Fix `SLANG_ENABLE_ASAN` CMake option #9108

ncelikNV · 2025-11-24T13:08:04Z

Fixes sanitizers silently not being enabled due to broken checks for
compiler support of sanitizer flags.

Fixes non-leak errors reported by ASan when running slang-test -api cpu on Linux.

Fixes #9097.
Fixes #9098.

…producible example for)

Clang was taking around 10 minutes to compile `slang-embedded-core-module-source.cpp` with optimizations. Disabling optimizations for these functions reduced the compilation time to about 12 seconds on my machine (Intel Core Ultra 7 165H), and had no noticeable impact on run-time performance. Run-time performance with optimizations: ``` $ hyperfine --shell=none './build/generators/Release/bin/slang-bootstrap -archive-type riff-lz4 -save-core-module-bin-source slang-core-module-generated.h -save-glsl-module-bin-source slang-glsl-module-generated.h' Benchmark 1: ./build/generators/Release/bin/slang-bootstrap -archive-type riff-lz4 -save-core-module-bin-source slang-core-module-generated.h -save-glsl-module-bin-source slang-glsl-module-generated.h Time (mean ± σ): 2.545 s ± 0.035 s [User: 2.333 s, System: 0.210 s] Range (min … max): 2.496 s … 2.620 s 10 runs ``` Run-time performance without optimizations: ``` $ hyperfine --shell=none './build/generators/Release/bin/slang-bootstrap -archive-type riff-lz4 -save-core-module-bin-source slang-core-module-generated.h -save-glsl-module-bin-source slang-glsl-module-generated.h' Benchmark 1: ./build/generators/Release/bin/slang-bootstrap -archive-type riff-lz4 -save-core-module-bin-source slang-core-module-generated.h -save-glsl-module-bin-source slang-glsl-module-generated.h Time (mean ± σ): 2.564 s ± 0.039 s [User: 2.350 s, System: 0.213 s] Range (min … max): 2.512 s … 2.614 s 10 runs ``` Disabling optimizations also makes `slang-embedded-core-module-source.cpp.o` slightly smaller: - 7.84 MiB with optimizations, - 7.37 MiB without optimizations. Fixes shader-slang#9054.

… result still unsigned"

…an-1

slangbot · 2025-11-24T13:15:19Z

⚠️ Serialization Code Changed

This PR modifies source/slang/slang-serialize-ir.cpp. Please review if you need to update:

kSupportedSerializationVersion: Should be incremented if you're making backwards-incompatible changes to the serialization format

This version number helps maintain compatibility when loading serialized IR modules.

ncelikNV · 2025-11-24T13:52:38Z

cmake/CompilerFlags.cmake

+            target_compile_options(${target} PRIVATE /fsanitize=address)
+            target_link_options(${target} PRIVATE /INCREMENTAL:NO)
+        else()
+            message(FATAL_ERROR "SLANG_ENABLE_ASAN: unsupported C++ compiler")


I thought it would be better to raise a FATAL_ERROR (which stops CMake generation) as users might not notice a warning. Since SLANG_ENABLE_ASAN defaults to OFF I think it's safe to assume that it being ON implies the user really doesn't want Slang being built without sanitizers.

ncelikNV · 2025-11-24T14:17:43Z

source/compiler-core/slang-gcc-compiler-util.cpp

+    if (PlatformUtil::isFamily(PlatformFamily::Unix, platformKind))
+    {
+        // Position independent
+        cmdLine.addArg("-fPIC");
+    }


Initial discussion: https://github.com/shader-slang/slang/pull/8980/files#r2528348258.

GCC used to emit the following warning when using -fPIC on Windows until GCC 6.1 (released in 2016):

-fPIC ignored for target (all code is position independent)

See gcc-mirror/gcc@0a1d992. I assume that's why this was restricted to PlatformFamily::Unix. The commit that added this restriction is from 2019 (~3 years after GCC 6.1's release): ea20066.

ncelikNV · 2025-11-24T14:39:24Z

source/compiler-core/slang-gcc-compiler-util.cpp


-    diagnostics->reset();
-    diagnostics->setRaw(SliceUtil::asCharSlice(exeRes.standardError));
+    diagnostics->appendRaw(SliceUtil::asCharSlice(exeRes.standardError));


Since CommandLineDownstreamCompiler::compile now splits compilation and linking into two commands, we need to be able to combine multiple commands' output into the same diagnostics object. Note that parseOutput is only ever called on a newly created diagnostics object (even without this PR's changes), so there was no need to call diagnostics->reset() here.

ncelikNV · 2025-11-24T14:40:14Z

source/core/slang-string.h

-    char* getData() const { return m_buffer ? m_buffer->getData() : (char*)""; }
+    char* getData() const
+    {
+        static char empty[] = "";
+        return m_buffer ? m_buffer->getData() : empty;
+    }


Initial discussion: https://github.com/shader-slang/slang/pull/8980/files#r2518762552.

ncelikNV · 2025-11-24T14:41:04Z

source/core/slang-string.h

-    bool operator==(const char* strbuffer) const { return (strcmp(begin(), strbuffer) == 0); }
+    bool operator==(const char* strbuffer) const
+    {
+        const char* volatile b = begin();
+        return (strcmp(b, strbuffer) == 0);
+    }


Initial discussion: https://github.com/shader-slang/slang/pull/8980/files#r2518778200.

ncelikNV · 2025-11-24T14:41:29Z

source/slang/slang-serialize-ast.cpp

-        Fossil::SerialWriter writer(blobBuilder);
        ASTSerialWriteContext context(moduleDecl, sourceLocWriter);
+        Fossil::SerialWriter writer(blobBuilder);


Fixes ASan error: stack-use-after-scope.

ncelikNV · 2025-11-24T14:42:01Z

tools/slang-fiddle/slang-fiddle-main.cpp

-    ComPtr<ISlangWriter> writer(new FileWriter(stderr, WriterFlag::AutoFlush));
+    ComPtr<ISlangWriter> writer(
+        new FileWriter(stderr, WriterFlag::IsUnowned | WriterFlag::AutoFlush));


stderr was being closed when exiting main, which meant sanitizers would fail to print diagnostics.

ncelikNV · 2025-11-24T14:42:21Z

tools/slang-unit-test/unit-test-com-host-callable.cpp

            const SlangPassThrough cppCompilers[] = {
                SLANG_PASS_THROUGH_VISUAL_STUDIO,
-                SLANG_PASS_THROUGH_GCC,
+#if SLANG_CLANG
                SLANG_PASS_THROUGH_CLANG,
+#else
+                SLANG_PASS_THROUGH_GCC,
+#endif


The issue here was that I was building Slang with Clang but a test was being built with GCC and the sanitizer runtime of one is incompatible with the other's. Maybe this code should just be edited to only test the compiler that is being used to build Slang instead of MSVC + either Clang or GCC, this was more of a quick fix.

ncelikNV · 2025-11-24T17:47:58Z

source/core/slang-zip-file-system.cpp

-        return UnownedStringSlice();
+        return String();
    }

-    return UnownedStringSlice(fileStat.m_filename).trim('/');
+    return String(UnownedStringSlice(fileStat.m_filename).trim('/'));


Fixes ASan error: stack-use-after-return.

Fixes sanitizers silently not being enabled due to broken checks for compiler support of sanitizer flags. Fixes non-leak errors reported by ASan when running `slang-test -api cpu` on Linux. Fixes shader-slang#9097. Fixes shader-slang#9098.

…pported

ncelikNV · 2025-11-25T15:54:51Z

tools/slang-unit-test/unit-test-get-target-code.cpp

+    SLANG_CHECK_ABORT(code != nullptr);

-    SLANG_CHECK(code->getBufferSize() != 0);
+    SLANG_CHECK_ABORT(code->getBufferSize() != 0);


Fixes crash/segfault due to null pointer dereference if libslang-glslang-<version>.so couldn't be found (build/<config>/lib not in LD_LIBRARY_PATH): code would be nullptr.

ncelikNV · 2025-11-25T16:44:58Z

tools/slang-unit-test/unit-test-separate-debug.cpp

-    SLANG_CHECK(compileResult->getMetadata(metadata.writeRef()) == SLANG_OK);
+    SLANG_CHECK_ABORT(result == SLANG_OK);
+    SLANG_CHECK_ABORT(compileResult != nullptr);
+    SLANG_CHECK_ABORT(compileResult->getItemCount() == 2);


Fixes crash/segfault due to null pointer dereference if libslang-glslang-<version>.so couldn't be found (build/<config>/lib not in LD_LIBRARY_PATH): result would be != SLANG_OK and compileResult would be nullptr.

ncelikNV added 20 commits November 11, 2025 20:29

Fix SLANG_ENABLE_ASAN CMake option

8922141

Fixes shader-slang#8646.

Fix formatting

4dae658

Fix GCC -Wstring-compare warning (which I couldn't write a minimal re…

7e8a478

…producible example for)

Fix MSVC warning

53b5d33

Maybe fix macOS ld error

ffd7a0e

Remove own TODO/NOTE comments

9fe3e02

Fix Clang unused variable warning

506d457

Fix MSVC warning

817f6db

Revert #if 0 cleanups

0a30070

Re-enable SLANG_UNALIGNED_ACCESS and fix slang-byte-encode-util.cpp UB

3d46bc2

Fix logical right shift being used instead of arithmetic right shift

d688ef3

Fix UIntSet::clear() call sites instead of adding non-null buffer check

bc306b7

Merge branch 'master' into fix-slang-enable-asan

fa1982c

Fix CommandLineDownstreamCompiler::compile()

39971df

Fix MSVC shadowing warning

b4a3193

Silence MSVC warning: "unary minus operator applied to unsigned type,…

5464944

… result still unsigned"

Document that these functions are only called once

6076e54

Merge branch 'fix-slang-enable-asan' into fix-slang-enable-asan-1

1d870d6

Merge branch 'fix-clang-release-build-times' into fix-slang-enable-as…

799a19a

…an-1

ncelikNV added the pr: non-breaking PRs without breaking changes label Nov 24, 2025

ncelikNV commented Nov 24, 2025

View reviewed changes

ncelikNV mentioned this pull request Nov 24, 2025

Fix SLANG_ENABLE_ASAN CMake option #8980

Closed

ncelikNV added 3 commits November 25, 2025 17:37

Fix SLANG_ENABLE_ASAN CMake option

03c725f

Fixes sanitizers silently not being enabled due to broken checks for compiler support of sanitizer flags. Fixes non-leak errors reported by ASan when running `slang-test -api cpu` on Linux. Fixes shader-slang#9097. Fixes shader-slang#9098.

Minor refactorings

f3630e2

Emit CMake FATAL_ERROR instead of warning if the C++ compiler is unsu…

d33b400

…pported

ncelikNV force-pushed the fix-slang-enable-asan-1 branch from 1cbaf81 to d33b400 Compare November 25, 2025 15:38

ncelikNV commented Nov 25, 2025

View reviewed changes

Fix SLANG_ENABLE_ASAN CMake option #9108

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Fix `SLANG_ENABLE_ASAN` CMake option #9108

Fix `SLANG_ENABLE_ASAN` CMake option #9108

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