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scripts: resolve strict aliasing violations in level DLLs

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$GIT/scripts/LEVEL15.cpp: In function ‘void aMatCenPuzzleInit()’:
$GIT/scripts/LEVEL15.cpp:833:38: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  833 | #define MagicMatCenSwitchSequence (*((int *)(&User_vars[17])))
$GIT/scripts/LEVEL15.cpp:834:25: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  834 | #define MatCenStateA (*((int *)(&User_vars[0])))
...
$GIT/scripts/Level6.cpp: In function ‘void aPriestKeyEnter(int)’:
$GIT/scripts/Level6.cpp:910:47: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  910 | #define Var_ThereIsPlayerInPriestKeyPuzzle (*((int *)(&User_vars[7])))

Turn ``User_var`` into an array of std::variant, the latter of which can hold
either float or int. Savegames do not carry the necessary type information
which variant (float/int) is in use; instead, this is statically decided by
the level DLL logic on a per-index basis. This approach is retained for now.

A lot of ``Var_something = 0`` is used despite Var_something being
logically used as float, so we need to override op= to keep the
variant type as-is.
This commit is contained in:
Jan Engelhardt
2024-09-03 11:49:20 +02:00
parent b6ef3b591a
commit e867977543
4 changed files with 99 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
scripts/DallasFuncs.cpp
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@@ -708,6 +708,9 @@
*
*/
#include <algorithm>
#include <climits>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <cstdarg>
@@ -913,7 +916,7 @@ $$END
// Variables
//
float User_vars[MAX_USER_VARS];
std::vector<user_var> User_vars(MAX_USER_VARS);
int Spew_handles[MAX_SPEW_HANDLES];
#define MAX_SOUND_HANDLES 10 // make sure this value matches the USERTYPE definition
@@ -955,7 +958,7 @@ $$USERTYPE SavedObjectSlot:19
//
// Initialize vars
void dfInit() {
void dfInit(const std::initializer_list<int> &uv_int) {
int i;
for (i = 0; i < MAX_SPEW_HANDLES; i++)
@@ -966,6 +969,8 @@ void dfInit() {
for (i = 0; i < MAX_USER_VARS; i++)
User_vars[i] = 0.0;
for (auto idx : uv_int)
User_vars[idx].set_type<int32_t>();
for (i = 0; i < MAX_SAVED_OBJECT_HANDLES; i++)
Saved_object_handles[i] = OBJECT_HANDLE_NONE;
@@ -983,8 +988,12 @@ void dfSave(void *fileptr) {
for (i = 0; i < MAX_SOUND_HANDLES; i++)
File_WriteInt(Sound_handles[i], fileptr);
for (i = 0; i < MAX_USER_VARS; i++)
File_WriteFloat(User_vars[i], fileptr);
for (i = 0; i < MAX_USER_VARS; i++) {
if (const auto *value = std::get_if<float>(&User_vars[i]))
File_WriteFloat(*value, fileptr);
else
File_WriteInt(std::get<int32_t>(User_vars[i]), fileptr);
}
for (i = 0; i < MAX_SAVED_OBJECT_HANDLES; i++)
File_WriteInt(Saved_object_handles[i], fileptr);
@@ -1018,7 +1027,10 @@ void dfRestore(void *fileptr) {
Sound_handles[i] = File_ReadInt(fileptr);
for (i = 0; i < MAX_USER_VARS; i++)
User_vars[i] = File_ReadFloat(fileptr);
if (std::get_if<int32_t>(&User_vars[i]))
User_vars[i] = File_ReadInt(fileptr);
else
User_vars[i] = File_ReadFloat(fileptr);
for (i = 0; i < MAX_SAVED_OBJECT_HANDLES; i++)
Saved_object_handles[i] = File_ReadInt(fileptr);
@@ -5514,10 +5526,11 @@ Parameters:
$$END
*/
float qUserVarValue(int varnum) {
if ((varnum >= 0) && (varnum < MAX_USER_VARS))
return User_vars[varnum];
else
return 0.0;
if (varnum < 0 || varnum >= MAX_USER_VARS)
return 0;
if (const auto *value = std::get_if<int32_t>(&User_vars[varnum]))
return *value;
return std::get<float>(User_vars[varnum]);
}
/*
@@ -5533,10 +5546,17 @@ Parameters:
$$END
*/
int qUserVarValueInt(int varnum) {
if ((varnum >= 0) && (varnum < MAX_USER_VARS))
return (User_vars[varnum] + 0.5);
else
return 0.0;
if (varnum < 0 || varnum >= MAX_USER_VARS)
return 0;
if (const auto *value = std::get_if<int32_t>(&User_vars[varnum]))
return *value;
auto value = std::get<float>(User_vars[varnum]);
// Check boundaries first, else float=>int conversion is UB
if (value < std::nexttoward(INT_MIN, 0))
return INT_MIN;
if (value >= std::nexttoward(INT_MAX, 0))
return INT_MAX;
return value + 0.5;
}
/*