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Fix PAQ memory leak by never pushing redundant stages to backing vector #7442

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Fix PAQ memory leak by never pushing redundant stages to backing vector #7442

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14 changes: 12 additions & 2 deletions tools/clang/lib/Parse/ParseDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -397,9 +397,19 @@ bool Parser::MaybeParseHLSLAttributes(std::vector<hlsl::UnusualAnnotation *> &ta
stage = hlsl::DXIL::PayloadAccessShaderStage::Miss;
} else if (shaderStage == "anyhit") {
stage = hlsl::DXIL::PayloadAccessShaderStage::Anyhit;
}
}

// mod.ShaderStages can only take four elements before it starts to
// migrate. Make sure not to add redundant stages.
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we could exit the while loop early here if mod.size() is 4?

Comment on lines +402 to +403
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If the problem is that we leak memory if the ShaderStages SmallVector ever grows, then wouldn't a better fix be to avoid a SmallVector (or any type that can move its memory) entirely? That is, should we adjust PayloadAccessAnnotation to store the stages in a fixed data structure instead?

bool IsDuplicate = false;
for (auto s : mod.ShaderStages)
if (s == stage) {
IsDuplicate = true;
break;
}
if (!IsDuplicate)
mod.ShaderStages.push_back(stage);

mod.ShaderStages.push_back(stage);
ConsumeToken(); // consume shader type

if (Tok.is(tok::comma)) // check if we have a list of shader types
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21 changes: 21 additions & 0 deletions tools/clang/test/HLSLFileCheck/hlsl/payload_qualifier/redundant_clause.hlsl
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@@ -0,0 +1,21 @@
// RUN: %dxc -T lib_6_9 %s

// COM: No FileCheck required: Error raised by ASAN-enabled DXC builds where underlying bug #7104 is not fixed.
// COM: This checks that the backing memory of the shader stages vector does not migrate when more than four (it's preallocated size) shader stages are added.

struct [raypayload] Payload
{
int a : read(anyhit,caller,miss,closesthit,closesthit) : write(anyhit,caller,miss,closesthit,caller);
};

struct Attribs
{
float2 barys;
};

[shader("closesthit")]
void ClosestHitInOut( inout Payload payload, in Attribs attribs )
{
if (payload.a == 1)
payload.a = 2;
}