[llvm] [AMDGPU][Uniformity][TTI] Make Uniformity Analysis Operand-Aware with Custom Target Hook (PR #137639)

[Jay Foad via llvm-commits]

================
@@ -785,6 +797,14 @@ void GenericUniformityAnalysisImpl<ContextT>::markDivergent(
     const InstructionT &I) {
   if (isAlwaysUniform(I))
     return;
+  // Check if instruction requires custom uniformity analysis
+  auto It = UniformInstruction.find(&I);
+  if (It != UniformInstruction.end()) {
+    if (It->second == InstructionUniformity::Custom && isCustomUniform(I)) {
+      addUniformOverride(I);
----------------
jayfoad wrote:

> I think to fix this, I should make this decision once divergence propagation is completed, or any other suggestion?

No, it must be done _during_ the divergence propagation, so that the divergence of the result can be propagated to other instructions.

https://github.com/llvm/llvm-project/pull/137639