[llvm] a678c67 - IR: Fix const-correctness of SwitchInst::CaseIterator and CaseHandle

[Duncan P. N. Exon Smith via llvm-commits]

Author: Duncan P. N. Exon Smith
Date: 2021-11-12T14:07:04-08:00
New Revision: a678c6743f536dac67b3714fd8c71dca7b1ae082

URL: https://github.com/llvm/llvm-project/commit/a678c6743f536dac67b3714fd8c71dca7b1ae082
DIFF: https://github.com/llvm/llvm-project/commit/a678c6743f536dac67b3714fd8c71dca7b1ae082.diff

LOG: IR: Fix const-correctness of SwitchInst::CaseIterator and CaseHandle

Fix some confusion between the two types of `const` a pointer/iterator
can have. Users of a SwitchInst::CaseIterator should not (and do not!)
manually mutate the SwitchInst::CaseHandle that tracks its internal
state. Change operator*() to return `const CaseHandle&`, remove the
non-const-qualified operator*(), and const-qualify
CaseHandle::setValue() and CaseHandle::setSuccessor().

Differential Revision: https://reviews.llvm.org/D113788

Added: 
    

Modified: 
    llvm/include/llvm/IR/Instructions.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 45984d2d0a72..6d32a898b668 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -3350,14 +3350,14 @@ class SwitchInst : public Instruction {
     CaseHandle(SwitchInst *SI, ptr
diff _t Index) : CaseHandleImpl(SI, Index) {}
 
     /// Sets the new value for current case.
-    void setValue(ConstantInt *V) {
+    void setValue(ConstantInt *V) const {
       assert((unsigned)Index < SI->getNumCases() &&
              "Index out the number of cases.");
       SI->setOperand(2 + Index*2, reinterpret_cast<Value*>(V));
     }
 
     /// Sets the new successor for current case.
-    void setSuccessor(BasicBlock *S) {
+    void setSuccessor(BasicBlock *S) const {
       SI->setSuccessor(getSuccessorIndex(), S);
     }
   };
@@ -3366,7 +3366,7 @@ class SwitchInst : public Instruction {
   class CaseIteratorImpl
       : public iterator_facade_base<CaseIteratorImpl<CaseHandleT>,
                                     std::random_access_iterator_tag,
-                                    CaseHandleT> {
+                                    const CaseHandleT> {
     using SwitchInstT = typename CaseHandleT::SwitchInstType;
 
     CaseHandleT Case;
@@ -3425,7 +3425,6 @@ class SwitchInst : public Instruction {
       assert(Case.SI == RHS.Case.SI && "Incompatible operators.");
       return Case.Index < RHS.Case.Index;
     }
-    CaseHandleT &operator*() { return Case; }
     const CaseHandleT &operator*() const { return Case; }
   };
 
@@ -3520,7 +3519,7 @@ class SwitchInst : public Instruction {
         const_cast<const SwitchInst *>(this)->findCaseValue(C)->getCaseIndex());
   }
   ConstCaseIt findCaseValue(const ConstantInt *C) const {
-    ConstCaseIt I = llvm::find_if(cases(), [C](ConstCaseHandle &Case) {
+    ConstCaseIt I = llvm::find_if(cases(), [C](const ConstCaseHandle &Case) {
       return Case.getCaseValue() == C;
     });
     if (I != case_end())