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Merge pull request #75 from google/fix-vs2013-debug

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SPV non-determinism: Fixed subtle issue that causes tests to fail in VS2013 in some configs.
This commit is contained in:
John Kessenich 2015-09-21 10:00:42 -06:00
commit ff4f04dd0e
2 changed files with 16 additions and 6 deletions
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17
SPIRV/SpvBuilder.cpp
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@ -2304,9 +2304,18 @@ Builder::Loop::Loop(Builder& builder, bool testFirstArg)
merge(new Block(builder.getUniqueId(), *function)), merge(new Block(builder.getUniqueId(), *function)),
body(new Block(builder.getUniqueId(), *function)), body(new Block(builder.getUniqueId(), *function)),
testFirst(testFirstArg), testFirst(testFirstArg),
isFirstIteration(testFirst isFirstIteration(nullptr)
? nullptr {
: new Instruction(builder.getUniqueId(), builder.makeBoolType(), OpPhi)) if (!testFirst)
{} {
// You may be tempted to rewrite this as
// new Instruction(builder.getUniqueId(), builder.makeBoolType(), OpPhi);
// This will cause subtle test failures because builder.getUniqueId(),
// and builder.makeBoolType() can then get run in a compiler-specific
// order making tests fail for certain configurations.
Id instructionId = builder.getUniqueId();
isFirstIteration = new Instruction(instructionId, builder.makeBoolType(), OpPhi);
}
}
}; // end spv namespace }; // end spv namespace

5
SPIRV/SpvBuilder.h
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@ -564,8 +564,9 @@ protected:
const bool testFirst; const bool testFirst;
// When the test executes after the body, this is defined as the phi // When the test executes after the body, this is defined as the phi
// instruction that tells us whether we are on the first iteration of // instruction that tells us whether we are on the first iteration of
// the loop. Otherwise this is null. // the loop. Otherwise this is null. This is non-const because
Instruction* const isFirstIteration; // it has to be initialized outside of the initializer-list.
Instruction* isFirstIteration;
}; };
// Our loop stack. // Our loop stack.