From 540314bdd87c7478d21b44dd4856d937bcc1479b Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Wed, 2 Jul 2014 14:45:12 +0800 Subject: [PATCH] Match instruction adjusts SP in thumb This is a refactor patch, that moves matching instructions adjusting SP into a new function, thumb_instruction_restores_sp. The second call to thumb_instruction_restores_sp in thumb_in_function_epilogue_p is a little different from the original. The original code matches 'POP without PC', but thumb_in_function_epilogue_p matches 'POP (with and without PC)'. However, GDB found one instruction about return and is scanning the previous instruction, which should be an instruction about return too, so the code change doesn't affect the functionality. gdb: 2014-07-11 Yao Qi * arm-tdep.c (thumb_instruction_restores_sp): New function. (thumb_in_function_epilogue_p): Call thumb_instruction_restores_sp. --- gdb/ChangeLog | 6 ++++++ gdb/arm-tdep.c | 25 ++++++++++++++----------- 2 files changed, 20 insertions(+), 11 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 112a869..7bc1d03 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,11 @@ 2014-07-11 Yao Qi + * arm-tdep.c (thumb_instruction_restores_sp): New function. + (thumb_in_function_epilogue_p): Call + thumb_instruction_restores_sp. + +2014-07-11 Yao Qi + * arm-tdep.c (thumb_analyze_prologue): Don't match instruction 'add sp, #imm'. (thumb_in_function_epilogue_p): Don't match 'sub sp, #imm'. diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c index 6b1cf3c..0e7d9c2 100644 --- a/gdb/arm-tdep.c +++ b/gdb/arm-tdep.c @@ -685,6 +685,17 @@ thumb2_instruction_changes_pc (unsigned short inst1, unsigned short inst2) return 0; } +/* Return 1 if the 16-bit Thumb instruction INSN restores SP in + epilogue, 0 otherwise. */ + +static int +thumb_instruction_restores_sp (unsigned short insn) +{ + return (insn == 0x46bd /* mov sp, r7 */ + || (insn & 0xff80) == 0xb000 /* add sp, imm */ + || (insn & 0xfe00) == 0xbc00); /* pop */ +} + /* Analyze a Thumb prologue, looking for a recognizable stack frame and frame pointer. Scan until we encounter a store that could clobber the stack frame unexpectedly, or an unknown instruction. @@ -3257,14 +3268,10 @@ thumb_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc) found_return = 1; else if (insn == 0x46f7) /* mov pc, lr */ found_return = 1; - else if (insn == 0x46bd) /* mov sp, r7 */ - found_stack_adjust = 1; - else if ((insn & 0xff80) == 0xb000) /* add sp, imm */ - found_stack_adjust = 1; - else if ((insn & 0xfe00) == 0xbc00) /* pop */ + else if (thumb_instruction_restores_sp (insn)) { found_stack_adjust = 1; - if (insn & 0x0100) /* include PC. */ + if ((insn & 0xfe00) == 0xbd00) /* pop */ found_return = 1; } else if (thumb_insn_size (insn) == 4) /* 32-bit Thumb-2 instruction */ @@ -3317,11 +3324,7 @@ thumb_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc) insn = extract_unsigned_integer (buf, 2, byte_order_for_code); insn2 = extract_unsigned_integer (buf + 2, 2, byte_order_for_code); - if (insn2 == 0x46bd) /* mov sp, r7 */ - found_stack_adjust = 1; - else if ((insn2 & 0xff80) == 0xb000) /* add sp, imm */ - found_stack_adjust = 1; - else if ((insn2 & 0xff00) == 0xbc00) /* pop without PC */ + if (thumb_instruction_restores_sp (insn2)) found_stack_adjust = 1; else if (insn == 0xe8bd) /* ldm.w sp!, */ found_stack_adjust = 1; -- 2.7.4