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

[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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weiguozhi wrote:

Longjmp modifies fp and sp, these instructions can be treated as destroying current stack frame and setting up stack frame for the jump target.

How about set FrameDestroy flag for these longjmp instructions, then spillFPBP can ignore these instructions.

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