[Polly] Ensure i1 preload condition

If the preload condition is a constant, ExprBuilder::create returns an
integer of the native integer while an i1 is expected. Cast the result
to i1 if that happens.

Fixes llvm#123932

polly/include/polly/CodeGen/IslExprBuilder.h

@@ -135,6 +135,9 @@ class IslExprBuilder final {
   /// @return The llvm::Value* containing the result of the computation.
   llvm::Value *create(__isl_take isl_ast_expr *Expr);
 
+  /// Create LLVM-IR for an isl_ast_expr[ession] and cast it to i1.
+  llvm::Value *createBool(__isl_take isl_ast_expr *Expr);
+
   /// Return the largest of two types.
   ///
   /// @param T1 The first type.

polly/lib/CodeGen/IslExprBuilder.cpp

@@ -790,3 +790,10 @@ Value *IslExprBuilder::create(__isl_take isl_ast_expr *Expr) {
 
   llvm_unreachable("Unexpected enum value");
 }
+
+llvm::Value *IslExprBuilder::createBool(__isl_take isl_ast_expr *Expr) {
+  Value *Result = create(Expr);
+  if (!Result->getType()->isIntegerTy(1))
+    Result = Builder.CreateICmpNE(Result, Builder.getInt1(false));
+  return Result;
+}

polly/lib/CodeGen/IslNodeBuilder.cpp

@@ -1103,7 +1103,7 @@ Value *IslNodeBuilder::preloadInvariantLoad(const MemoryAccess &MA,
   Domain = nullptr;
 
   ExprBuilder.setTrackOverflow(true);
-  Value *Cond = ExprBuilder.create(DomainCond);
+  Value *Cond = ExprBuilder.createBool(DomainCond);
   Value *OverflowHappened = Builder.CreateNot(ExprBuilder.getOverflowState(),
                                               "polly.preload.cond.overflown");
   Cond = Builder.CreateAnd(Cond, OverflowHappened, "polly.preload.cond.result");