[llvm] [X86] Don't save/restore fp around longjmp instructions (PR #102556)

[Reid Kleckner via llvm-commits]

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@@ -174,6 +175,9 @@ class X86MachineFunctionInfo : public MachineFunctionInfo {
   bool FPClobberedByCall = false;
   bool BPClobberedByCall = false;
 
+  // A set of instructions clobber FP generated from longjmp.
+  SmallSet<MachineInstr *, 2> LongJmpMIClobberFP;
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rnk wrote:

I like that approach, although there is some risk that the FrameDestroy flag is used to detect epilogue code. Longjmp instructions are effectively epilogue code: it tears down the frame and replaces it.

https://github.com/llvm/llvm-project/pull/102556