Fix warnings for gcc 12.3 (#3286)

* Silence a few gcc out of bounds warnings

* Search upwards from executable for prelude directory instead of assuming depth

* comment wording

* Check return values of read and write

* Correct path to vulkan headers in gfx

* Correct diagnostic on missing file in slang-embed

* Do not use absolute path to libraries in test-context.cpp

---------

Co-authored-by: Yong He <yonghe@outlook.com>

6 files changed, 21 insertions, 8 deletions

diff --git a/source/core/slang-blob.h b/source/core/slang-blob.h
index 7a2c4d967..e678680aa 100644
--- a/source/core/slang-blob.h
+++ b/source/core/slang-blob.h
@@ -129,6 +129,7 @@ public:
         /// Allocate size including a 0 byte at `size`.
     void* allocateTerminated(size_t size)
     {
+        SLANG_ASSUME(size != std::numeric_limits<size_t>::max());
         uint8_t* data = (uint8_t*)allocate(size + 1);
         data[size] = 0;
         m_sizeInBytes = size;
diff --git a/source/core/slang-io.cpp b/source/core/slang-io.cpp
index 8a2243b15..4ef5ecc2d 100644
--- a/source/core/slang-io.cpp
+++ b/source/core/slang-io.cpp
@@ -126,7 +126,8 @@ namespace Slang
         List<char> buffer;
         auto copySize = builder.getLength();
         buffer.setCount(copySize + 1);
-        SLANG_ASSERT(copySize < PTRDIFF_MAX); // Shhh gcc, it's ok, we're not copying 9000 Petabytes
+        // Satisfy GCC
+        SLANG_ASSUME(copySize < PTRDIFF_MAX && copySize > 0);
         ::memcpy(buffer.getBuffer(), builder.getBuffer(), copySize);
         buffer[copySize] = 0;
 
diff --git a/source/core/slang-test-tool-util.cpp b/source/core/slang-test-tool-util.cpp
index 68673a29f..487ea89ac 100644
--- a/source/core/slang-test-tool-util.cpp
+++ b/source/core/slang-test-tool-util.cpp
@@ -103,12 +103,21 @@ static SlangResult _addCUDAPrelude(const String& rootPath, slang::IGlobalSession
     String parentPath;
     SLANG_RETURN_ON_FAIL(getExeDirectoryPath(inExePath, parentPath));
 
-    // From directory to the root is ../../.. 
-    // Work out the relative path to the root
-    String rootRelPath = Path::combine(parentPath, "../../../");
+    // Work out the relative path to the root, we will search upwards until we
+    // find a directory containing 'prelude/slang-cpp-prelude.h'
+    String rootRelPath;
+    SLANG_RETURN_ON_FAIL(Path::getCanonical(parentPath, rootRelPath));
+    do
+    {
+        if(File::exists(Path::combine(rootRelPath, "prelude/slang-cpp-prelude.h")))
+            break;
+
+        rootRelPath = Path::getParentDirectory(rootRelPath);
+        if(rootRelPath == "")
+            return SLANG_E_NOT_AVAILABLE;
+    } while(1);
 
-    // We want the absolute path to the root
-    SLANG_RETURN_ON_FAIL(Path::getCanonical(rootRelPath, outExePath));
+    outExePath = std::move(rootRelPath);
     return SLANG_OK;
 }
 
diff --git a/source/core/slang-test-tool-util.h b/source/core/slang-test-tool-util.h
index 186003a62..1e56500d2 100644
--- a/source/core/slang-test-tool-util.h
+++ b/source/core/slang-test-tool-util.h
@@ -53,7 +53,7 @@ struct TestToolUtil
         /// Given the exePath, give return the absolute path to the directory the exe is in
     static SlangResult getExeDirectoryPath(const char* exePath, String& outExeDirectoryPath);
 
-        /// Sets the default preludes on the session based on the executable path
+        /// Sets the default preludes on the session based on an explicit path
     static SlangResult setSessionDefaultPreludeFromRootPath(const String& rootPath, slang::IGlobalSession* session);
 
         /// Calculates the path that is the combination of parentPath, and relPath
diff --git a/source/core/unix/slang-unix-process.cpp b/source/core/unix/slang-unix-process.cpp
index 3ab113d83..ee5484fd8 100644
--- a/source/core/unix/slang-unix-process.cpp
+++ b/source/core/unix/slang-unix-process.cpp
@@ -516,7 +516,8 @@ static int pipeCLOEXEC(int pipefd[2])
 
         // Signal the failure to our parent
         int execErr = errno;
-        ::write(execWatchPipe[1], &execErr, sizeof(execErr));
+        if(::write(execWatchPipe[1], &execErr, sizeof(execErr)))
+            fprintf(stderr, "error: `exec` watch pipe write failed\n");
 
         // NOTE! Because we have dup2 into STDERR_FILENO, this error will *not* generally appear on
         // the terminal but in the stderrPipe. 
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 3274c3223..0eae87a10 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -323,6 +323,7 @@ struct SpvLiteralBits
         char* dst = (char*)(result.value.getBuffer());
 
         // Copy the text
+        SLANG_ASSUME(textCount >= 0);
         memcpy(dst, text.begin(), textCount);
 
         // Set terminating 0, and remaining buffer 0s