[LLVMbugs] [Bug 3168] New: Assertion failure when using ocaml GC

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=3168

           Summary: Assertion failure when using ocaml GC
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Common Code Generator Code
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: wesleypeck at gmail.com
                CC: llvmbugs at cs.uiuc.edu


The LLVM code shown below causes an assertion failure:
declare ccc void @oread_runtime_casenotcovered()
declare void @llvm.gcroot(i8**,i8*)
define i32* @append() gc "ocaml"
{
entry:
        switch i32 0, label %L2 [i32 0, label %L1]
L1:
        %var8 = alloca i8*
        call void @llvm.gcroot(i8** %var8,i8* null)
        br label %L3
L2:
        call ccc void @oread_runtime_casenotcovered()
        unreachable
L3:
        ret i32* null
}

Playing around with the code a bit, I have found that the assertion can be
eliminated by doing any of the following:
    1) Using the shadow-stack GC instead of the ocaml GC
    2) Using opt between llvm-as and llc
    3) Moving the alloca instruction to right below the entry label

The assertion produced is the following:
Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"),
function cast, file
/Users/peckw/Projects/llvm/llvm/include/llvm/Support/Casting.h, line 199.
0   llc                                 0x00953d9c
_ZNSt8_Rb_treeIN4llvm3sys4PathES2_St9_IdentityIS2_ESt4lessIS2_ESaIS2_EE13insert_uniqueERKS2_
+ 7948
1   libSystem.B.dylib                   0x926da09b _sigtramp + 43
2   ???                                 0xffffffff 0x0 + 4294967295
3   libSystem.B.dylib                   0x92752ec2 raise + 26
4   libSystem.B.dylib                   0x9276247f abort + 73
5   libSystem.B.dylib                   0x92754063 __assert_rtn + 101
6   llc                                 0x005f2c36
_ZN4llvm15CvtRndSatSDNodeD1Ev + 90918
7   llc                                 0x005f30f6
_ZN4llvm15CvtRndSatSDNodeD1Ev + 92134
8   llc                                 0x00620263
_ZN4llvm15CvtRndSatSDNodeD1Ev + 276819
9   llc                                 0x0062e0ac
_ZN4llvm4castINS_18DbgRegionStartInstENS_8CallInstEEENS_10cast_rettyIT_T0_E8ret_typeERKS5_
+ 29212
10  llc                                 0x0062f3a4
_ZN4llvm4castINS_18DbgRegionStartInstENS_8CallInstEEENS_10cast_rettyIT_T0_E8ret_typeERKS5_
+ 34068
11  llc                                 0x00630f43
_ZN4llvm4castINS_18DbgRegionStartInstENS_8CallInstEEENS_10cast_rettyIT_T0_E8ret_typeERKS5_
+ 41139
12  llc                                 0x008cf49f _ZN4llvm12FunctionPassD1Ev +
33983
13  llc                                 0x008cfa38 _ZN4llvm12FunctionPassD1Ev +
35416
14  llc                                 0x008cfbe6 _ZN4llvm12FunctionPassD1Ev +
35846
15  llc                                 0x000030a7 _mh_execute_header + 8359
16  llc                                 0x00001d36 _mh_execute_header + 3382


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