forked from OSchip/llvm-project
96e6ce4cd3
Summary:
In D65186 and related patches, MustBeExecutedContextExplorer is introduced. This enables us to traverse instructions guaranteed to execute from function entry. If we can know the argument is used as `dereferenceable` or `nonnull` in these instructions, we can mark `dereferenceable` or `nonnull` in the argument definition:
1. Memory instruction (similar to D64258)
Trace memory instruction pointer operand. Currently, only inbounds GEPs are traced.
```
define i64* @f(i64* %a) {
entry:
%add.ptr = getelementptr inbounds i64, i64* %a, i64 1
; (because of inbounds GEP we can know that %a is at least dereferenceable(16))
store i64 1, i64* %add.ptr, align 8
ret i64* %add.ptr ; dereferenceable 8 (because above instruction stores into it)
}
```
2. Propagation from callsite (similar to D27855)
If `deref` or `nonnull` are known in call site parameter attributes we can also say that argument also that attribute.
```
declare void @use3(i8* %x, i8* %y, i8* %z);
declare void @use3nonnull(i8* nonnull %x, i8* nonnull %y, i8* nonnull %z);
define void @parent1(i8* %a, i8* %b, i8* %c) {
call void @use3nonnull(i8* %b, i8* %c, i8* %a)
; Above instruction is always executed so we can say that@parent1(i8* nonnnull %a, i8* nonnull %b, i8* nonnull %c)
call void @use3(i8* %c, i8* %a, i8* %b)
ret void
}
```
Reviewers: jdoerfert, sstefan1, spatel, reames
Reviewed By: jdoerfert
Subscribers: xbolva00, hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65402
llvm-svn: 374063
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| .. | ||
| AlwaysInliner.cpp | ||
| ArgumentPromotion.cpp | ||
| Attributor.cpp | ||
| BarrierNoopPass.cpp | ||
| BlockExtractor.cpp | ||
| CMakeLists.txt | ||
| CalledValuePropagation.cpp | ||
| ConstantMerge.cpp | ||
| CrossDSOCFI.cpp | ||
| DeadArgumentElimination.cpp | ||
| ElimAvailExtern.cpp | ||
| ExtractGV.cpp | ||
| ForceFunctionAttrs.cpp | ||
| FunctionAttrs.cpp | ||
| FunctionImport.cpp | ||
| GlobalDCE.cpp | ||
| GlobalOpt.cpp | ||
| GlobalSplit.cpp | ||
| HotColdSplitting.cpp | ||
| IPConstantPropagation.cpp | ||
| IPO.cpp | ||
| InferFunctionAttrs.cpp | ||
| InlineSimple.cpp | ||
| Inliner.cpp | ||
| Internalize.cpp | ||
| LLVMBuild.txt | ||
| LoopExtractor.cpp | ||
| LowerTypeTests.cpp | ||
| MergeFunctions.cpp | ||
| PartialInlining.cpp | ||
| PassManagerBuilder.cpp | ||
| PruneEH.cpp | ||
| SCCP.cpp | ||
| SampleProfile.cpp | ||
| StripDeadPrototypes.cpp | ||
| StripSymbols.cpp | ||
| SyntheticCountsPropagation.cpp | ||
| ThinLTOBitcodeWriter.cpp | ||
| WholeProgramDevirt.cpp | ||