[AMDGPU] Fix running ResourceUsageAnalysis

[sebastian-ne]

Summary

Clear the map when running the analysis multiple times.
The assertion below that should ensure that every function is only
analyzed once triggered sometimes (once every ~70 compiles of some
graphics pipelines).

If someone knows how to add a testcase, that would be nice, because
I don't know how to test for this.

[arsenm]

I don't think there's a way to test this short of a unit test running a custom pass pipeline

[madhur13490]

If you want to you can emit some debugging message after clearing the map and have a llc lit test with the debug flag to CHECK the debugging message.

[sebastian-ne]

The previous fix here was actually wrong (and failed lit tests), resetting the map should be done in doInitialization.

llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.h

struct SIFunctionResourceInfo {
     int32_t getTotalNumSGPRs(const GCNSubtarget &ST) const;
     int32_t getTotalNumVGPRs(const GCNSubtarget &ST) const;
   };
 
   AMDGPUResourceUsageAnalysis() : CallGraphSCCPass(ID) {}
 
   bool runOnSCC(CallGraphSCC &SCC) override;
 
+  bool doInitialization(CallGraph &CG) override {
+    CallGraphResourceInfo.clear();
+    return CallGraphSCCPass::doInitialization(CG);
+  }
+
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<MachineModuleInfoWrapperPass>();
     AU.setPreservesAll();
   }
 
   const SIFunctionResourceInfo &getResourceInfo(const Function *F) const {
-    return CallGraphResourceInfo.find(F)->getSecond();
+    auto Info = CallGraphResourceInfo.find(F);
+    assert(Info != CallGraphResourceInfo.end() &&
+           "Failed to find resource info for function");
+    return Info->getSecond();
   }
 
 private:
   SIFunctionResourceInfo analyzeResourceUsage(const MachineFunction &MF,
                                               const TargetMachine &TM) const;
   void propagateIndirectCallRegisterUsage();
 
   DenseMap<const Function *, SIFunctionResourceInfo> CallGraphResourceInfo;
 };
 } // namespace llvm
 #endif // LLVM_LIB_TARGET_AMDGPU_AMDGPURESOURCEUSAGEANALYSIS_H