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Fix undefined behavior in gameexec.cpp

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git-svn-id: https://svn.eduke32.com/eduke32@6542 1a8010ca-5511-0410-912e-c29ae57300e0
This commit is contained in:
terminx 2017-12-09 02:56:05 +00:00
parent 3c8f050565
commit 948fe80304
1 changed files with 19 additions and 26 deletions
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45
source/duke3d/src/gameexec.cpp
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@ -166,38 +166,30 @@ static void VM_DummySprite(void)
static FORCE_INLINE int32_t VM_EventCommon_(int const eventNum, int const spriteNum, int const playerNum,
int const playerDist, int32_t returnValue)
{
// this is initialized first thing because spriteNum, playerNum, lDist, etc are already right there on the stack
// from the function call
const vmstate_t tempvm = { spriteNum,
playerNum,
playerDist,
0,
&sprite[(unsigned)spriteNum],
&actor[(unsigned)spriteNum].t_data[0],
g_player[playerNum].ps,
&actor[(unsigned) spriteNum] };
const vmstate_t tempvm = { spriteNum, playerNum, playerDist, 0, NULL, NULL, g_player[playerNum].ps, NULL };
// since we're targeting C99 and C++ now, we can interweave these to avoid
// having to load addresses for things twice
// for example, because we are loading backupReturnVar with the value of
// aGameVars[g_iReturnVarID].lValue, the compiler can avoid having to
// reload the address of aGameVars[g_iReturnVarID].lValue in order to
// set it to the value of iReturn (...which should still be on the stack!)
int const backupReturnVar = aGameVars[g_returnVarID].global;
int const backupEventExec = g_currentEventExec;
int const backupReturnVar = aGameVars[g_returnVarID].global;
aGameVars[g_returnVarID].global = returnValue;
int const backupEventExec = g_currentEventExec;
g_currentEventExec = eventNum;
intptr_t const *oinsptr = insptr;
insptr = apScript + apScriptEvents[eventNum];
const vmstate_t vm_backup = vm;
vm = tempvm;
intptr_t const *oinsptr = insptr;
const vmstate_t vm_backup = vm;
insptr = apScript + apScriptEvents[eventNum];
vm = tempvm;
// check tempvm instead of vm... this way, we are not actually loading
// FROM vm anywhere until VM_Execute() is called
if (EDUKE32_PREDICT_FALSE((unsigned) tempvm.spriteNum >= MAXSPRITES))
VM_DummySprite();
else
{
vm.pSprite = &sprite[spriteNum];
vm.pActor = &actor[spriteNum];
vm.pData = &actor[spriteNum].t_data[0];
}
if ((unsigned)playerNum >= (unsigned)g_mostConcurrentPlayers)
vm.pPlayer = g_player[0].ps;
@ -210,10 +202,11 @@ static FORCE_INLINE int32_t VM_EventCommon_(int const eventNum, int const sprite
// this needs to happen after VM_DeleteSprite() because VM_DeleteSprite()
// can trigger additional events
vm = vm_backup;
insptr = oinsptr;
g_currentEventExec = backupEventExec;
returnValue = aGameVars[g_returnVarID].global;
vm = vm_backup;
insptr = oinsptr;
g_currentEventExec = backupEventExec;
returnValue = aGameVars[g_returnVarID].global;
aGameVars[g_returnVarID].global = backupReturnVar;
return returnValue;