================
@@ -33,6 +33,141 @@ struct HoistAllocasPass : public
impl::HoistAllocasBase<HoistAllocasPass> {
void runOnOperation() override;
};
+static bool isOpInLoop(mlir::Operation *op) {
+ return op->getParentOfType<cir::LoopOpInterface>();
+}
+
+static bool hasStoreToAllocaInWhileCond(cir::AllocaOp alloca) {
+ // This function determines whether the given alloca operation represents
+ // a variable defined as a while loop's condition.
+ //
+ // Specifically, C/C++ allows the condition of a while loop be a variable
+ // declaration:
+ //
+ // while (const int x = foo()) { /* body... */ }
+ //
+ // CIRGen would emit the following CIR for the above code:
+ //
+ // cir.scope {
+ // %x.slot = cir.alloca !s32i [init, const]
+ // cir.while {
+ // %0 = cir.call @foo()
+ // cir.store %0, %x
+ // %1 = cir.load %x
+ // %2 = cir.cast int_to_bool %1
+ // cir.condition(%2)
+ // } do {
+ // // loop body goes here.
+ // }
+ // }
+ //
+ // Note that %x.slot is emitted outside the cir.while operation. Ideally, the
+ // cir.while operation should cover this cir.alloca operation, but currently
+ // CIR does not work this way. When hoisting such an alloca operation, one
+ // must remove the "const" flag from it, otherwise LLVM lowering code will
+ // mistakenly attach invariant group metadata to the load and store
operations
+ // in the while body, indicating that all loads and stores across all
+ // iterations of the loop are constant.
+
+ for (mlir::Operation *user : alloca->getUsers()) {
+ if (!mlir::isa<cir::StoreOp>(user))
+ continue;
+
+ auto store = mlir::cast<cir::StoreOp>(user);
+ mlir::Operation *storeParentOp = store->getParentOp();
+ if (!mlir::isa<cir::WhileOp>(storeParentOp))
+ continue;
+
+ auto whileOp = mlir::cast<cir::WhileOp>(storeParentOp);
+ return &whileOp.getCond() == store->getParentRegion();
----------------
andykaylor wrote:
Is it possible for the store to occur in a sub-region within the while op's
condition region? Something with a compound expression maybe?
https://github.com/llvm/llvm-project/pull/175037
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