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Don't track bounds through wrapping casts in simplifier #7813

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Don't track bounds through wrapping casts in simplifier #7813

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051855b
Don't track bounds through wrapping casts in simplifier
abadams Aug 28, 2023
000884f
Merge remote-tracking branch 'origin/main' into abadams/fix_7811
abadams Nov 11, 2023
ed1a5dd
Merge branch 'main' into abadams/fix_7811
steven-johnson Nov 28, 2023
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18 changes: 5 additions & 13 deletions src/Simplify_Cast.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,20 +9,12 @@ Expr Simplify::visit(const Cast *op, ExprInfo *bounds) {
if (bounds) {
// If either the min value or the max value can't be represented
// in the destination type, or the min/max value is undefined,
// the bounds need to be cleared (one-sided for no_overflow,
// both sides for overflow types).
if ((bounds->min_defined && !op->type.can_represent(bounds->min)) || !bounds->min_defined) {
// the bounds need to be cleared.
if ((bounds->min_defined && !op->type.can_represent(bounds->min)) ||
!bounds->min_defined ||
(bounds->max_defined && !op->type.can_represent(bounds->max)) ||
!bounds->max_defined) {
bounds->min_defined = false;
if (!no_overflow(op->type)) {
// If the type overflows, this invalidates the max too.
bounds->max_defined = false;
}
}
if ((bounds->max_defined && !op->type.can_represent(bounds->max)) || !bounds->max_defined) {
if (!no_overflow(op->type)) {
// If the type overflows, this invalidates the min too.
bounds->min_defined = false;
}
bounds->max_defined = false;
}
if (!op->type.can_represent(bounds->alignment.modulus) ||
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6 changes: 6 additions & 0 deletions test/correctness/simplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

using namespace Halide;
using namespace Halide::Internal;
using namespace Halide::ConciseCasts;

#define internal_assert _halide_user_assert

Expand Down Expand Up @@ -1316,6 +1317,11 @@ void check_bounds() {
check(max(x * 4 + 63, y) - max(y - 3, x * 4), clamp(x * 4 - y, -63, -3) + 66);
check(max(x * 4, y - 3) - max(x * 4 + 63, y), clamp(y - x * 4, 3, 63) + -66);
check(max(y - 3, x * 4) - max(x * 4 + 63, y), clamp(y - x * 4, 3, 63) + -66);

// Check the simplifier doesn't make constant-bounds-based simplifications
// through potentially-wrapping casts.
check(max(i32(select(x == 0, u32(0), u32(Expr(0x80000000U)))), -1),
max(i32(select(x == 0, u32(0), u32(Expr(0x80000000U)))), -1));
}

void check_boolean() {
Expand Down