http://llvm.org/bugs/show_bug.cgi?id=14578
Bug #: 14578
Summary: Apparent miscompilation with opt -inline
-sroa/-scalarrepl and llc -O1
Product: new-bugs
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 9679
--> http://llvm.org/bugs/attachment.cgi?id=9679
Testcase
The attached bitcode seems to be getting miscompiled after opt -inline -sroa
and llc -O1, on an x86-64 host. Doing opt -inline and opt -sroa separately
hides the issue.
Since both opt -inline -sroa and llc -O1 are required, I unfortunately have no
idea at what level the bug is. (Aside from the usual miscompilation caveats:
the original code itself could be at fault, or even the backend of Clang.)
I'm sorry about the large bitcode, but reducing this is a royal pain. bugpoint
doesn't help, it just moves the two global constants to a separate bitcode
file. (Or, without -disable-loop-extraction, crashes --- see Bug 14370.)
Results of various kinds of optimizations with LLVM trunk (r169915):
$ llc -O1 < misbehaviour.bc | gcc -x assembler - && ./a.out
OK
$ opt -inline -sroa < misbehaviour.bc | llc -O0 | gcc -x assembler - && ./a.out
OK
$ opt -inline -sroa < misbehaviour.bc | llc -O1 | gcc -x assembler - && ./a.out
zsh: segmentation fault (core dumped) ./a.out
$ opt -inline < misbehaviour.bc | opt -sroa | llc -O1 | gcc -x assembler - &&
./a.out
OK
$ opt -O3 < misbehaviour.bc | llc -O0 | gcc -x assembler - && ./a.out
OK
$ opt -O3 < misbehaviour.bc | llc -O1 | gcc -x assembler - && ./a.out
zsh: segmentation fault (core dumped) ./a.out
Using -scalarrepl in place of -sroa affects none of these.
The error pointed out by valgrind in the segfaulting cases is "Invalid read of
size 8" on address 0x18.
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