From 21daaaaffcbda47b724858dd99ee2082043ef2da Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Thu, 27 Nov 2014 11:37:54 +0800 Subject: [PATCH] Improve arm_skip_prologue by using arm_analyze_prologue Hi, I see many fails in dw2-dir-file-name.exp on arm target when test case is compiled with -marm, however, these fails are disappeared when test case is compiled with -mthumb. The difference of pass and fail shown below is that "0x000085d4 in" isn't printed out, but test case expects to see it. -Breakpoint 2, compdir_missing__ldir_missing__file_basename () at tmp-dw2-dir-file-name.c:999^M -(gdb) FAIL: gdb.dwarf2/dw2-dir-file-name.exp: compdir_missing__ldir_missing__file_basename: continue to breakpoint: compdir_missing__ldir_missing__file_basename +Breakpoint 2, 0x000085d4 in compdir_missing__ldir_missing__file_basename () at tmp-dw2-dir-file-name.c:999^M +(gdb) PASS: gdb.dwarf2/dw2-dir-file-name.exp: compdir_missing__ldir_missing__file_basename: continue to breakpoint: compdir_missing__ldir_missing__file_basename This difference is caused by setting breakpoint at the first instruction in the function (actually, the first instruction in prologue, at [1]), so that frame_show_address returns false, and print_frame doesn't print the address. 0x00008620 <+0>: push {r11} ; (str r11, [sp, #-4]!) <--[1] 0x00008624 <+4>: add r11, sp, #0 0x00008628 <+8>: ldr r3, [pc, #24] ; 0x8648 0x0000862c <+12>: ldr r3, [r3] 0x00008630 <+16>: add r3, r3, #1 0x00008634 <+20>: ldr r2, [pc, #12] ; 0x8648 Then, it must be the arm_skip_prologue's fault that unable to skip instructions in prologue. At the end of arm_skip_prologue, it matches several instructions, such as "str r(0123),[r11,#-nn]" and "str r(0123),[sp,#nn]", but "push {r11}" isn't handled. These instruction matching code in arm_skip_prologue, which can be regarded as leftover of development for many years, should be merged to arm_analyze_prologue and use arm_analyze_prologue in arm_skip_prologue. Here is the something like the history of arm_{skip,scan,analyze}_prologue. Around 2002, there are arm_skip_prologue and arm_scan_prologue, but code are duplicated to some extent. When match an instruction, both functions should be modified, for example in Michael Snyder's patch https://sourceware.org/ml/gdb-patches/2002-05/msg00205.html and Michael expressed the willingness to merge both into one. Daniel added code call thumb_analyze_prologue in arm_skip_prologue in 2006, but didn't handle its counterpart arm_analyze_prologue, which is added in 2010 however, the instructions matching at the bottom of arm_skip_prologue wasn't cleaned up. This patch is to merge them into arm_analyze_prologue. gdb: 2014-12-12 Yao Qi PR tdep/14261 * arm-tdep.c (arm_skip_prologue): Remove unused local variable 'skip_pc'. Remove code skipping prologue instructions, use arm_analyze_prologue instead. (arm_analyze_prologue): Stop the scanning for unrecognized instruction when skipping prologue. --- gdb/ChangeLog | 9 ++++++ gdb/arm-tdep.c | 75 ++++++++------------------------------------------ 2 files changed, 21 insertions(+), 63 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index c444ce77c07..bf1f80b58b6 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2014-12-12 Yao Qi + + PR tdep/14261 + * arm-tdep.c (arm_skip_prologue): Remove unused local variable + 'skip_pc'. Remove code skipping prologue instructions, use + arm_analyze_prologue instead. + (arm_analyze_prologue): Stop the scanning for unrecognized + instruction when skipping prologue. + 2014-12-12 Yao Qi * arm-tdep.c (arm_instruction_restores_sp): New function. diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c index 34070452e17..a4f99c58fb5 100644 --- a/gdb/arm-tdep.c +++ b/gdb/arm-tdep.c @@ -1388,7 +1388,6 @@ arm_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) { enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch); unsigned long inst; - CORE_ADDR skip_pc; CORE_ADDR func_addr, limit_pc; /* See if we can determine the end of the prologue via the symbol table. @@ -1462,65 +1461,8 @@ arm_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) /* Check if this is Thumb code. */ if (arm_pc_is_thumb (gdbarch, pc)) return thumb_analyze_prologue (gdbarch, pc, limit_pc, NULL); - - for (skip_pc = pc; skip_pc < limit_pc; skip_pc += 4) - { - inst = read_memory_unsigned_integer (skip_pc, 4, byte_order_for_code); - - /* "mov ip, sp" is no longer a required part of the prologue. */ - if (inst == 0xe1a0c00d) /* mov ip, sp */ - continue; - - if ((inst & 0xfffff000) == 0xe28dc000) /* add ip, sp #n */ - continue; - - if ((inst & 0xfffff000) == 0xe24dc000) /* sub ip, sp #n */ - continue; - - /* Some prologues begin with "str lr, [sp, #-4]!". */ - if (inst == 0xe52de004) /* str lr, [sp, #-4]! */ - continue; - - if ((inst & 0xfffffff0) == 0xe92d0000) /* stmfd sp!,{a1,a2,a3,a4} */ - continue; - - if ((inst & 0xfffff800) == 0xe92dd800) /* stmfd sp!,{fp,ip,lr,pc} */ - continue; - - /* Any insns after this point may float into the code, if it makes - for better instruction scheduling, so we skip them only if we - find them, but still consider the function to be frame-ful. */ - - /* We may have either one sfmfd instruction here, or several stfe - insns, depending on the version of floating point code we - support. */ - if ((inst & 0xffbf0fff) == 0xec2d0200) /* sfmfd fn, , [sp]! */ - continue; - - if ((inst & 0xffff8fff) == 0xed6d0103) /* stfe fn, [sp, #-12]! */ - continue; - - if ((inst & 0xfffff000) == 0xe24cb000) /* sub fp, ip, #nn */ - continue; - - if ((inst & 0xfffff000) == 0xe24dd000) /* sub sp, sp, #nn */ - continue; - - if ((inst & 0xffffc000) == 0xe54b0000 /* strb r(0123),[r11,#-nn] */ - || (inst & 0xffffc0f0) == 0xe14b00b0 /* strh r(0123),[r11,#-nn] */ - || (inst & 0xffffc000) == 0xe50b0000) /* str r(0123),[r11,#-nn] */ - continue; - - if ((inst & 0xffffc000) == 0xe5cd0000 /* strb r(0123),[sp,#nn] */ - || (inst & 0xffffc0f0) == 0xe1cd00b0 /* strh r(0123),[sp,#nn] */ - || (inst & 0xffffc000) == 0xe58d0000) /* str r(0123),[sp,#nn] */ - continue; - - /* Un-recognized instruction; stop scanning. */ - break; - } - - return skip_pc; /* End of prologue. */ + else + return arm_analyze_prologue (gdbarch, pc, limit_pc, NULL); } /* *INDENT-OFF* */ @@ -1905,10 +1847,17 @@ arm_analyze_prologue (struct gdbarch *gdbarch, continue; else { - /* The optimizer might shove anything into the prologue, - so we just skip what we don't recognize. */ + /* The optimizer might shove anything into the prologue, if + we build up cache (cache != NULL) from scanning prologue, + we just skip what we don't recognize and scan further to + make cache as complete as possible. However, if we skip + prologue, we'll stop immediately on unrecognized + instruction. */ unrecognized_pc = current_pc; - continue; + if (cache != NULL) + continue; + else + break; } } -- 2.30.2