================
@@ -6519,17 +6518,60 @@ static bool SwitchToLookupTable(SwitchInst *SI,
IRBuilder<> &Builder,
SmallDenseMap<PHINode *, Type *> ResultTypes;
SmallVector<PHINode *, 4> PHIs;
- for (SwitchInst::CaseIt E = SI->case_end(); CI != E; ++CI) {
- ConstantInt *CaseVal = CI->getCaseValue();
- if (CaseVal->getValue().slt(MinCaseVal->getValue()))
- MinCaseVal = CaseVal;
- if (CaseVal->getValue().sgt(MaxCaseVal->getValue()))
- MaxCaseVal = CaseVal;
+ SmallVector<ConstantInt *, 8> CaseVals;
+ for (auto CI : SI->cases()) {
+ ConstantInt *CaseVal = CI.getCaseValue();
+ CaseVals.push_back(CaseVal);
+ }
+
+ // We want to find a range of indexes that will create the minimal table.
+ // We can treat all possible index values as a circle. For example, the i8 is
+ // [-128, -1] and [0, 127]. After that find the minimal range from this
circle
----------------
DianQK wrote:
The new comment is below:
We consider cases where the starting to the endpoint will cross the signed max
and min. For example, for the i8 range `[-128, -127, 126, 127]`, we choose from
126 to -127. The length of the lookup table is 4.
https://github.com/llvm/llvm-project/pull/67885
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