remove splitSwitchCases step

Signed-off-by: Nathan Gauër <[email protected]>

Author: Keenuts

llvm/lib/Target/SPIRV/SPIRVStructurizer.cpp

@@ -1158,42 +1158,6 @@ class SPIRVStructurizer : public FunctionPass {
     return Modified;
   }
 
-  // Makes sure every case target in |F| is unique. If 2 cases branch to the
-  // same basic block, one of the targets is updated so it jumps to a new basic
-  // block ending with a single unconditional branch to the original target.
-  bool splitSwitchCases(Function &F) {
-    bool Modified = false;
-
-    for (BasicBlock &BB : F) {
-      SwitchInst *SI = dyn_cast<SwitchInst>(BB.getTerminator());
-      if (!SI)
-        continue;
-
-      BlockSet Seen;
-      Seen.insert(SI->getDefaultDest());
-
-      auto It = SI->case_begin();
-      while (It != SI->case_end()) {
-        BasicBlock *Target = It->getCaseSuccessor();
-        if (Seen.count(Target) == 0) {
-          Seen.insert(Target);
-          ++It;
-          continue;
-        }
-
-        Modified = true;
-        BasicBlock *NewTarget =
-            BasicBlock::Create(F.getContext(), "new.sw.case", &F);
-        IRBuilder<> Builder(NewTarget);
-        Builder.CreateBr(Target);
-        SI->addCase(It->getCaseValue(), NewTarget);
-        It = SI->removeCase(It);
-      }
-    }
-
-    return Modified;
-  }
-
   bool IsRequiredForPhiNode(BasicBlock *BB) {
     for (BasicBlock *Successor : successors(BB)) {
       for (PHINode &Phi : Successor->phis()) {
@@ -1321,11 +1285,6 @@ class SPIRVStructurizer : public FunctionPass {
   virtual bool runOnFunction(Function &F) override {
     bool Modified = false;
 
-    // In LLVM, Switches are allowed to have several cases branching to the same
-    // basic block. In SPIR-V, each target must be a distrinct block. This
-    // function makes sure each target is unique.
-    Modified |= splitSwitchCases(F);
-
     // LLVM allows conditional branches to have both side jumping to the same
     // block. It also allows switched to have a single default, or just one
     // case. Cleaning this up now.