[clang][HLSL][SPRI-V] Add convergence intrinsics (#80680)

HLSL has wave operations and other kind of function which required the
control flow to either be converged, or respect certain constraints as
where and how to re-converge.

At the HLSL level, the convergence are mostly obvious: the control flow
is expected to re-converge at the end of a scope.
Once translated to IR, HLSL scopes disapear. This means we need a way to
communicate convergence restrictions down to the backend.

For this, the SPIR-V backend uses convergence intrinsics. So this commit
adds some code to generate convergence intrinsics when required.

---------

Signed-off-by: Nathan Gauër <brioche@google.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index fb00782..a5fe396 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -5715,6 +5715,9 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   if (!CI->getType()->isVoidTy())
     CI->setName("call");
 
+  if (getTarget().getTriple().isSPIRVLogical() && CI->isConvergent())
+    CI = addControlledConvergenceToken(CI);
+
   // Update largest vector width from the return type.
   LargestVectorWidth =
       std::max(LargestVectorWidth, getMaxVectorWidth(CI->getType()));