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[CIR] Add the ability to detect if SwitchOp covers all the cases #171246

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Merged
badumbatish merged 2 commits into from
Dec 11, 2025
Merged

[CIR] Add the ability to detect if SwitchOp covers all the cases #171246

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40d3ddb
Add switch case covered cirops.td
badumbatish Dec 8, 2025
368fbbc
Resolve PR comments
badumbatish Dec 10, 2025
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8 changes: 7 additions & 1 deletion clang/include/clang/CIR/Dialect/IR/CIROps.td
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Original file line number Diff line number Diff line change
Expand Up @@ -1047,6 +1047,11 @@ def CIR_SwitchOp : CIR_Op<"switch", [
conditionally executing multiple regions of code. The operand to an switch
is an integral condition value.

Besides accepting an int type of condition and regions of cir code, it also accepts
a boolean allEnumCasesCovered indicating if all cases of an enum is covered. Note that
having a default CaseOp inside the switch doesn't imply allEnumCasesCovered, the OG AST switch
needs to have each case spelled out.

The set of `cir.case` operations and their enclosing `cir.switch`
represent the semantics of a C/C++ switch statement. Users can use
`collectCases(llvm::SmallVector<CaseOp> &cases)` to collect the `cir.case`
Expand Down Expand Up @@ -1173,7 +1178,8 @@ def CIR_SwitchOp : CIR_Op<"switch", [
```
}];

let arguments = (ins CIR_IntType:$condition);
let arguments = (ins CIR_IntType:$condition,
DefaultValuedAttr<BoolAttr, "false">:$allEnumCasesCovered);

let regions = (region AnyRegion:$body);

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2 changes: 2 additions & 0 deletions clang/lib/CIR/CodeGen/CIRGenStmt.cpp
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Expand Up @@ -1105,6 +1105,8 @@ mlir::LogicalResult CIRGenFunction::emitSwitchStmt(const clang::SwitchStmt &s) {
terminateBody(builder, caseOp.getCaseRegion(), caseOp.getLoc());
terminateBody(builder, swop.getBody(), swop.getLoc());

swop.setAllEnumCasesCovered(s.isAllEnumCasesCovered());

return res;
}

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30 changes: 30 additions & 0 deletions clang/test/CIR/IR/switch.cir
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Expand Up @@ -36,3 +36,33 @@ cir.func @s0() {
// CHECK-NEXT: }
// CHECK-NEXT: cir.yield
// CHECK-NEXT: }


// Pretends that this is lowered from a C file and was tagged with allEnumCasesCovered = true
cir.func @s1(%1 : !s32i) {
cir.switch (%1 : !s32i) {
cir.case (default, []) {
cir.return
}
cir.case (equal, [#cir.int<1> : !s32i]) {
cir.yield
}
cir.case (equal, [#cir.int<2> : !s32i]) {
cir.yield
}
cir.yield
} { allEnumCasesCovered = true}
cir.return
}
// CHECK: cir.switch (%arg0 : !s32i) {
// CHECK-NEXT: cir.case(default, []) {
// CHECK-NEXT: cir.return
// CHECK-NEXT: }
// CHECK-NEXT: cir.case(equal, [#cir.int<1> : !s32i]) {
// CHECK-NEXT: cir.yield
// CHECK-NEXT: }
// CHECK-NEXT: cir.case(equal, [#cir.int<2> : !s32i]) {
// CHECK-NEXT: cir.yield
// CHECK-NEXT: }
// CHECK-NEXT: cir.yield
// CHECK-NEXT: } {allEnumCasesCovered = true}