On 11/29/2016 04:10 AM, Wilco Dijkstra wrote:
GCC caches the whether a function is a leaf in crtl->is_leaf. Using this in the backend is best as leaf_function_p may not work correctly (eg. while emitting prolog or epilog code). There are many reads of crtl->is_leaf before it is initialized. Many targets do in targetm.frame_pointer_required (eg. arm, aarch64, i386, mips, sparc), which is called before register allocation by ira_setup_eliminable_regset and sched_init.Additionally, SHRINK_WRAPPING_ENABLED calls targetm.have_simple_return, which evaluates the condition of the simple_return instruction. On ARM this results in a call to use_simple_return_p which requires crtl->is_leaf to be set correctly. To fix this, initialize crtl->is_leaf in ira_setup_eliminable_regset and early on in ira. A bootstrap did not find any uninitialized reads of crtl->is_leaf on Thumb-2. A follow-up patch will remove incorrect uses of leaf_function_p from the ARM backend. Bootstrap OK (verified all reads of is_leaf in ARM backend are now after initialization), OK for commit? ChangeLog: 2016-11-29 Wilco Dijkstra <wdijk...@arm.com> * gcc/ira.c (ira_setup_eliminable_regset): Initialize crtl->is_leaf. (ira): Move initialization of crtl->is_leaf earlier.
OK. jeff
