Messages in this thread Patch in this message | | | From | Vineet Gupta <> | Subject | [PATCH 12/17] ARC: dw2 unwind: Elide a loop if DW_CFA_register not present | Date | Thu, 3 Dec 2015 18:11:10 +0530 |
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Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- arch/arc/kernel/unwind.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c index b1a520afcbcb..6eb377c102c6 100644 --- a/arch/arc/kernel/unwind.c +++ b/arch/arc/kernel/unwind.c @@ -149,7 +149,7 @@ struct unwind_state { uleb128_t reg, offs; } cfa; struct unwind_item regs[ARRAY_SIZE(reg_info)]; - unsigned stackDepth; + unsigned stackDepth:8, has_cfa_register:8; const u8 *label; const u8 *stack[MAX_STACK_DEPTH]; }; @@ -697,6 +697,7 @@ static int processCFI(const u8 *start, const u8 *end, unsigned long targetLoc, case DW_CFA_register: str = "cfa_register: "; value = get_uleb128(&ptr.p8, end); + state->has_cfa_register = 1; set_rule(value, Register, get_uleb128(&ptr.p8, end), state, str); break; case DW_CFA_remember_state: @@ -1010,11 +1011,18 @@ int arc_unwind(struct unwind_frame_info *frame) unw_debug("\nCFA reg: r%ld, off: %ld => [SP] 0x%lx\n", state.cfa.reg, state.cfa.offs, cfa); - for (i = 0; i < ARRAY_SIZE(state.regs); ++i) { - switch (state.regs[i].where) { - default: - break; - case Register: + /* + * For DW_CFA_register instruction, save registers initial state + * Note that a seperate pass is needed (vs. doing this in main loop below) + * to capture state of those regs at time of entry into function since + * the main loop below can possibly clobber them due to CFA ops of + * function being processed + * + * Since ARC gcc doesn't seem to generate those (ABI thing ?) try to + * optimize out the loop + */ + for (i = 0; state.has_cfa_register && i < ARRAY_SIZE(state.regs); ++i) { + if (state.regs[i].where == Register) { if (state.regs[i].value >= ARRAY_SIZE(reg_info)) return -EIO; switch (reg_info[state.regs[i].value].width) { @@ -1039,7 +1047,6 @@ int arc_unwind(struct unwind_frame_info *frame) default: return -EIO; } - break; } } -- 1.9.1
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