Boolean array literals read back their own elements

tslang/include/TypeScript/LowerToLLVM/LLVMCodeHelper.h

@@ -575,8 +575,15 @@ class LLVMCodeHelper : public LLVMCodeHelperBase
             DenseElementsAttr denseAttr;
             if (isDense)
             {
-                auto vectorType = mlir::VectorType::get({static_cast<int64_t>(value.size())}, llvmElementType);
-                dataType = vectorType;
+                // A vector of elements narrower than a byte (a boolean's i1) is packed into bits, but
+                // array elements are read one byte apart: `[false, true]` read back as garbage. Such
+                // data is an array, laid out a byte per element, like the elements it is copied to.
+                auto shapeSize = static_cast<int64_t>(value.size());
+                auto packedIntoBits = llvmElementType.isInteger() && llvmElementType.getIntOrFloatBitWidth() % 8 != 0;
+                mlir::ShapedType shapedType = packedIntoBits
+                    ? (mlir::ShapedType)mlir::RankedTensorType::get({shapeSize}, llvmElementType)
+                    : (mlir::ShapedType)mlir::VectorType::get({shapeSize}, llvmElementType);
+                dataType = packedIntoBits ? arrayType : (mlir::Type)shapedType;
 
                 if (llvmElementType.isIntOrIndex())
                 {
@@ -585,7 +592,7 @@ class LLVMCodeHelper : public LLVMCodeHelperBase
                         values.push_back(cast<mlir::IntegerAttr>(value_).getValue());
                     });
 
-                    denseAttr = DenseElementsAttr::get(vectorType, values);
+                    denseAttr = DenseElementsAttr::get(shapedType, values);
                 }
                 else
                 {
@@ -594,7 +601,7 @@ class LLVMCodeHelper : public LLVMCodeHelperBase
                         values.push_back(cast<mlir::FloatAttr>(value_).getValue());
                     });
 
-                    denseAttr = DenseElementsAttr::get(vectorType, values);
+                    denseAttr = DenseElementsAttr::get(shapedType, values);
                 }
             }
 

tslang/test/tester/CMakeLists.txt

@@ -271,6 +271,7 @@ tslang_add_test(NAME test-compile-01-enums COMMAND test-runner "${PROJECT_SOURCE
 tslang_add_test(NAME test-compile-00-numbers COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00numbers.ts")
 tslang_add_test(NAME test-compile-00-equals COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00equals.ts")
 tslang_add_test(NAME test-compile-00-bool-arith-ops COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_arith_ops.ts")
+tslang_add_test(NAME test-compile-00-bool-const-array COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_const_array.ts")
 tslang_add_test(NAME test-compile-00-mixed-type-ops COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00mixed_type_ops.ts")
 tslang_add_test(NAME test-compile-00-generator-manual-next COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_manual_next.ts")
 tslang_add_test(NAME test-compile-00-generator-manual-next-2 COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_manual_next2.ts")
@@ -791,6 +792,7 @@ tslang_add_test(NAME test-jit-01-enums COMMAND test-runner -jit "${PROJECT_SOURC
 tslang_add_test(NAME test-jit-00-numbers COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00numbers.ts")
 tslang_add_test(NAME test-jit-00-equals COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00equals.ts")
 tslang_add_test(NAME test-jit-00-bool-arith-ops COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_arith_ops.ts")
+tslang_add_test(NAME test-jit-00-bool-const-array COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00bool_const_array.ts")
 tslang_add_test(NAME test-jit-00-mixed-type-ops COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00mixed_type_ops.ts")
 tslang_add_test(NAME test-jit-00-generator-manual-next COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_manual_next.ts")
 tslang_add_test(NAME test-jit-00-generator-manual-next-2 COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_manual_next2.ts")
@@ -1745,6 +1747,7 @@ set(TSLANG_CORPUS
     00async_gc_threading.ts
     00async_result_types.ts
     00bool_arith_ops.ts
+    00bool_const_array.ts
     00break_continue_scope_exit.ts
     00break_continue.ts
     00capture_in_new_arguments.ts

tslang/test/tester/tests/00bool_const_array.ts

@@ -0,0 +1,53 @@
+// The elements of a boolean array literal read back wrong: the constant data was an LLVM vector of
+// i1, which packs its elements into bits, while elements are read one byte apart. So `if (F[i])`
+// was never taken, a count of the true elements came out as 10 for four elements, and F[1] was
+// false.
+
+const FLAGS = [false, true, false, true];
+
+function countTrue(flags: boolean[]) {
+    let n = 0;
+    for (let i = 0; i < flags.length; i++) {
+        if (flags[i]) {
+            n++;
+        }
+    }
+
+    return n;
+}
+
+function locals() {
+    let a = [true, false, true];
+    assert(a[0], "a[0]");
+    assert(!a[1], "a[1]");
+    assert(a[2], "a[2]");
+
+    let n = 0;
+    for (const x of a) {
+        if (x) n++;
+    }
+
+    assert(n == 2, "for-of count");
+}
+
+function many() {
+    // more elements than fit in a byte of bits
+    const m = [true, false, false, true, true, false, true, false, true, true, false, true];
+    assert(countTrue(m) == 7, "twelve elements");
+    assert(m[11], "m[11]");
+    assert(!m[10], "m[10]");
+}
+
+function main() {
+    assert(FLAGS.length == 4, "length");
+    assert(countTrue(FLAGS) == 2, "count");
+    const b: boolean = FLAGS[1];
+    assert(b, "FLAGS[1]");
+    assert(!FLAGS[0], "FLAGS[0]");
+    assert(FLAGS[3], "FLAGS[3]");
+
+    locals();
+    many();
+
+    print("done.");
+}