llvmbot
commented
3 months ago @llvm/issue-subscribers-backend-amdgpu
Author: Joseph Huber (jhuber6)
The following code is a reduced case from the libc++ lexicographical comparison test, https://godbolt.org/z/MnjWbK3ca. This fails when the GVN pass attempts to compare the two values from the GEP. I reduced it further, but wasn't sure if it was the same issue so I figured I'd show both https://godbolt.org/z/hE6d6P6s3, this one is shorter.
```llvm
define void @iterator(ptr addrspace(5) %0, i64 %1, i32 %2) {
%4 = addrspacecast ptr addrspace(5) %0 to ptr
%5 = getelementptr i8, ptr addrspace(5) %0, i32 16
%6 = getelementptr i8, ptr %4, i64 %1
%7 = getelementptr i8, ptr addrspace(5) %5, i32 %2
%8 = load i32, ptr %6, align 4
%9 = load i32, ptr addrspace(5) %7, align 4
%10 = icmp slt i32 %8, %9
ret void
}
```
```console
$ opt -passes=gvn -mtriple=amdgcn-amd-amdhsa bug.llopt: /root/llvm-project/llvm/lib/Analysis/ValueTracking.cpp:313: bool llvm::isKnownNonEqual(const llvm::Value*, const llvm::Value*, const llvm::DataLayout&, llvm::AssumptionCache*, const llvm::Instruction*, const llvm::DominatorTree*, bool): Assertion `V1->getType() == V2->getType() && "Testing equality of non-equal types!"' failed.
#0 0x0000000004f49178 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4f49178)
#1 0x0000000004f468ec SignalHandler(int) Signals.cpp:0:0
#2 0x000073c6b4c42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#3 0x000073c6b4c969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#4 0x000073c6b4c42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#5 0x000073c6b4c287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#6 0x000073c6b4c2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#7 0x000073c6b4c39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#8 0x00000000046e330c (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x46e330c)
#9 0x00000000043828c3 llvm::BasicAAResult::aliasGEP(llvm::GEPOperator const*, llvm::LocationSize, llvm::Value const*, llvm::LocationSize, llvm::Value const*, llvm::Value const*, llvm::AAQueryInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x43828c3)
#10 0x0000000004382cd1 llvm::BasicAAResult::aliasCheckRecursive(llvm::Value const*, llvm::LocationSize, llvm::Value const*, llvm::LocationSize, llvm::AAQueryInfo&, llvm::Value const*, llvm::Value const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4382cd1)
#11 0x0000000004385337 llvm::BasicAAResult::aliasCheck(llvm::Value const*, llvm::LocationSize, llvm::Value const*, llvm::LocationSize, llvm::AAQueryInfo&, llvm::Instruction const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4385337)
#12 0x0000000004385917 llvm::BasicAAResult::alias(llvm::MemoryLocation const&, llvm::MemoryLocation const&, llvm::AAQueryInfo&, llvm::Instruction const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4385917)
```
arsenm
The following code is a reduced case from the libc++ lexicographical comparison test, https://godbolt.org/z/MnjWbK3ca. This fails when the GVN pass attempts to compare the two values from the GEP. I reduced it further, but wasn't sure if it was the same issue so I figured I'd show both https://godbolt.org/z/hE6d6P6s3, this one is shorter.