From 2daad50b025d4db0492cf14390ba76272f2df015 Mon Sep 17 00:00:00 2001 From: Claudiu Zissulescu Date: Thu, 1 Jun 2017 11:42:49 +0200 Subject: [PATCH] [ARC] Prevent moving stores to the frame before the stack adjustment. If the stack pointer is needed, emit a special barrier that will prevent the scheduler from moving stores to the frame before the stack adjustment. For example: [snip] mov_s fp,sp ; frame pointer is set here [snip] st r1,[fp,-24] ; frame pointer is used here [snip] sub_s sp,sp,0x20 ; stack pointer adjusted So we can easily see that any interrupt between the `st` and `sub` instruction will lead to faulty code as the interrupt routine will use a faulty sp register, and, potentially, overwriting the value stored by 'st' instruction. Thus, adding a scheduler barrier will force the compiler to emit the `sub` instruction before the store one. 2017-06-01 Claudiu Zissulescu * config/arc/arc.c (arc_expand_prologue): Emit a special barrier to prevent store reordering. * config/arc/arc.md (UNSPEC_ARC_STKTIE): Define. (type): Add block type. (stack_tie): Define special instruction to be used in expand_prologue. From-SVN: r248781 --- gcc/ChangeLog | 9 +++++++++ gcc/config/arc/arc.c | 10 +++++++++- gcc/config/arc/arc.md | 15 ++++++++++++++- 3 files changed, 32 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 867947a88dd..92a7c0ab6bc 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2017-06-01 Claudiu Zissulescu + + * config/arc/arc.c (arc_expand_prologue): Emit a special barrier + to prevent store reordering. + * config/arc/arc.md (UNSPEC_ARC_STKTIE): Define. + (type): Add block type. + (stack_tie): Define special instruction to be used in + expand_prologue. + 2017-06-01 Claudiu Zissulescu * config/arc/arc.md (commutative_binary_comparison): Remove 'I' diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c index a45e12bc7d3..caf01c8b6e1 100644 --- a/gcc/config/arc/arc.c +++ b/gcc/config/arc/arc.c @@ -2968,7 +2968,15 @@ arc_expand_prologue (void) frame_size_to_allocate -= first_offset; /* Allocate the stack frame. */ if (frame_size_to_allocate > 0) - frame_stack_add ((HOST_WIDE_INT) 0 - frame_size_to_allocate); + { + frame_stack_add ((HOST_WIDE_INT) 0 - frame_size_to_allocate); + /* If the frame pointer is needed, emit a special barrier that + will prevent the scheduler from moving stores to the frame + before the stack adjustment. */ + if (arc_frame_pointer_needed ()) + emit_insn (gen_stack_tie (stack_pointer_rtx, + hard_frame_pointer_rtx)); + } /* Setup the gp register, if needed. */ if (crtl->uses_pic_offset_table) diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md index b53ec02f662..501413854dd 100644 --- a/gcc/config/arc/arc.md +++ b/gcc/config/arc/arc.md @@ -135,6 +135,7 @@ UNSPEC_ARC_VMAC2HU UNSPEC_ARC_VMPY2H UNSPEC_ARC_VMPY2HU + UNSPEC_ARC_STKTIE ]) (define_c_enum "vunspec" [ @@ -205,7 +206,7 @@ simd_vcompare, simd_vpermute, simd_vpack, simd_vpack_with_acc, simd_valign, simd_valign_with_acc, simd_vcontrol, simd_vspecial_3cycle, simd_vspecial_4cycle, simd_dma, mul16_em, div_rem, - fpu" + fpu, block" (cond [(eq_attr "is_sfunc" "yes") (cond [(match_test "!TARGET_LONG_CALLS_SET && (!TARGET_MEDIUM_CALLS || GET_CODE (PATTERN (insn)) != COND_EXEC)") (const_string "call") (match_test "flag_pic") (const_string "sfunc")] @@ -6606,6 +6607,18 @@ (set_attr "predicable" "yes,no,no,yes,no") (set_attr "cond" "canuse,nocond,nocond,canuse_limm,nocond")]) +(define_insn "stack_tie" + [(set (mem:BLK (scratch)) + (unspec:BLK [(match_operand:SI 0 "register_operand" "rb") + (match_operand:SI 1 "register_operand" "rb")] + UNSPEC_ARC_STKTIE))] + "" + "" + [(set_attr "length" "0") + (set_attr "iscompact" "false") + (set_attr "type" "block")] + ) + ;; include the arc-FPX instructions (include "fpx.md") -- 2.30.2