+ /* Compute a snapshot of current_function_uses_only_leaf_regs. Relying
+ on the final value of the flag means deferring the prologue/epilogue
+ expansion until just before the second scheduling pass, which is too
+ late to emit multiple epilogues or return insns.
+
+ Of course we are making the assumption that the value of the flag
+ will not change between now and its final value. Of the three parts
+ of the formula, only the last one can reasonably vary. Let's take a
+ closer look, after assuming that the first two ones are set to true
+ (otherwise the last value is effectively silenced).
+
+ If only_leaf_regs_used returns false, the global predicate will also
+ be false so the actual frame size calculated below will be positive.
+ As a consequence, the save_register_window insn will be emitted in
+ the instruction stream; now this insn explicitly references %fp
+ which is not a leaf register so only_leaf_regs_used will always
+ return false subsequently.
+
+ If only_leaf_regs_used returns true, we hope that the subsequent
+ optimization passes won't cause non-leaf registers to pop up. For
+ example, the regrename pass has special provisions to not rename to
+ non-leaf registers in a leaf function. */
+ sparc_leaf_function_p
+ = optimize > 0 && leaf_function_p () && only_leaf_regs_used ();