[PATCH] D13378: [SCEV] Recognize simple br-phi patterns

[Sanjoy Das via llvm-commits]

Diego Novillo via llvm-commits wrote:
> dnovillo added a subscriber: dnovillo.
> dnovillo added a comment.
>
> Sanjoy,
>
> This commit is causing an internal compiler error with the following code:
>
> int x0, x1, x2;
> double *x3;
> int fsolv() {
>
>    int x4, x5 = x4 = 0;
>    for (; x4<  x2; ++x4) {
>      x0 = 0;
>      for (; x0<  x4; ++x0)
>        x1 = x3[x5++];
>    }
>    return 0;
>
> }
>
> Is this something you recognize?  If not, do you mind if I revert your
> commit while you work on the test case?

It is plausible that this is the same issue as in http://reviews.llvm.org/D13460.  If it is possible, can you please try 
D13460 and see if it fixes the ICE?  If not or if trying out a new patch will be too much work, reverting this is okay.

Thanks!
-- Sanjoy


>
> Thanks.  Diego.
>
> $ clang -c -O2 a.c
> clang-3.8:
> /usr/local/google/home/dnovillo/llvm/llvm/lib/Analysis/LazyValueInfo.cpp:632:
> bool (anonymous namespace)::LazyValueInfoCache
> ::solveBlockValueNonLocal((anonymous namespace)::LVILatticeVal&,
> llvm::Value *, llvm::BasicBlock *): Assertion `isa<Argument>(Val)&&
> "Unknown live-in to the entry block"' failed.
> 0  libLLVMSupport.so.3.8       0x00007f484d2fafde
> llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 46
> 1  libLLVMSupport.so.3.8       0x00007f484d2fc119
> 2  libLLVMSupport.so.3.8       0x00007f484d2fab53
> llvm::sys::RunSignalHandlers() + 131
> 3  libLLVMSupport.so.3.8       0x00007f484d2fc35b
> 4  libc.so.6                   0x00007f484a447d40
> 5  libc.so.6                   0x00007f484a447cc9 gsignal + 57
> 6  libc.so.6                   0x00007f484a44b0d8 abort + 328
> 7  libc.so.6                   0x00007f484a440b86
> 8  libc.so.6                   0x00007f484a440c32
> 9  libLLVMAnalysis.so.3.8      0x00007f48504ba546
> 10 libLLVMAnalysis.so.3.8      0x00007f48504b9dd6
> 11 libLLVMAnalysis.so.3.8      0x00007f48504b97b2
> 12 libLLVMAnalysis.so.3.8      0x00007f48504b776e
> 13 libLLVMAnalysis.so.3.8      0x00007f48504b7541
> llvm::LazyValueInfo::getConstantOnEdge(llvm::Value*, llvm::BasicBlock*,
> llvm::BasicBl
> ock*, llvm::Instruction*) + 129
> 14 libLLVMScalarOpts.so.3.8    0x00007f484d60a6ea
> 15 libLLVMScalarOpts.so.3.8    0x00007f484d60a317
> 16 libLLVMCore.so.3.8          0x00007f484f4281ff
> llvm::FPPassManager::runOnFunction(llvm::Function&) + 399
> 17 libLLVMAnalysis.so.3.8      0x00007f48503f1611
> 18 libLLVMAnalysis.so.3.8      0x00007f48503f107d
> 19 libLLVMAnalysis.so.3.8      0x00007f48503f0928
> 20 libLLVMCore.so.3.8          0x00007f484f428caa
> 21 libLLVMCore.so.3.8          0x00007f484f4287d6
> llvm::legacy::PassManagerImpl::run(llvm::Module&) + 342
> 22 libLLVMCore.so.3.8          0x00007f484f4291c1
> llvm::legacy::PassManager::run(llvm::Module&) + 33
> 23 libclangCodeGen.so.3.8      0x00007f484bbb6dd5
> 24 libclangCodeGen.so.3.8      0x00007f484bbb6502
> clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::CodeGenOptions
> const&, clang::TargetOptions const&, clang::LangOptions const&,
> llvm::StringRef, llvm::Module*, clang::BackendAction,
> llvm::raw_pwrite_stream*) + 162
> 25 libclangCodeGen.so.3.8      0x00007f484be89a39
> 26 libclangParse.so.3.8        0x00007f48463905b1
> clang::ParseAST(clang::Sema&, bool, bool) + 817
> 27 libclangFrontend.so.3.8     0x00007f484b402d10
> clang::ASTFrontendAction::ExecuteAction() + 320
> 28 libclangCodeGen.so.3.8      0x00007f484be875f4
> clang::CodeGenAction::ExecuteAction() + 2100
> 29 libclangFrontend.so.3.8     0x00007f484b4027f0
> clang::FrontendAction::Execute() + 112
> 30 libclangFrontend.so.3.8     0x00007f484b39f402
> clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 978
> 31 libclangFrontendTool.so.3.8 0x00007f484affa764
> clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 1172
> 32 clang-3.8                   0x0000000000423f08
> cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 920
> 33 clang-3.8                   0x0000000000417839
> 34 clang-3.8                   0x0000000000416715 main + 2277
> 35 libc.so.6                   0x00007f484a432ec5 __libc_start_main + 245
> 36 clang-3.8                   0x0000000000415ce4
> Stack dump:
>
> 1.<eof>  parser at end of file
> 2. Per-module optimization passes
> 3. Running pass 'CallGraph Pass Manager' on module 'a.c'.
> 4. Running pass 'Value Propagation' on function '@fsolv'
>
>
> Repository:
>    rL LLVM
>
> http://reviews.llvm.org/D13378
>
>
>
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