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

[Matt Arsenault via llvm-commits]

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@@ -460,6 +519,16 @@ bool SIModeRegister::run(MachineFunction &MF) {
   const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
   const SIInstrInfo *TII = ST.getInstrInfo();
 
+  // The mixed case is not handled: a restore would undo the program's request.
+  auto AnyInstr = [&MF](function_ref<bool(const MachineInstr &)> P) {
+    return any_of(
+        MF, [&P](const MachineBasicBlock &MBB) { return any_of(MBB, P); });
+  };
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arsenm wrote:

Shouldn't introduce new walks over the function or blocks

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