From acea40ac746971daf5b9e6091b908653407b86ea Mon Sep 17 00:00:00 2001 From: Wilco Dijkstra Date: Tue, 24 Oct 2017 16:58:02 +0000 Subject: [PATCH] PR60580: Fix frame pointer option magic To fix PR60580 simplify the logic in aarch64_override_options_after_change_1 (). If the frame pointer is enabled, set it to a special value that behaves similar to frame pointer omission. If we don't do this all leaf functions will get a frame pointer even if flag_omit_leaf_frame_pointer is set. If flag_omit_frame_pointer has this special value, we must force the frame pointer if not in a leaf function. We also need to force it in a leaf function if flag_omit_frame_pointer is not set or if LR is used. Doing this allows both -fomit-frame-pointer and -fomit-leaf-frame-pointer to be independently set and changed in each function with the expected behaviour. gcc/ PR middle-end/60580 * config/aarch64/aarch64.c (aarch64_frame_pointer_required) Check special value of flag_omit_frame_pointer. (aarch64_can_eliminate): Likewise. (aarch64_override_options_after_change_1): Simplify handling of -fomit-frame-pointer and -fomit-leaf-frame-pointer. From-SVN: r254052 --- gcc/ChangeLog | 9 +++++++++ gcc/config/aarch64/aarch64.c | 42 ++++++++++++++++++------------------------ 2 files changed, 27 insertions(+), 24 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 63bb64f..259dc01 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2017-10-24 Wilco Dijkstra + + PR middle-end/60580 + * config/aarch64/aarch64.c (aarch64_frame_pointer_required) + Check special value of flag_omit_frame_pointer. + (aarch64_can_eliminate): Likewise. + (aarch64_override_options_after_change_1): Simplify handling of + -fomit-frame-pointer and -fomit-leaf-frame-pointer. + 2017-10-24 Richard Biener PR tree-optimization/82697 diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index ed30b8c..d1aaf19 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -2867,12 +2867,13 @@ aarch64_output_probe_stack_range (rtx reg1, rtx reg2) static bool aarch64_frame_pointer_required (void) { - /* In aarch64_override_options_after_change - flag_omit_leaf_frame_pointer turns off the frame pointer by - default. Turn it back on now if we've not got a leaf - function. */ - if (flag_omit_leaf_frame_pointer - && (!crtl->is_leaf || df_regs_ever_live_p (LR_REGNUM))) + /* Use the frame pointer if enabled and it is not a leaf function, unless + leaf frame pointer omission is disabled. If the frame pointer is enabled, + force the frame pointer in leaf functions which use LR. */ + if (flag_omit_frame_pointer == 2 + && !(flag_omit_leaf_frame_pointer + && crtl->is_leaf + && !df_regs_ever_live_p (LR_REGNUM))) return true; /* Force a frame pointer for EH returns so the return address is at FP+8. */ @@ -5926,6 +5927,7 @@ aarch64_can_eliminate (const int from, const int to) LR in the function, then we'll want a frame pointer after all, so prevent this elimination to ensure a frame pointer is used. */ if (to == STACK_POINTER_REGNUM + && flag_omit_frame_pointer == 2 && flag_omit_leaf_frame_pointer && df_regs_ever_live_p (LR_REGNUM)) return false; @@ -8965,24 +8967,16 @@ aarch64_parse_override_string (const char* input_string, static void aarch64_override_options_after_change_1 (struct gcc_options *opts) { - /* The logic here is that if we are disabling all frame pointer generation - then we do not need to disable leaf frame pointer generation as a - separate operation. But if we are *only* disabling leaf frame pointer - generation then we set flag_omit_frame_pointer to true, but in - aarch64_frame_pointer_required we return false only for leaf functions. - - PR 70044: We have to be careful about being called multiple times for the - same function. Once we have decided to set flag_omit_frame_pointer just - so that we can omit leaf frame pointers, we must then not interpret a - second call as meaning that all frame pointer generation should be - omitted. We do this by setting flag_omit_frame_pointer to a special, - non-zero value. */ - if (opts->x_flag_omit_frame_pointer == 2) - opts->x_flag_omit_frame_pointer = 0; - - if (opts->x_flag_omit_frame_pointer) - opts->x_flag_omit_leaf_frame_pointer = false; - else if (opts->x_flag_omit_leaf_frame_pointer) + /* PR 70044: We have to be careful about being called multiple times for the + same function. This means all changes should be repeatable. */ + + /* If the frame pointer is enabled, set it to a special value that behaves + similar to frame pointer omission. If we don't do this all leaf functions + will get a frame pointer even if flag_omit_leaf_frame_pointer is set. + If flag_omit_frame_pointer has this special value, we must force the + frame pointer if not in a leaf function. We also need to force it in a + leaf function if flag_omit_frame_pointer is not set or if LR is used. */ + if (opts->x_flag_omit_frame_pointer == 0) opts->x_flag_omit_frame_pointer = 2; /* If not optimizing for size, set the default -- 2.7.4