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MIPS: Correct MUSTBE32 interpretation in delay slot handling 

This change addresses `micromips_instruction_has_delay_slot' and
`mips16_instruction_has_delay_slot' that both incorrectly interpret
their MUSTBE32 argument.  Their callers assume that when the flag is
clear these functions will return 1 when any non-compact jump or branch
instruction is present at ADDR, while in fact they will only return 1
for 16-bit such instructions only.  This change makes the implementation
match the expectations.

	* mips-tdep.c (micromips_instruction_has_delay_slot): When
	!mustbe32 also return 1 for 32-bit instructions.
	(mips16_instruction_has_delay_slot): Likewise.  Add an
	explanatory comment.
This commit is contained in:
Maciej W. Rozycki 2014-10-05 21:50:47 +01:00
parent 24340e81fa
commit ae79065284
2 changed files with 20 additions and 8 deletions
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7
gdb/ChangeLog
View File

@ -1,3 +1,10 @@
2014-10-05 Maciej W. Rozycki <macro@codesourcery.com>
* mips-tdep.c (micromips_instruction_has_delay_slot): When
!mustbe32 also return 1 for 32-bit instructions.
(mips16_instruction_has_delay_slot): Likewise. Add an
explanatory comment.
2014-10-03 Maciej W. Rozycki <macro@codesourcery.com>
* elfread.c (elf_symtab_read): Also mark solib trampoline minimal

21
gdb/mips-tdep.c
View File

@ -7035,17 +7035,18 @@ micromips_instruction_has_delay_slot (struct gdbarch *gdbarch,
if (status)
return 0;
if (!mustbe32) /* 16-bit instructions. */
return (micromips_op (insn) == 0x11
/* 16-bit instructions. */
if ((micromips_op (insn) == 0x11
/* POOL16C: bits 010001 */
&& (b5s5_op (insn) == 0xc
&& (b5s5_op (insn) == 0xc
/* JR16: bits 010001 01100 */
|| (b5s5_op (insn) & 0x1e) == 0xe))
|| (b5s5_op (insn) & 0x1e) == 0xe))
/* JALR16, JALRS16: bits 010001 0111x */
|| (micromips_op (insn) & 0x37) == 0x23
|| (micromips_op (insn) & 0x37) == 0x23
/* BEQZ16, BNEZ16: bits 10x011 */
|| micromips_op (insn) == 0x33;
|| micromips_op (insn) == 0x33)
/* B16: bits 110011 */
return !mustbe32;
/* 32-bit instructions. */
if (micromips_op (insn) == 0x0)
@ -7091,6 +7092,10 @@ micromips_instruction_has_delay_slot (struct gdbarch *gdbarch,
/* JALX: bits 111100 */
}
/* Return non-zero if a MIPS16 instruction at ADDR has a branch delay
slot (i.e. it is a non-compact jump instruction). The instruction
must be 32-bit if MUSTBE32 is set or can be any instruction otherwise. */
static int
mips16_instruction_has_delay_slot (struct gdbarch *gdbarch, CORE_ADDR addr,
int mustbe32)
@ -7102,8 +7107,8 @@ mips16_instruction_has_delay_slot (struct gdbarch *gdbarch, CORE_ADDR addr,
if (status)
return 0;
if (!mustbe32)
return (inst & 0xf89f) == 0xe800; /* JR/JALR (16-bit instruction) */
if ((inst & 0xf89f) == 0xe800) /* JR/JALR (16-bit instruction) */
return !mustbe32;
return (inst & 0xf800) == 0x1800; /* JAL/JALX (32-bit instruction) */
}