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| author | Eric Botcazou <ebotcazou@adacore.com> | 2022-10-29 10:16:18 +0200 |
|---|---|---|
| committer | Eric Botcazou <ebotcazou@adacore.com> | 2022-10-29 14:10:45 +0200 |
| commit | 96ba0c369ee86d61b6df2f8fb8364028a113acf7 (patch) | |
| tree | 40918ab8225545cac6614d7e2368ad399f8654e8 | |
| parent | 7e7ebe3e350fde90fe49ab41ce3b92a811bb6370 (diff) | |
| download | gcc-96ba0c369ee86d61b6df2f8fb8364028a113acf7.zip gcc-96ba0c369ee86d61b6df2f8fb8364028a113acf7.tar.gz gcc-96ba0c369ee86d61b6df2f8fb8364028a113acf7.tar.bz2 | |
Restore RTL alias analysis for hard frame pointer
The change:
2021-07-28 Bin Cheng <bin.cheng@linux.alibaba.com>
alias.c (init_alias_analysis): Don't skip prologue/epilogue.
broke the alias analysis for the hard frame pointer (when it is used as a
frame pointer, i.e. when the frame pointer is not eliminated) described in
the large comment at the top of the file, because static_reg_base_value is
set for it and, consequently, new_reg_base_value too.
When the instruction saving the stack pointer into the hard frame pointer in
the prologue is processed, it is viewed as a second set of the hard frame
pointer and to a different value by record_set, which then proceeds to reset
new_reg_base_value to 0 and the game is over.
gcc/
* alias.cc (init_alias_analysis): Do not record sets to the hard
frame pointer if the frame pointer has not been eliminated.
| -rw-r--r-- | gcc/alias.cc | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/gcc/alias.cc b/gcc/alias.cc index d54feb1..c62837d 100644 --- a/gcc/alias.cc +++ b/gcc/alias.cc @@ -3369,6 +3369,10 @@ memory_modified_in_insn_p (const_rtx mem, const_rtx insn) void init_alias_analysis (void) { + const bool frame_pointer_eliminated + = reload_completed + && !frame_pointer_needed + && targetm.can_eliminate (FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM); unsigned int maxreg = max_reg_num (); int changed, pass; int i; @@ -3446,12 +3450,8 @@ init_alias_analysis (void) for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (static_reg_base_value[i] /* Don't treat the hard frame pointer as special if we - eliminated the frame pointer to the stack pointer instead. */ - && !(i == HARD_FRAME_POINTER_REGNUM - && reload_completed - && !frame_pointer_needed - && targetm.can_eliminate (FRAME_POINTER_REGNUM, - STACK_POINTER_REGNUM))) + eliminated the frame pointer to the stack pointer. */ + && !(i == HARD_FRAME_POINTER_REGNUM && frame_pointer_eliminated)) { new_reg_base_value[i] = static_reg_base_value[i]; bitmap_set_bit (reg_seen, i); @@ -3467,10 +3467,15 @@ init_alias_analysis (void) { rtx note, set; + /* Treat the hard frame pointer as special unless we + eliminated the frame pointer to the stack pointer. */ + if (!frame_pointer_eliminated + && modified_in_p (hard_frame_pointer_rtx, insn)) + continue; + /* If this insn has a noalias note, process it, Otherwise, scan for sets. A simple set will have no side effects which could change the base value of any other register. */ - if (GET_CODE (PATTERN (insn)) == SET && REG_NOTES (insn) != 0 && find_reg_note (insn, REG_NOALIAS, NULL_RTX)) |