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Fix undefined evaluation order when constructing random vectors 

MSVC and GCC evaluate parameters in right-to-left order, whereas Clang
evaluates in left-to-right order, and of course, an optimization could
leave the order of evaluation completely indeterminate.

This commit fixes all instances of the error by explicitly assigning the
results of expressions that use PseudoRandom::next() or range() to their
respective vector components.

The right-to-left evaluation behavior is preserved since Clang is much less
commonly used to compile Minetest than GCC and MSVC combined, and would
therefore cause the least harm.
master
kwolekr 2016-05-11 03:47:45 -04:00
parent 5b05f75a27
commit b1eb757e60
2 changed files with 47 additions and 49 deletions
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67
src/cavegen.cpp
View File

@ -133,11 +133,9 @@ void CavesRandomWalk::makeCave(MMVManip *vm, v3s16 nmin, v3s16 nmax,
route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y - 1); route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y - 1);
// Randomize starting position // Randomize starting position
orp = v3f( orp.Z = (float)(ps->next() % ar.Z) + 0.5;
(float)(ps->next() % ar.X) + 0.5, orp.Y = (float)(ps->range(route_start_y_min, route_start_y_max)) + 0.5;
(float)(ps->range(route_start_y_min, route_start_y_max)) + 0.5, orp.X = (float)(ps->next() % ar.X) + 0.5;
(float)(ps->next() % ar.Z) + 0.5
);
// Add generation notify begin event // Add generation notify begin event
if (gennotify) { if (gennotify) {
@ -164,11 +162,10 @@ void CavesRandomWalk::makeCave(MMVManip *vm, v3s16 nmin, v3s16 nmax,
void CavesRandomWalk::makeTunnel(bool dirswitch) void CavesRandomWalk::makeTunnel(bool dirswitch)
{ {
if (dirswitch && !large_cave) { if (dirswitch && !large_cave) {
main_direction = v3f( main_direction.Z = ((float)(ps->next() % 20) - (float)10) / 10;
((float)(ps->next() % 20) - (float)10) / 10, main_direction.Y = ((float)(ps->next() % 20) - (float)10) / 30;
((float)(ps->next() % 20) - (float)10) / 30, main_direction.X = ((float)(ps->next() % 20) - (float)10) / 10;
((float)(ps->next() % 20) - (float)10) / 10
);
main_direction *= (float)ps->range(0, 10) / 10; main_direction *= (float)ps->range(0, 10) / 10;
} }
@ -196,17 +193,13 @@ void CavesRandomWalk::makeTunnel(bool dirswitch)
v3f vec; v3f vec;
// Jump downward sometimes // Jump downward sometimes
if (!large_cave && ps->range(0, 12) == 0) { if (!large_cave && ps->range(0, 12) == 0) {
vec = v3f( vec.Z = (float)(ps->next() % (maxlen.Z * 1)) - (float)maxlen.Z / 2;
(float)(ps->next() % (maxlen.X * 1)) - (float)maxlen.X / 2, vec.Y = (float)(ps->next() % (maxlen.Y * 2)) - (float)maxlen.Y;
(float)(ps->next() % (maxlen.Y * 2)) - (float)maxlen.Y, vec.X = (float)(ps->next() % (maxlen.X * 1)) - (float)maxlen.X / 2;
(float)(ps->next() % (maxlen.Z * 1)) - (float)maxlen.Z / 2
);
} else { } else {
vec = v3f( vec.Z = (float)(ps->next() % (maxlen.Z * 1)) - (float)maxlen.Z / 2;
(float)(ps->next() % (maxlen.X * 1)) - (float)maxlen.X / 2, vec.Y = (float)(ps->next() % (maxlen.Y * 1)) - (float)maxlen.Y / 2;
(float)(ps->next() % (maxlen.Y * 1)) - (float)maxlen.Y / 2, vec.X = (float)(ps->next() % (maxlen.X * 1)) - (float)maxlen.X / 2;
(float)(ps->next() % (maxlen.Z * 1)) - (float)maxlen.Z / 2
);
} }
// Do not make caves that are above ground. // Do not make caves that are above ground.
@ -446,11 +439,9 @@ void CavesV6::makeCave(MMVManip *vm, v3s16 nmin, v3s16 nmax,
route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y - 1); route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y - 1);
// Randomize starting position // Randomize starting position
orp = v3f( orp.Z = (float)(ps->next() % ar.Z) + 0.5;
(float)(ps->next() % ar.X) + 0.5, orp.Y = (float)(ps->range(route_start_y_min, route_start_y_max)) + 0.5;
(float)(ps->range(route_start_y_min, route_start_y_max)) + 0.5, orp.X = (float)(ps->next() % ar.X) + 0.5;
(float)(ps->next() % ar.Z) + 0.5
);
// Add generation notify begin event // Add generation notify begin event
if (gennotify != NULL) { if (gennotify != NULL) {
@ -477,11 +468,10 @@ void CavesV6::makeCave(MMVManip *vm, v3s16 nmin, v3s16 nmax,
void CavesV6::makeTunnel(bool dirswitch) void CavesV6::makeTunnel(bool dirswitch)
{ {
if (dirswitch && !large_cave) { if (dirswitch && !large_cave) {
main_direction = v3f( main_direction.Z = ((float)(ps->next() % 20) - (float)10) / 10;
((float)(ps->next() % 20) - (float)10) / 10, main_direction.Y = ((float)(ps->next() % 20) - (float)10) / 30;
((float)(ps->next() % 20) - (float)10) / 30, main_direction.X = ((float)(ps->next() % 20) - (float)10) / 10;
((float)(ps->next() % 20) - (float)10) / 10
);
main_direction *= (float)ps->range(0, 10) / 10; main_direction *= (float)ps->range(0, 10) / 10;
} }
@ -506,19 +496,16 @@ void CavesV6::makeTunnel(bool dirswitch)
); );
} }
v3f vec( v3f vec;
(float)(ps->next() % maxlen.X) - (float)maxlen.X / 2, vec.Z = (float)(ps->next() % maxlen.Z) - (float)maxlen.Z / 2;
(float)(ps->next() % maxlen.Y) - (float)maxlen.Y / 2, vec.Y = (float)(ps->next() % maxlen.Y) - (float)maxlen.Y / 2;
(float)(ps->next() % maxlen.Z) - (float)maxlen.Z / 2 vec.X = (float)(ps->next() % maxlen.X) - (float)maxlen.X / 2;
);
// Jump downward sometimes // Jump downward sometimes
if (!large_cave && ps->range(0, 12) == 0) { if (!large_cave && ps->range(0, 12) == 0) {
vec = v3f( vec.Z = (float)(ps->next() % maxlen.Z) - (float)maxlen.Z / 2;
(float)(ps->next() % maxlen.X) - (float)maxlen.X / 2, vec.Y = (float)(ps->next() % (maxlen.Y * 2)) - (float)maxlen.Y;
(float)(ps->next() % (maxlen.Y * 2)) - (float)maxlen.Y, vec.X = (float)(ps->next() % maxlen.X) - (float)maxlen.X / 2;
(float)(ps->next() % maxlen.Z) - (float)maxlen.Z / 2
);
} }
// Do not make caves that are entirely above ground, to fix shadow bugs // Do not make caves that are entirely above ground, to fix shadow bugs

29
src/dungeongen.cpp
View File

@ -135,17 +135,23 @@ void DungeonGen::makeDungeon(v3s16 start_padding)
bool fits = false; bool fits = false;
for (u32 i = 0; i < 100 && !fits; i++) { for (u32 i = 0; i < 100 && !fits; i++) {
bool is_large_room = ((random.next() & 3) == 1); bool is_large_room = ((random.next() & 3) == 1);
roomsize = is_large_room ? if (is_large_room) {
v3s16(random.range(8, 16), random.range(8, 16), random.range(8, 16)) : roomsize.Z = random.range(8, 16);
v3s16(random.range(4, 8), random.range(4, 6), random.range(4, 8)); roomsize.Y = random.range(8, 16);
roomsize.X = random.range(8, 16);
} else {
roomsize.Z = random.range(4, 8);
roomsize.Y = random.range(4, 6);
roomsize.X = random.range(4, 8);
}
roomsize += dp.roomsize; roomsize += dp.roomsize;
// start_padding is used to disallow starting the generation of // start_padding is used to disallow starting the generation of
// a dungeon in a neighboring generation chunk // a dungeon in a neighboring generation chunk
roomplace = vm->m_area.MinEdge + start_padding + v3s16( roomplace = vm->m_area.MinEdge + start_padding;
random.range(0, areasize.X - roomsize.X - start_padding.X), roomplace.Z += random.range(0, areasize.Z - roomsize.Z - start_padding.Z);
random.range(0, areasize.Y - roomsize.Y - start_padding.Y), roomplace.Y += random.range(0, areasize.Y - roomsize.Y - start_padding.Y);
random.range(0, areasize.Z - roomsize.Z - start_padding.Z)); roomplace.X += random.range(0, areasize.X - roomsize.X - start_padding.X);
/* /*
Check that we're not putting the room to an unknown place, Check that we're not putting the room to an unknown place,
@ -227,7 +233,9 @@ void DungeonGen::makeDungeon(v3s16 start_padding)
makeCorridor(doorplace, doordir, corridor_end, corridor_end_dir); makeCorridor(doorplace, doordir, corridor_end, corridor_end_dir);
// Find a place for a random sized room // Find a place for a random sized room
roomsize = v3s16(random.range(4, 8), random.range(4, 6), random.range(4, 8)); roomsize.Z = random.range(4, 8);
roomsize.Y = random.range(4, 6);
roomsize.X = random.range(4, 8);
roomsize += dp.roomsize; roomsize += dp.roomsize;
m_pos = corridor_end; m_pos = corridor_end;
@ -587,7 +595,10 @@ v3s16 rand_ortho_dir(PseudoRandom &random, bool diagonal_dirs)
do { do {
trycount++; trycount++;
dir = v3s16(random.next() % 3 - 1, 0, random.next() % 3 - 1);
dir.Z = random.next() % 3 - 1;
dir.Y = 0;
dir.X = random.next() % 3 - 1;
} while ((dir.X == 0 && dir.Z == 0) && trycount < 10); } while ((dir.X == 0 && dir.Z == 0) && trycount < 10);
return dir; return dir;