[PATCH] D86210: [llvm-reduce] Skip terminators when reducing instructions.
Florian Hahn via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 19 06:06:50 PDT 2020
fhahn created this revision.
fhahn added reviewers: lebedev.ri, dblaikie.
Herald added a project: LLVM.
fhahn requested review of this revision.
Removing terminators will result in invalid IR, making further
reductions pointless. I do not think there is any valid use case where
we actually want to create invalid IR as part of a reduction.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D86210
Files:
llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
Index: llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
===================================================================
--- llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
+++ llvm/tools/llvm-reduce/deltas/ReduceInstructions.cpp
@@ -24,10 +24,14 @@
std::set<Instruction *> InstToKeep;
for (auto &F : *Program)
- for (auto &BB : F)
- for (auto &Inst : BB)
+ for (auto &BB : F) {
+ // Removing the terminator would make the block invalid. Only iterate over
+ // instructions before the terminator.
+ InstToKeep.insert(BB.getTerminator());
+ for (auto &Inst : make_range(BB.begin(), std::prev(BB.end())))
if (O.shouldKeep())
InstToKeep.insert(&Inst);
+ }
std::vector<Instruction *> InstToDelete;
for (auto &F : *Program)
@@ -49,7 +53,8 @@
int InstCount = 0;
for (auto &F : *Program)
for (auto &BB : F)
- InstCount += BB.getInstList().size();
+ // Well-formed blocks have terminators, which we cannot remove.
+ InstCount += BB.getInstList().size() - 1;
outs() << "Number of instructions: " << InstCount << "\n";
return InstCount;
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