psehtest.c finally_13 test re-enabled, as it doesn't crash anymore finally_14 test fixed. Now we know how exceptions thrown in a __finally are supposed to be handled PSEH test suite now has 91 tests and passes all of them with both GCC and Visual C++
About the SEH tests. The tests are nice, but there are 2 things that makes me think the tests are cheating.
1.) All used variables are static. That means the optimizer is mostly out of the game. Is this planned to be a requirement (static or volatile variables)? 2.) The tests use return_positive() and return_zero() functions. Another way to stop the optimizer from doing his work, because function calls act as sequence points and the result isn't known at compile time. But this is far from practical. If you replace them with compiler constants, the optimizer will try to remove these assignmnents if possible.
So I did some testing. After removing the static, I got 1 error: psehtest.c:2490: Test failed: test_continue_search_3 failed
After replacing the return_x, ... functions with macros I got 3 errors: psehtest.c:2486: Test failed: test_continue_search_6 failed psehtest.c:2486: Test failed: test_execute_handler_12 failed psehtest.c:2486: Test failed: test_continue_execution_12 failed
Same with full and normal optimisation.
Timo
Aleksey Bragin schrieb:
Just wanted to tell this is a great work, and with such test suite we will always notice if something breaks.
WBR, Aleksey Bragin.
On Dec 30, 2008, at 7:04 AM, hyperion@svn.reactos.org wrote:
Author: hyperion Date: Mon Dec 29 22:04:51 2008 New Revision: 38461
URL: http://svn.reactos.org/svn/reactos?rev=38461&view=rev Log: modified tests/pseh2/psehtest.c finally_13 test re-enabled, as it doesn't crash anymore finally_14 test fixed. Now we know how exceptions thrown in a __finally are supposed to be handled PSEH test suite now has 91 tests and passes all of them with both GCC and Visual C++
Ros-dev mailing list Ros-dev@reactos.org http://www.reactos.org/mailman/listinfo/ros-dev
Timo Kreuzer wrote:
1.) All used variables are static. That means the optimizer is mostly out of the game.
It's intentional. Using functions instead of constants is intentional, too. Ensures variables are actually instanced, even if they are "unused". And PSEH macros have slightly different behavior when compile-time constants are used in some places. I'm unsure how to test *reliably* interactions between optimizer bugs and PSEH
So I did some testing. After removing the static, I got 1 error: psehtest.c:2490: Test failed: test_continue_search_3 failed
The return value of return_positive() is not stored anywhere, and ret remains uninitialized. Congratulations! you found a compiler bug
After replacing the return_x, ... functions with macros I got 3 errors:
I don't. Send me your modifications
KJK::Hyperion wrote:
Timo Kreuzer wrote:
1.) All used variables are static. That means the optimizer is mostly out of the game.
It's intentional. Using functions instead of constants is intentional, too. Ensures variables are actually instanced, even if they are "unused". And PSEH macros have slightly different behavior when compile-time constants are used in some places. I'm unsure how to test *reliably* interactions between optimizer bugs and PSEH
I just suggest testing real situations instead of hypothetical situations. And it's a fact that we normally don't use static variables and bot only functions but also constants in our code. So these tests are of small value regarding the usage in reactos. And you shouldn't simply blame the optmimizer to have bugs when it doesn't do what you would like it to do.
So I did some testing. After removing the static, I got 1 error: psehtest.c:2490: Test failed: test_continue_search_3 failed
The return value of return_positive() is not stored anywhere, and ret remains uninitialized. Congratulations! you found a compiler bug
No, it's a valid optimisation: 1. The return value of return_positive() is stored in edx 2. The code branches into the 1st try and except block 2a) except block (will not be called here): edx is put on the stack, return_arg() is called and the result copied to ebx 2b) try block: again 2 different branches, in both of them return_zero() is called and the result stored in ebx 3.) ebx is compared to the return value of return_positive()
The compiler generates a new instance of the ret variable each time it's assigned and it's free to use different registers and/or memory locations each time, as long as it stays consistent for each possible code path.
The test fails, because when executing the exception block, edx doesn't contain what it should, as it's zeroed in the try block before the exception happens. Exceptions are simply not considered as possible code pathes. This can and will happen unless a) We require that all variables that are changed inside a try block and referenced inside the except block must be declared volatile b) We find a way to tell gcc to not change the location of a variable during a try block.
After replacing the return_x, ... functions with macros I got 3 errors:
I don't. Send me your modifications
I attached 2 patches.
Regards, Timo
Index: psehtest.c =================================================================== --- psehtest.c (Revision 38469) +++ psehtest.c (Arbeitskopie) @@ -66,6 +66,39 @@
#define DEFINE_TEST(NAME_) static int test_ ## NAME_(void)
+#if 0 + +#define no_op() +#define return_arg(i) (i) + +#define return_zero() (0) +#define return_positive() (1234) +#define return_negative() (-1234) +#define return_one() (1) +#define return_minusone() (-1) + +#define return_zero_2(p) (0) +#define return_positive_2(p) (1234) +#define return_negative_2(p) (-1234) +#define return_one_2(p) (1) +#define return_minusone_2(p) (-1) + +#define return_zero_3(i) (0) +#define return_positive_3(i) (1234) +#define return_negative_3(i) (-1234) +#define return_one_3(i) (1) +#define return_minusone_3(i) (-1) + +#define return_zero_4(p, i) (0) +#define return_positive_4(p, i) (1234) +#define return_negative_4(p, i) (-1234) +#define return_one_4(p, i) (1) +#define return_minusone_4(p, i) (-1) + +#define set_positive(p) (*(p))=1 + +#endif + /* Empty statements *///{{{ DEFINE_TEST(empty_1) { @@ -119,7 +152,7 @@ /* Static exception filters *///{{{ DEFINE_TEST(execute_handler_1) { - static int ret; + int ret;
ret = return_zero();
@@ -139,7 +172,7 @@
DEFINE_TEST(continue_execution_1) { - static int ret; + int ret;
ret = return_zero();
@@ -159,7 +192,7 @@
DEFINE_TEST(continue_search_1) { - static int ret; + int ret;
ret = return_zero();
@@ -187,7 +220,7 @@
DEFINE_TEST(execute_handler_2) { - static int ret; + int ret;
ret = return_zero();
@@ -207,7 +240,7 @@
DEFINE_TEST(continue_execution_2) { - static int ret; + int ret;
ret = return_zero();
@@ -229,7 +262,7 @@ /* Dynamic exception filters *///{{{ DEFINE_TEST(execute_handler_3) { - static int ret; + int ret;
ret = return_zero();
@@ -249,7 +282,7 @@
DEFINE_TEST(continue_execution_3) { - static int ret; + int ret;
ret = return_zero();
@@ -269,7 +302,7 @@
DEFINE_TEST(continue_search_2) { - static int ret; + int ret;
ret = return_zero();
@@ -297,7 +330,7 @@
DEFINE_TEST(execute_handler_4) { - static int ret; + int ret;
ret = return_zero();
@@ -317,7 +350,7 @@
DEFINE_TEST(continue_execution_4) { - static int ret; + int ret;
ret = return_zero();
@@ -339,7 +372,7 @@ /* Dynamic exception filters, using _SEH2_GetExceptionInformation() *///{{{ DEFINE_TEST(execute_handler_5) { - static int ret; + int ret;
ret = return_zero();
@@ -359,7 +392,7 @@
DEFINE_TEST(continue_execution_5) { - static int ret; + int ret;
ret = return_zero();
@@ -379,7 +412,7 @@
DEFINE_TEST(continue_search_3) { - static int ret; + int ret;
ret = return_positive();
@@ -407,7 +440,7 @@
DEFINE_TEST(execute_handler_6) { - static int ret; + int ret;
ret = return_zero();
@@ -427,7 +460,7 @@
DEFINE_TEST(continue_execution_6) { - static int ret; + int ret;
ret = return_zero();
@@ -449,7 +482,7 @@ /* Dynamic exception filters, using _SEH2_GetExceptionCode() *///{{{ DEFINE_TEST(execute_handler_7) { - static int ret; + int ret;
ret = return_zero();
@@ -469,7 +502,7 @@
DEFINE_TEST(continue_execution_7) { - static int ret; + int ret;
ret = return_zero();
@@ -489,7 +522,7 @@
DEFINE_TEST(continue_search_4) { - static int ret; + int ret;
ret = return_zero();
@@ -517,7 +550,7 @@
DEFINE_TEST(execute_handler_8) { - static int ret; + int ret;
ret = return_zero();
@@ -537,7 +570,7 @@
DEFINE_TEST(continue_execution_8) { - static int ret; + int ret;
ret = return_zero();
@@ -559,7 +592,7 @@ /* Dynamic exception filters, using _SEH2_GetExceptionInformation() and _SEH2_GetExceptionCode() *///{{{ DEFINE_TEST(execute_handler_9) { - static int ret; + int ret;
ret = return_zero();
@@ -579,7 +612,7 @@
DEFINE_TEST(continue_execution_9) { - static int ret; + int ret;
ret = return_zero();
@@ -599,7 +632,7 @@
DEFINE_TEST(continue_search_5) { - static int ret; + int ret;
ret = return_zero();
@@ -627,7 +660,7 @@
DEFINE_TEST(execute_handler_10) { - static int ret; + int ret;
ret = return_zero();
@@ -647,7 +680,7 @@
DEFINE_TEST(continue_execution_10) { - static int ret; + int ret;
ret = return_zero();
@@ -669,7 +702,7 @@ /* Constant exception filters with side effects *///{{{ DEFINE_TEST(execute_handler_11) { - static int ret; + int ret;
ret = return_zero();
@@ -689,7 +722,7 @@
DEFINE_TEST(continue_execution_11) { - static int ret; + int ret;
ret = return_zero();
@@ -709,8 +742,8 @@
DEFINE_TEST(continue_search_6) { - static int ret; - static int ret2; + int ret; + int ret2;
ret = return_zero(); ret2 = return_zero(); @@ -742,7 +775,7 @@
DEFINE_TEST(execute_handler_12) { - static int ret; + int ret;
ret = return_zero();
@@ -762,7 +795,7 @@
DEFINE_TEST(continue_execution_12) { - static int ret; + int ret;
ret = return_zero();
@@ -784,7 +817,7 @@ /* _SEH2_LEAVE *///{{{ DEFINE_TEST(leave_1) { - static int ret; + int ret;
ret = return_zero();
@@ -805,7 +838,7 @@
DEFINE_TEST(leave_2) { - static int ret; + int ret;
ret = return_zero();
@@ -828,7 +861,7 @@
DEFINE_TEST(leave_3) { - static int ret; + int ret;
ret = return_zero();
@@ -852,7 +885,7 @@
DEFINE_TEST(leave_4) { - static int ret; + int ret;
ret = return_zero();
@@ -883,7 +916,7 @@
DEFINE_TEST(leave_5) { - static int ret; + int ret;
ret = return_zero();
@@ -909,7 +942,7 @@
DEFINE_TEST(leave_6) { - static int ret; + int ret;
ret = return_zero();
@@ -1106,7 +1139,7 @@ /* Termination blocks *///{{{ DEFINE_TEST(finally_1) { - static int ret; + int ret;
ret = return_zero();
@@ -1125,7 +1158,7 @@
DEFINE_TEST(finally_2) { - static int ret; + int ret;
ret = return_zero();
@@ -1145,7 +1178,7 @@
DEFINE_TEST(finally_3) { - static int ret; + int ret;
ret = return_zero();
@@ -1191,7 +1224,7 @@
DEFINE_TEST(finally_5) { - static int ret; + int ret;
ret = return_zero();
@@ -1219,7 +1252,7 @@
DEFINE_TEST(finally_6) { - static int ret; + int ret;
ret = return_zero();
@@ -1248,7 +1281,7 @@
DEFINE_TEST(finally_7) { - static int ret; + int ret;
ret = return_zero();
@@ -1278,7 +1311,7 @@
DEFINE_TEST(finally_8) { - static int ret; + int ret;
ret = return_zero();
@@ -1344,7 +1377,7 @@
DEFINE_TEST(finally_10) { - static int ret; + int ret;
ret = return_zero();
@@ -1382,7 +1415,7 @@
DEFINE_TEST(finally_11) { - static int ret; + int ret;
ret = return_zero();
@@ -1420,7 +1453,7 @@
DEFINE_TEST(finally_12) { - static int ret; + int ret;
ret = return_zero();
@@ -1494,7 +1527,7 @@
DEFINE_TEST(finally_13) { - static int ret; + int ret;
ret = return_zero();
@@ -1559,7 +1592,7 @@
DEFINE_TEST(finally_14) { - static int ret; + int ret;
ret = return_zero();
@@ -1601,7 +1634,7 @@
DEFINE_TEST(xpointers_1) { - static int ret; + int ret;
ret = return_zero();
@@ -1620,7 +1653,7 @@
DEFINE_TEST(xpointers_2) { - static int ret; + int ret;
ret = return_zero();
@@ -1639,8 +1672,8 @@
DEFINE_TEST(xpointers_3) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1659,8 +1692,8 @@
DEFINE_TEST(xpointers_4) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1679,8 +1712,8 @@
DEFINE_TEST(xpointers_5) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1699,8 +1732,8 @@
DEFINE_TEST(xpointers_6) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1719,7 +1752,7 @@
DEFINE_TEST(xpointers_7) { - static int ret; + int ret;
ret = return_zero();
@@ -1739,8 +1772,8 @@
DEFINE_TEST(xpointers_8) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1760,8 +1793,8 @@
DEFINE_TEST(xpointers_9) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1781,8 +1814,8 @@
DEFINE_TEST(xpointers_10) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1802,8 +1835,8 @@
DEFINE_TEST(xpointers_11) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1823,7 +1856,7 @@
DEFINE_TEST(xpointers_12) { - static int ret; + int ret;
ret = return_zero();
@@ -1850,8 +1883,8 @@
DEFINE_TEST(xpointers_13) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1878,8 +1911,8 @@
DEFINE_TEST(xpointers_14) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1906,8 +1939,8 @@
DEFINE_TEST(xpointers_15) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1934,8 +1967,8 @@
DEFINE_TEST(xpointers_16) { - static int ret; - static const ULONG_PTR args[] = { 1, 2, 12345 }; + int ret; + const ULONG_PTR args[] = { 1, 2, 12345 };
ret = return_zero();
@@ -1975,7 +2008,7 @@
DEFINE_TEST(xcode_1) { - static int ret; + int ret;
ret = return_zero();
@@ -1995,7 +2028,7 @@
DEFINE_TEST(xcode_2) { - static int ret; + int ret;
ret = return_zero();
@@ -2015,7 +2048,7 @@
DEFINE_TEST(xcode_3) { - static int ret; + int ret;
ret = return_zero();
@@ -2045,7 +2078,7 @@ /* _SEH2_AbnormalTermination() *///{{{ DEFINE_TEST(abnorm_1) { - static int ret; + int ret;
ret = return_zero();
@@ -2064,7 +2097,7 @@
DEFINE_TEST(abnorm_2) { - static int ret; + int ret;
ret = return_zero();
@@ -2083,7 +2116,7 @@
DEFINE_TEST(abnorm_3) { - static int ret; + int ret;
ret = return_zero();
@@ -2103,7 +2136,7 @@
DEFINE_TEST(abnorm_4) { - static int ret; + int ret;
ret = return_zero();
@@ -2131,7 +2164,7 @@
DEFINE_TEST(abnorm_5) { - static int ret; + int ret;
ret = return_zero();
@@ -2158,7 +2191,7 @@
DEFINE_TEST(abnorm_6) { - static int ret; + int ret;
ret = return_zero();
@@ -2185,7 +2218,7 @@
DEFINE_TEST(abnorm_7) { - static int ret; + int ret;
ret = return_zero();
@@ -2213,7 +2246,7 @@
DEFINE_TEST(abnorm_8) { - static int ret; + int ret;
ret = return_zero();
Index: psehtest.c =================================================================== --- psehtest.c (Revision 38469) +++ psehtest.c (Arbeitskopie) @@ -66,6 +66,39 @@
#define DEFINE_TEST(NAME_) static int test_ ## NAME_(void)
+#if 1 + +#define no_op() +#define return_arg(i) (i) + +#define return_zero() (0) +#define return_positive() (1234) +#define return_negative() (-1234) +#define return_one() (1) +#define return_minusone() (-1) + +#define return_zero_2(p) (0) +#define return_positive_2(p) (1234) +#define return_negative_2(p) (-1234) +#define return_one_2(p) (1) +#define return_minusone_2(p) (-1) + +#define return_zero_3(i) (0) +#define return_positive_3(i) (1234) +#define return_negative_3(i) (-1234) +#define return_one_3(i) (1) +#define return_minusone_3(i) (-1) + +#define return_zero_4(p, i) (0) +#define return_positive_4(p, i) (1234) +#define return_negative_4(p, i) (-1234) +#define return_one_4(p, i) (1) +#define return_minusone_4(p, i) (-1) + +#define set_positive(p) (*(p))=1 + +#endif + /* Empty statements *///{{{ DEFINE_TEST(empty_1) {
Timo Kreuzer wrote:
I just suggest testing real situations instead of hypothetical situations.
Every test tests a real situation I encountered during development of both PSEH 1 and PSEH 2 (infinite loops, stack misalignment, compilation failures, faulty logic, paths in library code that were never executed, compile-time constants with vs without side effects). Hypothetical situations are only situations that haven't happened yet
If you have tests to propose, propose tests
The return value of return_positive() is not stored anywhere, and ret remains uninitialized. Congratulations! you found a compiler bug
No, it's a valid optimisation:
_SEH2EnterFrame is marked returns_twice, GCC should ensure all register variables to be "dead" (i.e. copied to the stack frame) before calling it, and warn if they could be clobbered. Trusting the contents of a register after a call to _SEH2EnterFrame is a bug. Either that, or the gotos must be confusing GCC's flow control analysis. But the gotos are necessary for the pretty syntax, so we'll have to pay with yet more redundant code
After replacing the return_x, ... functions with macros I got 3 errors:
I don't. Send me your modifications
I attached 2 patches.
I believe this is what younger, ruder team members would refer to as "epic fail". Not me, of course. Me, I just wish I wasn't expected to find bugs in my bug reports
KJK::Hyperion schrieb:
Every test tests a real situation I encountered during development of both PSEH 1 and PSEH 2 (infinite loops, stack misalignment, compilation failures, faulty logic, paths in library code that were never executed, compile-time constants with vs without side effects). Hypothetical situations are only situations that haven't happened yet
If you have tests to propose, propose tests
Ok these test are fine to test that everything works as it should under some save assumptions. I suggest adding tests that cover fully optimized code. Non-volatile variables, constants, lots of code needing multiple registers in the try and except block, inline functions, inline assembly, etc... Everything that might be used anywhere in our code and might be totally clobbered by the optimizer.
The return value of return_positive() is not stored anywhere, and ret remains uninitialized. Congratulations! you found a compiler bug
No, it's a valid optimisation:
_SEH2EnterFrame is marked returns_twice, GCC should ensure all register variables to be "dead" (i.e. copied to the stack frame) before calling it, and warn if they could be clobbered. Trusting the contents of a register after a call to _SEH2EnterFrame is a bug. Either that, or the gotos must be confusing GCC's flow control analysis. But the gotos are necessary for the pretty syntax, so we'll have to pay with yet more redundant code
The gotos are not "confusing" gcc. SEH2EnterFrame isn't called in the first except branch, so the compiler is free to keep ret in any register it likes during that branch. The try branch has no need to keep ret in any memory location or register at all, because it's not referenced any more. It's only set to the result of return_zero(). It wouldn't make sense to store the old result as it will be droped anyway. In other words the register *is dead* on entering the try branch. Sorry, but you still didn't find a compiler bug.
After replacing the return_x, ... functions with macros I got 3 errors:
I don't. Send me your modifications
I attached 2 patches.
I believe this is what younger, ruder team members would refer to as "epic fail". Not me, of course. Me, I just wish I wasn't expected to find bugs in my bug reports
Lol, ok, I'd call it a typo ;-)
Timo Kreuzer wrote:
In other words the register *is dead* on entering the try branch.
Read and compare the disassembled code of continue_search_3 before and after my last change
KJK::Hyperion schrieb:
Timo Kreuzer wrote:
In other words the register *is dead* on entering the try branch.
Read and compare the disassembled code of continue_search_3 before and after my last change
Yes, it's fixed now. At least this case. It's still not the holy grail I think.
What about this one:
DEFINE_TEST(set_before_exception) { int ret1, ret2;
ret2 = ret1 = 0;
_SEH2_TRY { ret2 = 1; volatile char * p = 0; *p = 0; ret1 = 1; } _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER) { ret1 = -1; } _SEH2_END;
return (ret1 == -1 && ret2 == 1); }
The compiler assumes that on entering the except block, that not a single instruction of the try block has been executed. And it will use this to optimize away everything it can. MSVC will preserve the instruction order and make sure all variables are stored in memory locations. I don't think you can get this handled equally without hacking it into gcc.
This case isn't that bad. We just have the following requirement: Do not make any assumptions about the order in which code is executed inside the try block! Not even if normally you could say that something must be executed in a special order (like x = func1(); y = func2(x);)
But there's another thing that bothers me. It's guaranteed that all variables that are used after the call to _SEH2EnterFrame are either constants or stored in a memory location at the time that SEH2EnterFrame is called. No more, no less. It is not guaranteed that the variables stay there. Now the compiler could decide to move a variable into a register directly after the call (maybe because it's needed in this register in both branches) and before the branch. Then in the try branch later it's moved into another register just before the exception occurs.
Now this is hypothetical, because I couldn't find a real situation where this happens. I just think it might be possible.
Regards, Timo
Timo Kreuzer wrote:
This case isn't that bad. We just have the following requirement: Do not make any assumptions about the order in which code is executed inside the try block! Not even if normally you could say that something must be executed in a special order (like x = func1(); y = func2(x);)
Functions are called in the order you expect, unless the compiler is able to analyze/inline them (such as static/inline functions) or unless the code is written in a manner where the order is not defined by the specification of the language (e.g. multiple calls to functions in arguments for a function call). Anything the compiler doesn't know at compile-time won't be re-ordered. This applies to all optimizers (link-time optimizations may allow to re-order them though).
Thomas
Timo Kreuzer wrote:
Yes, it's fixed now. At least this case. It's still not the holy grail I think.
Fix it then
The compiler assumes that on entering the except block, that not a single instruction of the try block has been executed.
This is a reasonable assumption. It's also the same identical thing that happened with PSEH 1. A __try is supposed to imply barriers around any instruction, because any instruction could throw. We can't do that. The best we can do is make critical variables volatile, which implies a barrier in every access to them
I don't think you can get this handled equally without hacking it into gcc.
No, you think I should use a nested function for __except bodies but, for some reason, you prefer not to share this notion with me
-
Aleksey Bragin -
KJK::Hyperion -
Thomas Bluemel -
Timo Kreuzer