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Fixed a few spots where SkSL optimizer was not respecting side effects

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This was affecting expressions such as 0 * float4(<expr>), which would
be collapsed down to float4(0) - in some cases even if <expr> had side
effects. This is obviously incorrect no matter what, but to make matters
worse it could lead to a use-after-free when we eliminated an assignment
which we were tracking as the current definition of a variable.

Bug: skia:7467
Change-Id: I91ba154c57dad9cadf36b6062bec3211557248e0
Reviewed-on: https://skia-review.googlesource.com/98704
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
This commit is contained in:
Ethan Nicholas 2018-01-23 10:31:56 -05:00 committed by Skia Commit-Bot
parent d8327a8c8b
commit 08dae924f6
1 changed files with 6 additions and 3 deletions
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9
src/sksl/SkSLCompiler.cpp
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@ -713,7 +713,8 @@ void Compiler::simplifyExpression(DefinitionMap& definitions,
}
else if (is_constant(*bin->fLeft, 0)) {
if (bin->fLeft->fType.kind() == Type::kScalar_Kind &&
bin->fRight->fType.kind() == Type::kVector_Kind) {
bin->fRight->fType.kind() == Type::kVector_Kind &&
!bin->fRight->hasSideEffects()) {
// 0 * float4(x) -> float4(0)
vectorize_left(&b, iter, outUpdated, outNeedsRescan);
} else {
@ -739,7 +740,8 @@ void Compiler::simplifyExpression(DefinitionMap& definitions,
}
else if (is_constant(*bin->fRight, 0)) {
if (bin->fLeft->fType.kind() == Type::kVector_Kind &&
bin->fRight->fType.kind() == Type::kScalar_Kind) {
bin->fRight->fType.kind() == Type::kScalar_Kind &&
!bin->fLeft->hasSideEffects()) {
// float4(x) * 0 -> float4(0)
vectorize_right(&b, iter, outUpdated, outNeedsRescan);
} else {
@ -805,7 +807,8 @@ void Compiler::simplifyExpression(DefinitionMap& definitions,
}
} else if (is_constant(*bin->fLeft, 0)) {
if (bin->fLeft->fType.kind() == Type::kScalar_Kind &&
bin->fRight->fType.kind() == Type::kVector_Kind) {
bin->fRight->fType.kind() == Type::kVector_Kind &&
!bin->fRight->hasSideEffects()) {
// 0 / float4(x) -> float4(0)
vectorize_left(&b, iter, outUpdated, outNeedsRescan);
} else {