http://llvm.org/bugs/show_bug.cgi?id=13731
Bug #: 13731
Summary: RecursiveASTVisitor crashes on very long if/else
chains (1000~2000 cases)
Product: clang
Version: trunk
Platform: Macintosh
OS/Version: All
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 9136
--> http://llvm.org/bugs/attachment.cgi?id=9136
2000 if statements in a chain
My friend sent me a block of code the analyzer crashed on; we eventually
reduced it down to a single chain of maybe 1000 if/else cases -- a
presumably-autogenerated poor implementation of option parsing. On statement
trees this deep, RecursiveASTVisitor crashes; both 'clang --analyze' and 'clang
-Wimplicit-fallthrough' will crash on the attached test case...in release
builds only.
Curious, I tested more carefully. Under -O0 and -O1 RecursiveASTVisitor does
manage to visit all the statements (presumably). Under -O2 and -O3 the crash
occurs -- it's a stack overflow.
I know for BinaryOperators we switch to an iterative data path if requested. I
realize that this is pretty unlikely code, but we shouldn't /crash/ trying to
traverse it. I'm not sure why it is only optimized builds that crash, and that
worries me.
This is a recent build of trunk clang compiled using a recent Apple clang. I
did not try compiling with GCC, bootstrapping, or digging up an older Apple
clang.
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