[PATCH] D14948: [X86] Use precise CFI for pushes by default

[Michael Kuperstein via llvm-commits]

mkuper added a comment.

Thank Dave, Reid!

In http://reviews.llvm.org/D14948#296095, @rnk wrote:

> MachO compact unwind info can't support precise unwind info, though, right? Should this depend on the target?


Right. but it can't support the "less precise" version either, if there is more than one call in a function. So this doesn't control the MachO behavior.


================
Comment at: include/llvm/CodeGen/MachineModuleInfo.h:170
@@ +169,3 @@
+  /// information. False if we only need CFA to be precise at call sites.
+  bool UsePreciseUnwindInfo;
+
----------------
DavidKreitzer wrote:
> It might be a good idea to add the main points of our discussion to this comment:
> 
> - that synchronous (i.e. non-precise) unwind info should be enabled under some yet-to-be-defined switch
> - that we would first need the ability to simultaneously emit a synchronous .eh_frame and precise .debug_frame under that switch
> 
Yes, right, no point in deferring right until I actually add the switch.

================
Comment at: include/llvm/CodeGen/MachineModuleInfo.h:243
@@ -242,1 +242,3 @@
+  bool usePreciseUnwindInfo() const { return UsePreciseUnwindInfo; }
+  bool setUsePreciseUnwindInfo(bool b) { UsePreciseUnwindInfo = b; }
 
----------------
DavidKreitzer wrote:
> This should return void, right?
Argh, right, thanks!


http://reviews.llvm.org/D14948