Dynamic protocols. Correctly widen unsigned array indices (see #1029)

c3lang · Oct 5, 2023 · e198d3d · e198d3d
1 parent a6bd9aa
commit e198d3d
Show file tree

Hide file tree

Showing 4 changed files with 31 additions and 15 deletions.
diff --git a/releasenotes.md b/releasenotes.md
@@ -173,6 +173,7 @@
 - Added posix socket functions.
 
 ### Fixes
+- Indexing into arrays would not always widen the index safely.
 - Macros with implicit return didn't correctly deduct the return type.
 - Reevaluating a bitstruct (due to checked) would break.
 - Fix missing comparison between `any`.

diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
@@ -606,7 +606,7 @@ static inline void llvm_emit_subscript_addr_with_base(GenContext *c, BEValue *re
 		case TYPE_VECTOR:
 		{
 			AlignSize alignment;
-			LLVMValueRef ptr = llvm_emit_array_gep_raw_index(c, parent->value, llvm_get_type(c, type), index->value, parent->alignment, &alignment);
+			LLVMValueRef ptr = llvm_emit_array_gep_raw_index(c, parent->value, llvm_get_type(c, type), index, parent->alignment, &alignment);
 			llvm_value_set_address(result, ptr, type->array.base, alignment);
 			return;
 		}
@@ -1167,7 +1167,7 @@ static inline void llvm_emit_access_addr(GenContext *c, BEValue *be_value, Expr
 		LLVMTypeRef value_type = llvm_get_type(c, type_get_array(member->type, vec_size(flat_type->decl->enums.values)));
 		AlignSize align = LLVMGetAlignment(member->backend_ref);
 		AlignSize alignment;
-		LLVMValueRef ptr = llvm_emit_array_gep_raw_index(c, member->backend_ref, value_type, be_value->value, align, &alignment);
+		LLVMValueRef ptr = llvm_emit_array_gep_raw_index(c, member->backend_ref, value_type, be_value, align, &alignment);
 		llvm_value_set_address(be_value, ptr, member->type, alignment);
 		return;
 	}
@@ -2966,7 +2966,7 @@ static void gencontext_emit_slice(GenContext *c, BEValue *be_value, Expr *expr)
 		{
 			// Move pointer
 			AlignSize alignment;
-			start_pointer = llvm_emit_array_gep_raw_index(c, parent.value, llvm_get_type(c, parent.type), start.value, type_abi_alignment(parent.type), &alignment);
+			start_pointer = llvm_emit_array_gep_raw_index(c, parent.value, llvm_get_type(c, parent.type), &start, type_abi_alignment(parent.type), &alignment);
 			break;
 		}
 		case TYPE_SUBARRAY:
@@ -3656,20 +3656,21 @@ static void llvm_emit_array_comp(GenContext *c, BEValue *be_value, BEValue *lhs,
 
 	AlignSize align_lhs;
 	BEValue lhs_v;
-	LLVMValueRef index = llvm_load_value(c, &index_var);
-	LLVMValueRef lhs_ptr = llvm_emit_array_gep_raw_index(c, lhs->value, array_type, index, lhs->alignment, &align_lhs);
+	BEValue index_copy = index_var;
+	llvm_value_rvalue(c, &index_copy);
+	LLVMValueRef lhs_ptr = llvm_emit_array_gep_raw_index(c, lhs->value, array_type, &index_copy, lhs->alignment, &align_lhs);
 	llvm_value_set_address(&lhs_v, lhs_ptr, array_base_type, align_lhs);
 	AlignSize align_rhs;
 	BEValue rhs_v;
-	LLVMValueRef rhs_ptr = llvm_emit_array_gep_raw_index(c, rhs->value, array_type, index, rhs->alignment, &align_rhs);
+	LLVMValueRef rhs_ptr = llvm_emit_array_gep_raw_index(c, rhs->value, array_type, &index_copy, rhs->alignment, &align_rhs);
 	llvm_value_set_address(&rhs_v, rhs_ptr, array_base_type, align_rhs);
 	BEValue comp;
 	llvm_emit_comp(c, &comp, &lhs_v, &rhs_v, BINARYOP_EQ);
 	loop_begin_phi = c->current_block;
 	llvm_emit_cond_br(c, &comp, comparison, exit);
 	llvm_emit_block(c, comparison);
 
-	LLVMValueRef new_index = LLVMBuildAdd(c->builder, index, one, "inc");
+	LLVMValueRef new_index = LLVMBuildAdd(c->builder, index_copy.value, one, "inc");
 	llvm_store_raw(c, &index_var, new_index);
 	llvm_emit_int_comp_raw(c, &comp, type_usz, type_usz, new_index, len_val, BINARYOP_LT);
 	comparison_phi = c->current_block;
@@ -4948,16 +4949,26 @@ LLVMValueRef llvm_emit_struct_gep_raw(GenContext *context, LLVMValueRef ptr, LLV
 }
 
 
-LLVMValueRef llvm_emit_array_gep_raw_index(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, LLVMValueRef index, AlignSize array_alignment, AlignSize *alignment)
+LLVMValueRef llvm_emit_array_gep_raw_index(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, BEValue *index, AlignSize array_alignment, AlignSize *alignment)
 {
+	LLVMValueRef index_val = llvm_load_value(c, index);
+	Type *index_type = index->type;
+	assert(type_is_integer(index_type));
+	if (type_is_unsigned(index_type) && type_size(index_type) < type_size(type_usz))
+	{
+		index_type = type_usz->canonical;
+		index_val = llvm_zext_trunc(c, index_val, llvm_get_type(c, index_type));
+	}
 	*alignment = type_min_alignment(llvm_store_size(c, LLVMGetElementType(array_type)), array_alignment);
-	LLVMValueRef idx[2] = { llvm_get_zero_raw(LLVMTypeOf(index)), index };
+	LLVMValueRef idx[2] = { llvm_get_zero(c, index_type), index_val };
 	return LLVMBuildInBoundsGEP2(c->builder, array_type, ptr, idx, 2, "");
 }
 
 LLVMValueRef llvm_emit_array_gep_raw(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, unsigned index, AlignSize array_alignment, AlignSize *alignment)
 {
-	return llvm_emit_array_gep_raw_index(c, ptr, array_type, llvm_const_int(c, type_usz, index), array_alignment, alignment);
+	BEValue index_value;
+	llvm_value_set(&index_value, llvm_const_int(c, type_usz, index), type_usz);
+	return llvm_emit_array_gep_raw_index(c, ptr, array_type, &index_value, array_alignment, alignment);
 }
 
 LLVMValueRef llvm_emit_pointer_gep_raw(GenContext *c, LLVMTypeRef pointee_type, LLVMValueRef ptr, LLVMValueRef offset)

diff --git a/src/compiler/llvm_codegen_internal.h b/src/compiler/llvm_codegen_internal.h
@@ -452,7 +452,7 @@ LLVMValueRef llvm_emit_aggregate_two(GenContext *c, Type *type, LLVMValueRef val
 LLVMValueRef llvm_emit_struct_gep_raw(GenContext *context, LLVMValueRef ptr, LLVMTypeRef struct_type, unsigned index,
 									  unsigned struct_alignment, AlignSize *alignment);
 LLVMValueRef llvm_emit_array_gep_raw(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, unsigned index, AlignSize array_alignment, AlignSize *alignment);
-LLVMValueRef llvm_emit_array_gep_raw_index(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, LLVMValueRef index, AlignSize array_alignment, AlignSize *alignment);
+LLVMValueRef llvm_emit_array_gep_raw_index(GenContext *c, LLVMValueRef ptr, LLVMTypeRef array_type, BEValue *index, AlignSize array_alignment, AlignSize *alignment);
 LLVMValueRef llvm_emit_pointer_gep_raw(GenContext *c, LLVMTypeRef pointee_type, LLVMValueRef ptr, LLVMValueRef offset);
 LLVMValueRef llvm_emit_pointer_inbounds_gep_raw(GenContext *c, LLVMTypeRef pointee_type, LLVMValueRef ptr, LLVMValueRef offset);
 LLVMValueRef llvm_emit_pointer_inbounds_gep_raw_index(GenContext *c, LLVMTypeRef pointee_type, LLVMValueRef ptr, ByteSize offset);

diff --git a/test/test_suite/enumerations/enum_associated_value.c3t b/test/test_suite/enumerations/enum_associated_value.c3t
@@ -39,16 +39,20 @@ entry:
   store i32 1, ptr %f, align 4
   store i32 0, ptr %g, align 4
   %0 = load i32, ptr %f, align 4
-  %1 = getelementptr inbounds [2 x i32], ptr @"test.Foo$val", i32 0, i32 %0
+  %zext = zext i32 %0 to i64
+  %1 = getelementptr inbounds [2 x i32], ptr @"test.Foo$val", i64 0, i64 %zext
   %2 = load i32, ptr %1, align 4
   %3 = load i32, ptr %f, align 4
-  %4 = getelementptr inbounds [2 x ptr], ptr @"test.Foo$testme", i32 0, i32 %3
+  %zext1 = zext i32 %3 to i64
+  %4 = getelementptr inbounds [2 x ptr], ptr @"test.Foo$testme", i64 0, i64 %zext1
   %5 = load ptr, ptr %4, align 8
   %6 = load i32, ptr %g, align 4
-  %7 = getelementptr inbounds [2 x i32], ptr @"test.Foo$val", i32 0, i32 %6
+  %zext2 = zext i32 %6 to i64
+  %7 = getelementptr inbounds [2 x i32], ptr @"test.Foo$val", i64 0, i64 %zext2
   %8 = load i32, ptr %7, align 4
   %9 = load i32, ptr %g, align 4
-  %10 = getelementptr inbounds [2 x ptr], ptr @"test.Foo$testme", i32 0, i32 %9
+  %zext3 = zext i32 %9 to i64
+  %10 = getelementptr inbounds [2 x ptr], ptr @"test.Foo$testme", i64 0, i64 %zext3
   %11 = load ptr, ptr %10, align 8
   %12 = call i32 (ptr, ...) @printf(ptr @.str.2, i32 %2, ptr %5, i32 %8, ptr %11)
   ret void