forked from OSchip/llvm-project
c63b492bcd
Summary:
This patch is crucial for proving equality laundered/stripped
pointers. eg:
bool foo(A *a) {
return a == std::launder(a);
}
Clang with -fstrict-vtable-pointers will emit something like:
define dso_local zeroext i1 @_Z3fooP1A(%struct.A* %a) {
entry:
%c = bitcast %struct.A* %a to i8*
%call = tail call i8* @llvm.launder.invariant.group.p0i8(i8* %c)
%0 = bitcast %struct.A* %a to i8*
%1 = tail call i8* @llvm.strip.invariant.group.p0i8(i8* %0)
%2 = tail call i8* @llvm.strip.invariant.group.p0i8(i8* %call)
%cmp = icmp eq i8* %1, %2
ret i1 %cmp
}
and because %2 can be replaced with @llvm.strip.invariant.group(%0)
and that %2 and %1 will produce the same value (because strip is readnone)
we can replace compare with true.
Reviewers: rsmith, hfinkel, majnemer, amharc, kuhar
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D47423
llvm-svn: 336963
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| .. | ||
| Analysis | ||
| AsmParser | ||
| BinaryFormat | ||
| Bitcode | ||
| CodeGen | ||
| DebugInfo | ||
| Demangle | ||
| ExecutionEngine | ||
| FuzzMutate | ||
| Fuzzer | ||
| IR | ||
| IRReader | ||
| LTO | ||
| LineEditor | ||
| Linker | ||
| MC | ||
| Object | ||
| ObjectYAML | ||
| Option | ||
| Passes | ||
| ProfileData | ||
| Support | ||
| TableGen | ||
| Target | ||
| Testing | ||
| ToolDrivers | ||
| Transforms | ||
| WindowsManifest | ||
| XRay | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||