[llvm] [AMDGPU] Restore the default rounding mode before calls and returns (PR #222247)

[Arseniy Obolenskiy via llvm-commits]

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@@ -432,6 +500,20 @@ void SIModeRegister::processBlockPhase3(MachineBasicBlock &MBB,
     else
       insertSetreg(MBB, &MBB.instr_front(), TII, Delta);
   }
+
+  // Restore the default at the sites recorded in Phase 1.
+  if (!enforceCallBoundary())
+    return;
+  for (auto &[MI, ChangeAtSite] : BlockInfo[ThisBlock]->BoundarySites) {
+    Status AtSite = BlockInfo[ThisBlock]->Pred.merge(ChangeAtSite);
+    if (AtSite.isCompatible(DefaultStatus))
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aobolensk wrote:

Yes, it has to be. This pass only sees one function at a time, so it cannot check what mode the call site or callee actually needs



https://github.com/llvm/llvm-project/pull/222247