[LowerSwitch] Implement verifyAnalysis

[jayfoad]

This pass is used like an analysis so it's useful to be able to verify
passes that claim to have preserved it.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

@llvm/pr-subscribers-llvm-transforms

Changes

This pass is used like an analysis so it's useful to be able to verify
passes that claim to have preserved it.

---

Full diff: https://github.com/llvm/llvm-project/pull/68294.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Utils/LowerSwitch.cpp (+10)

diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index 227de425ff85549..2b046017d06abda 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -569,8 +569,17 @@ class LowerSwitchLegacyPass : public FunctionPass {
     initializeLowerSwitchLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
+  // Remember the current function. Only used for verification.
+  Function *F;
+
   bool runOnFunction(Function &F) override;
 
+  void verifyAnalysis() const override {
+    for (auto &BB : *F)
+      assert(!isa<SwitchInst>(BB.getTerminator()) &&
+             "Found an unlowered switch!");
+  }
+
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<LazyValueInfoWrapperPass>();
   }
@@ -596,6 +605,7 @@ FunctionPass *llvm::createLowerSwitchPass() {
 }
 
 bool LowerSwitchLegacyPass::runOnFunction(Function &F) {
+  this->F = &F;
   LazyValueInfo *LVI = &getAnalysis<LazyValueInfoWrapperPass>().getLVI();
   auto *ACT = getAnalysisIfAvailable<AssumptionCacheTracker>();
   AssumptionCache *AC = ACT ? &ACT->getAssumptionCache(F) : nullptr;

[arsenm]

Is verifyAnalysis supposed to work in a release build? I think you're in danger of the unused member variable as is

[jayfoad]

I'm just trying to follow existing patterns. They all seem to use assert so won't do anything in a normal Release build. I don't think most compilers warn about unused public fields do they?

[ruiling]

I think #68662 can help on this?

[jayfoad]

I think #68662 can help on this?

If we go with #68662 then LowerSwitch is no longer used like an analysis, so there would be no need to verify that it is preserved.

[jayfoad]

I think #68662 can help on this?

If we go with #68662 then LowerSwitch is no longer used like an analysis, so there would be no need to verify that it is preserved.

We went with #68662.