| Message ID | 4D70CBA7.8030407@codesourcery.com |
|---|---|
| State | New |
| Headers | show |
On Fri, 2011-03-04 at 11:23 +0000, Andrew Stubbs wrote: > The attached patch, submitted on behalf of Dan Jacobowitz, fixes an > unwind bug when using RealView and libgcc. > > It's an old patch that has been in CodeSourcery and Linaro toolchains > for sometime, but somehow escaped being posted here. I would like to see some context around this patch before accepting or rejecting this, maybe a testcase (agreed that this is harder) or a description of the problem this patch is attempting to fix. cheers Ramana --
On 09/03/11 16:12, Ramana Radhakrishnan wrote: > On Fri, 2011-03-04 at 11:23 +0000, Andrew Stubbs wrote: >> The attached patch, submitted on behalf of Dan Jacobowitz, fixes an >> unwind bug when using RealView and libgcc. >> >> It's an old patch that has been in CodeSourcery and Linaro toolchains >> for sometime, but somehow escaped being posted here. > > I would like to see some context around this patch before accepting or > rejecting this, maybe a testcase (agreed that this is harder) or a > description of the problem this patch is attempting to fix. A testcase would be difficult. GCC won't produce anything that will exercise this code. We'd have to cook something up in hand-coded assembler, or maybe import something from RVCT - I don't know. However, the logic can easily be compared with the ARM EHABI document, section 9.2: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf The key sentences are: "If the high bit is set in the word containing N, then the type_info list is followed by a prel31 landing pad offset (with bit 31 clear) to be entered in the event that no type matches the thrown type. High bit clear in the N word signifies that implicitly the no match case should result in a call to __cxa_call_unexpected. When the high bit clear format is used, object producers must emit an R_ARM_NONE relocation to __cxa_call_unexpected to indicate the dependency to the linker." (Thanks to Paul Brook for explaining this to me. :) Andrew
On 11/03/11 17:21, Andrew Stubbs wrote: > On 09/03/11 16:12, Ramana Radhakrishnan wrote: >> On Fri, 2011-03-04 at 11:23 +0000, Andrew Stubbs wrote: >>> The attached patch, submitted on behalf of Dan Jacobowitz, fixes an >>> unwind bug when using RealView and libgcc. >>> >>> It's an old patch that has been in CodeSourcery and Linaro toolchains >>> for sometime, but somehow escaped being posted here. >> >> I would like to see some context around this patch before accepting or >> rejecting this, maybe a testcase (agreed that this is harder) or a >> description of the problem this patch is attempting to fix. > > A testcase would be difficult. GCC won't produce anything that will > exercise this code. We'd have to cook something up in hand-coded > assembler, or maybe import something from RVCT - I don't know. > > However, the logic can easily be compared with the ARM EHABI document, > section 9.2: > > http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf > > > The key sentences are: > > "If the high bit is set in the word containing N, then the type_info > list is followed by a prel31 landing pad offset (with bit 31 clear) > to be entered in the event that no type matches the thrown type. High > bit clear in the N word signifies that implicitly the no match case > should result in a call to __cxa_call_unexpected. When the high bit > clear format is used, object producers must emit an R_ARM_NONE > relocation to __cxa_call_unexpected to indicate the dependency to the > linker." This is OK for trunk. cheers Ramana
On 14/03/11 21:21, Ramana Radhakrishnan wrote:
> This is OK for trunk.
Committed, thanks.
Andrew
2008-09-08 Daniel Jacobowitz <dan@codesourcery.com> gcc/ * config/arm/unwind-arm.c (__gnu_unwind_pr_common): Correct test for barrier handlers. --- a/gcc/config/arm/unwind-arm.c +++ b/gcc/config/arm/unwind-arm.c @@ -1196,8 +1196,6 @@ __gnu_unwind_pr_common (_Unwind_State state, ucbp->barrier_cache.bitpattern[4] = (_uw) &data[1]; if (data[0] & uint32_highbit) - phase2_call_unexpected_after_unwind = 1; - else { data += rtti_count + 1; /* Setup for entry to the handler. */ @@ -1207,6 +1205,8 @@ __gnu_unwind_pr_common (_Unwind_State state, _Unwind_SetGR (context, 0, (_uw) ucbp); return _URC_INSTALL_CONTEXT; } + else + phase2_call_unexpected_after_unwind = 1; } if (data[0] & uint32_highbit) data++;