[llvm-mca] Clear the content of map VariantDescriptors in InstrBuilder before we start analyzing a new CodeBlock. NFCI.

Different CodeBlocks don't overlap. The same MCInst cannot appear in more than
one code block because all blocks are instantiated before the simulation is run.

We should always clear the content of map VariantDescriptors before every
simulation, since VariantDescriptors cannot possibly store useful information
for the next blocks. It is also "safer" to clear its content because `MCInst*`
is used as the key type for map VariantDescriptors.

llvm-svn: 336142

2 files changed, 5 insertions, 0 deletions

diff --git a/llvm/tools/llvm-mca/InstrBuilder.h b/llvm/tools/llvm-mca/InstrBuilder.h
index 1c325d911e3..e5e80d7cf79 100644
--- a/llvm/tools/llvm-mca/InstrBuilder.h
+++ b/llvm/tools/llvm-mca/InstrBuilder.h
@@ -69,6 +69,8 @@ public:
     return ProcResourceMasks;
   }
 
+  void clear() { VariantDescriptors.shrink_and_clear(); }
+
   std::unique_ptr<Instruction> createInstruction(const llvm::MCInst &MCI);
 };
 } // namespace mca
diff --git a/llvm/tools/llvm-mca/llvm-mca.cpp b/llvm/tools/llvm-mca/llvm-mca.cpp
index 4cdd6baba5e..6bea82741db 100644
--- a/llvm/tools/llvm-mca/llvm-mca.cpp
+++ b/llvm/tools/llvm-mca/llvm-mca.cpp
@@ -547,6 +547,9 @@ int main(int argc, char **argv) {
 
     P->run();
     Printer.printReport(TOF->os());
+
+    // Clear the InstrBuilder internal state in preparation for another round.
+    IB.clear();
   }
 
   TOF->keep();