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Shader preprocessor: Fix for ASAN failure -- need to add SSE padding to substitution text generated for TEXT macros.

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#jira UE-202569
#rnx
#rb dan.elksnitis

[CL 30331769 by jason hoerner in ue5-main branch]
This commit is contained in:
jason hoerner
2023-12-14 16:35:09 -05:00
parent e3956a12ac
commit 903ff2eea7
2 changed files with 25 additions and 12 deletions
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19
Engine/Source/Developer/ShaderPreprocessor/Private/ShaderPreprocessor.cpp
View File

@@ -326,6 +326,19 @@ static void CopyStringToAnsiCharArray(const TCHAR* Text, int32 TextLen, TArray<A
*OutData = 0;
}
// Adds 16 bytes of zeroes at end, to allow SSE reads at the end of the buffer without reading past the end of the heap allocation
static void CopyStringToAnsiCharArraySSEPadded(const TCHAR* Text, int32 TextLen, TArray<ANSICHAR>& Out)
{
constexpr int32 SSEPadding = 16;
Out.SetNumUninitialized(TextLen + SSEPadding);
ANSICHAR* OutData = Out.GetData();
for (int32 CharIndex = 0; CharIndex < TextLen; CharIndex++, OutData++, Text++)
{
*OutData = (ANSICHAR)*Text;
}
FMemory::Memset(OutData, 0, SSEPadding * sizeof(ANSICHAR));
}
static const ANSICHAR* StbResolveInclude(const ANSICHAR* PathInSource, uint32 PathLen, const ANSICHAR* ParentPathAnsi, void* RawContext)
{
FStbPreprocessContext& Context = *reinterpret_cast<FStbPreprocessContext*>(RawContext);
@@ -533,11 +546,11 @@ static const char* StbCustomMacroBegin(const char* OriginalText, void* RawContex
Entry.Hash = CityHash32((const char*)Entry.SourceText.GetCharArray().GetData(), sizeof(FString::ElementType) * Entry.SourceText.Len());
Context.TextGlobalCount += Entry.ConvertedText.Len();
// Generate substitution string
// Generate substitution string -- need SSE padding on any text handled by the preprocessor
if (Entry.bIsAssert)
{
const FString HashString = FString::Printf(TEXT("%u"), Entry.Hash);
CopyStringToAnsiCharArray(*HashString, HashString.Len(), Context.TextMacroSubstituted);
CopyStringToAnsiCharArraySSEPadded(*HashString, HashString.Len(), Context.TextMacroSubstituted);
}
else
{
@@ -545,7 +558,7 @@ static const char* StbCustomMacroBegin(const char* OriginalText, void* RawContex
const FString InitHashEnd(TEXT(")"));
const FString HashText = InitHashBegin + FString::FromInt(EntryIndex) + InitHashEnd;
CopyStringToAnsiCharArray(*HashText, HashText.Len(), Context.TextMacroSubstituted);
CopyStringToAnsiCharArraySSEPadded(*HashText, HashText.Len(), Context.TextMacroSubstituted);
}
return Context.TextMacroSubstituted.GetData();

18
Engine/Source/Developer/ShaderPreprocessor/Private/stb_preprocess/preprocessor.h
View File

@@ -75,15 +75,15 @@ typedef void (*freefile_callback_func)(const char* filename, const char* loaded_
// note: returned resolved paths must remain valid for the lifetime of a single preprocessor execution
typedef const char* (*resolveinclude_callback_func)(const char* path, unsigned int path_len, const char* parent, void* custom_context);
// Callback functions for custom macros. Custom macros return their own substitution text, which is then further
// preprocessed. The text passed to the callback includes the macro identifier and its arguments, with backslashes
// removed. A function is called when entering the macro, and again when complete, allowing stateful logic
// based on whether parsing is inside a certain custom macro. Any custom macro will automatically be disabled
// inside itself, with the idea that this allows a singleton buffer for the substitution text, as there's no
// concern about nested calls. If text is dynamically allocated, the caller is responsible for freeing it. It's
// also valid to return the original text passed in as the substitution text, if you just want to set some state
// inside the context, and not actually change the macro text -- since the macro is disabled, it will then be
// echoed as non-macro text.
// Callback functions for custom macros. Custom macros return their own substitution text, which is then further preprocessed.
// The substitution text must include 15 bytes of padding past the null terminator, as the preprocessor uses SSE reads which may
// read past the null terminator. The text passed to the callback includes the macro identifier and its arguments, with backslashes
// removed. A function is called when entering the macro, and again when complete, allowing stateful logic based on whether
// parsing is inside a certain custom macro. Any custom macro will automatically be disabled inside itself, with the idea that
// this allows a singleton buffer for the substitution text, as there's no concern about nested calls. If text is dynamically
// allocated, the caller is responsible for freeing it. It's also valid to return the original text passed in as the substitution
// text, if you just want to set some state inside the context, and not actually change the macro text -- since the macro is
// disabled, it will then be echoed as non-macro text.
typedef const char* (*custommacro_begin_callback_func)(const char* original_text, void* custom_context);
typedef void (*custommacro_end_callback_func)(const char* original_text, void* custom_context, const char* substitution_text);