Miscompile when indexing an array with small unsigned types.

Author: lerno

releasenotes.md

@@ -29,6 +29,7 @@
 - Use `weak_odr` rather than `weak` on Windows which seems to prevent issues such as #1704.
 - Use `weak` on dyn-symbols on Linux.
 - Fix crash on project.json not having an empty set of targets.
+- Miscompile when indexing an array with small unsigned types for enums.
 
 ### Stdlib changes
 - Increase BitWriter.write_bits limit up to 32 bits.

src/compiler/llvm_codegen_expr.c

@@ -5292,10 +5292,9 @@ LLVMValueRef llvm_emit_array_gep_raw_index(GenContext *c, LLVMValueRef ptr, LLVM
 	LLVMTypeRef element_type = LLVMGetElementType(array_type);
 	Type *index_type = index->type;
 	ASSERT0(type_is_integer(index_type));
-	LLVMTypeRef idx_type = llvm_get_type(c, index_type);
 	if (type_is_unsigned(index_type) && type_size(index_type) < type_size(type_usz))
 	{
-		index_val = llvm_zext_trunc(c, index_val, idx_type);
+		index_val = llvm_zext_trunc(c, index_val, llvm_get_type(c, type_usz));
 	}
 	*alignment = type_min_alignment(llvm_abi_size(c, element_type), array_alignment);
 	return llvm_emit_pointer_inbounds_gep_raw(c, element_type, ptr, index_val);

test/test_suite/enumerations/enum_associated_value.c3t

@@ -41,17 +41,21 @@ entry:
   store i32 1, ptr %f, align 4
   store i32 0, ptr %g, align 4
   %0 = load i32, ptr %f, align 4
-  %ptroffset = getelementptr inbounds [4 x i8], ptr @"test.Foo$val", i32 %0
+  %zext = zext i32 %0 to i64
+  %ptroffset = getelementptr inbounds [4 x i8], ptr @"test.Foo$val", i64 %zext
   %1 = load i32, ptr %f, align 4
-  %ptroffset1 = getelementptr inbounds [8 x i8], ptr @"test.Foo$testme", i32 %1
+  %zext1 = zext i32 %1 to i64
+  %ptroffset2 = getelementptr inbounds [8 x i8], ptr @"test.Foo$testme", i64 %zext1
   %2 = load i32, ptr %g, align 4
-  %ptroffset2 = getelementptr inbounds [4 x i8], ptr @"test.Foo$val", i32 %2
+  %zext3 = zext i32 %2 to i64
+  %ptroffset4 = getelementptr inbounds [4 x i8], ptr @"test.Foo$val", i64 %zext3
   %3 = load i32, ptr %g, align 4
-  %ptroffset3 = getelementptr inbounds [8 x i8], ptr @"test.Foo$testme", i32 %3
+  %zext5 = zext i32 %3 to i64
+  %ptroffset6 = getelementptr inbounds [8 x i8], ptr @"test.Foo$testme", i64 %zext5
   %4 = load i32, ptr %ptroffset, align 4
-  %5 = load ptr, ptr %ptroffset1, align 8
-  %6 = load i32, ptr %ptroffset2, align 4
-  %7 = load ptr, ptr %ptroffset3, align 8
+  %5 = load ptr, ptr %ptroffset2, align 8
+  %6 = load i32, ptr %ptroffset4, align 4
+  %7 = load ptr, ptr %ptroffset6, align 8
   %8 = call i32 (ptr, ...) @printf(ptr @.str.2, i32 %4, ptr %5, i32 %6, ptr %7)
   ret void
 }