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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Changed WTFCrash to not trash the crash site register state."
href="https://bugs.webkit.org/show_bug.cgi?id=153996">153996</a>
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<th>Summary</th>
<td>Changed WTFCrash to not trash the crash site register state.
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<th>Classification</th>
<td>Unclassified
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<th>Product</th>
<td>WebKit
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<th>Version</th>
<td>WebKit Local Build
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<th>Hardware</th>
<td>Unspecified
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<th>OS</th>
<td>Unspecified
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>Normal
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<th>Priority</th>
<td>P2
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<th>Component</th>
<td>JavaScriptCore
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>mark.lam@apple.com
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<pre>When doing post-mortem crash site analysis using data from crash reports, it is immensely valuable to be able to infer the crashing program's state from the register values at crash time. However, for RELEASE_ASSERT failures, we crash using WTFCrash(), and WTFCrash() is currently implemented as a function call that, in turn, calls a lot of other functions to do crash handling before actually crashing. As a result, the register values captured in the crash reports are not likely to still contain the values used by the caller function that failed the RELEASE_ASSERT.
This patch aims to remedy this issue for non-debug builds on OS(DARWIN) ports. It does so by changing WTFCrash() into an inlined function that has an inlined asm statement to issues the CPU specific breakpoint trap instruction. As a result, for non-debug OS(DARWIN) builds, crashes due to failed RELEASE_ASSERTs will now show up in crash reports as crashing due to EXC_BREAKPOINT (SIGTRAP) instead of a EXC_BAD_ACCESS (SIGSEGV) on address 0xbbadbeef.
For debug and non-DARWIN builds, WTFCrash() behavior currently remains unchanged.</pre>
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