LDC 1.3 (1.2) ARMv5 issues #2058
Description
This is a continuation of #2024 (comment)
The issues so far observed are related to exception handling when compiled with optimizations turned on.
For example, compiling a simple test:
void main()
{
throw new Exception("");
}
ldc druntime and phobos compiled with -O2 or -O3
= Throwing new exception of type object.Exception: 0x402ff280 (struct at 0x4008c4ac, classinfo at 0x61980, 1 structs in flight)
- entering personality function. state: 0; ucb: 0x4008c4b0, context: 0xbe823970
- LSDA: 0x49e94
- callsite: 0x49e9b, action: 0x49ec2, classinfo_table: 0x49ec8, ciEncoding: 144
- ip=0x2c1b3 654508032 32 0
- entering personality function. state: 0; ucb: 0x4008c4b0, context: 0xbe823970
- LSDA: 0x49e40
- callsite: 0x49e45, action: 0x49e86, classinfo_table: 0x49e8c, ciEncoding: 144
- ip=0x2c0ab 1090519040 396 0
Fatal error in EH code: _Unwind_RaiseException failed with reason code: 9
ldc druntime and phobos compiled with -O0 (No optimization) seems to work:
= Throwing new exception of type object.Exception: 0x403be280 (struct at 0x400704ac, classinfo at 0x87170, 1 structs in flight)
- entering personality function. state: 0; ucb: 0x400704b0, context: 0xbeead7e0
- LSDA: 0x6e980
- callsite: 0x6e988, action: 0x6e9a2, classinfo_table: 0x6e9a8, ciEncoding: 144
- ip=0x4125b 72 8 a4
- Found correct landing pad and actionTableStartOffset 1
- ci_size: 4, ci_encoding: 144
- ti_offset: 1
- Comparing catch object.Throwable to exception object.Exception
- Found catch clause for 0x400704ac
- entering personality function. state: 1; ucb: 0x400704b0, context: 0xbeeada3c
- LSDA: 0x6e980
- callsite: 0x6e988, action: 0x6e9a2, classinfo_table: 0x6e9a8, ciEncoding: 144
- ip=0x4125b 72 8 a4
- Found correct landing pad and actionTableStartOffset 1
- ci_size: 4, ci_encoding: 144
- ti_offset: 1
- Comparing catch object.Throwable to exception object.Exception
- Found catch clause for 0x400704ac
- Calling catch block for 0x403be280 (struct at 0x400704ac)
- Setting switch value to: 0x1
- Setting landing pad to: 0x412b0
- Destroyed exception struct at 0x400704ac, 0 structs in flight
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----------------Segmentation fault (core dumped)
When compiling with optimizations turned on the landing pads are not found by the unwind function.
The segmentation fault is reported as a possible stack corruption by gdb (could be alignment issues, see bellow).
One problem I notices is that the ARM ehabi (http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038b/IHI0038B_ehabi.pdf) suggest that _Unwind_Control_Block struct should be aligned to 8 byte boundary. Playing with that didn't do any good.