[llvm] [DirectX] Set whole-module flags prior to evaluating per-function flags (PR #139967)

[Justin Bogner via llvm-commits]

================
@@ -207,26 +207,69 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
   }
 }
 
-/// Construct ModuleShaderFlags for module Module M
-void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
-                                   DXILResourceMap &DRM,
-                                   const ModuleMetadataInfo &MMDI) {
+/// Set shader flags that apply to all functions within the module
+void ModuleShaderFlags::gatherGlobalModuleFlags(
+    ComputedShaderFlags &CSF, const Module &M, const DXILResourceMap &DRM,
+    const ModuleMetadataInfo &MMDI) {
 
-  CanSetResMayNotAlias = MMDI.DXILVersion >= VersionTuple(1, 7);
-  // The command line option -res-may-alias will set the dx.resmayalias module
-  // flag to 1, thereby disabling the ability to set the ResMayNotAlias flag
-  if (auto *ResMayAlias = mdconst::extract_or_null<ConstantInt>(
-          M.getModuleFlag("dx.resmayalias")))
-    CanSetResMayNotAlias = !ResMayAlias->getValue().getBoolValue();
+  // Set DisableOptimizations flag based on the presence of OptimizeNone
+  // attribute of entry functions.
+  if (MMDI.EntryPropertyVec.size() > 0) {
+    CSF.DisableOptimizations = MMDI.EntryPropertyVec[0].Entry->hasFnAttribute(
+        llvm::Attribute::OptimizeNone);
+    // Ensure all entry functions have the same optimization attribute
+    for (const auto &EntryFunProps : MMDI.EntryPropertyVec)
+      if (CSF.DisableOptimizations !=
+          EntryFunProps.Entry->hasFnAttribute(llvm::Attribute::OptimizeNone))
+        EntryFunProps.Entry->getContext().diagnose(DiagnosticInfoUnsupported(
+            *(EntryFunProps.Entry), "Inconsistent optnone attribute "));
+  }
+
+  CSF.UAVsAtEveryStage = hasUAVsAtEveryStage(DRM, MMDI);
 
+  // Set the Max64UAVs flag if the number of UAVs is > 8
+  uint32_t NumUAVs = 0;
+  for (auto &UAV : DRM.uavs())
+    if (MMDI.ValidatorVersion < VersionTuple(1, 6))
+      NumUAVs++;
+    else // MMDI.ValidatorVersion >= VersionTuple(1, 6)
+      NumUAVs += UAV.getBinding().Size;
+  if (NumUAVs > 8)
+    CSF.Max64UAVs = true;
+
+  // Set the module flag that enables native low-precision execution mode.
   // NativeLowPrecisionMode can only be set when the command line option
   // -enable-16bit-types is provided. This is indicated by the dx.nativelowprec
   // module flag being set
-  CanSetNativeLowPrecisionMode = false;
+  // This flag is needed even if the module does not use 16-bit types because a
+  // corresponding debug module may include 16-bit types, and tools that use the
+  // debug module may expect it to have the same flags as the original
   if (auto *NativeLowPrec = mdconst::extract_or_null<ConstantInt>(
           M.getModuleFlag("dx.nativelowprec")))
     if (MMDI.ShaderModelVersion >= VersionTuple(6, 2))
-      CanSetNativeLowPrecisionMode = NativeLowPrec->getValue().getBoolValue();
+      CSF.NativeLowPrecisionMode = NativeLowPrec->getValue().getBoolValue();
+
+  CanSetResMayNotAlias = MMDI.DXILVersion >= VersionTuple(1, 7);
+  // The command line option -res-may-alias will set the dx.resmayalias module
+  // flag to 1, thereby disabling the ability to set the ResMayNotAlias flag
+  if (auto *ResMayAlias = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("dx.resmayalias")))
+    if (ResMayAlias->getValue().getBoolValue())
+      CanSetResMayNotAlias = false;
----------------
bogner wrote:

Computing and setting this member variable inside the function like this is a bit of a surprising side effect. I think we should hoist the calculation of `CanSetResMayNotAlias` to its own thing and do it explicitly in `ModuleShaderFlags::initialize`

https://github.com/llvm/llvm-project/pull/139967