On 08/29/2016 03:31 AM, Bernd Schmidt wrote:
On 08/01/2016 03:42 AM, Segher Boessenkool wrote:
+@deftypefn {Target Hook} void
TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+Emit prologue insns for the components indicated by the parameter.
+@end deftypefn
+
+@deftypefn {Target Hook} void
TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+Emit epilogue insns for the components indicated by the parameter.
+@end deftypefn
How do these actually know where to save/restore registers? The frame
pointer may have been eliminated, and SP isn't necessarily constant
during the function. Seems like you'd have to calculate CFA reg/offset
much like dwarf2out does and pass it to this hook.
So I think the confusion here is these hooks are independent of
placement. ie, the target independent code does something like:
FOR_EACH_BB
Build the component bitmap using the incoming edge components
Emit the prologue components at the start of the block
Emit the epilogue components at the end of the block
The components handled by a particular block start are set/cleared by
the other hooks.
jeff
