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authorDaniel Jacobowitz <drow@false.org>2001-07-06 05:35:17 +0000
committerDaniel Jacobowitz <drow@false.org>2001-07-06 05:35:17 +0000
commite135b8899484dd4a3b7c4ee5cd5eea0b61e422c6 (patch)
tree04dbbe126ca26297098052c96b09489f9ca2bdc1 /gdb/mips-tdep.c
parent94bbb2c00d4c46aee0a9fa3677753034e842c125 (diff)
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Branch prediction code cleanup
Diffstat (limited to 'gdb/mips-tdep.c')
-rw-r--r--gdb/mips-tdep.c93
1 files changed, 53 insertions, 40 deletions
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index d83c4d1..f723e46 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -669,21 +669,21 @@ mips_fetch_instruction (CORE_ADDR addr)
/* These the fields of 32 bit mips instructions */
-#define mips32_op(x) (x >> 25)
-#define itype_op(x) (x >> 25)
-#define itype_rs(x) ((x >> 21)& 0x1f)
+#define mips32_op(x) (x >> 26)
+#define itype_op(x) (x >> 26)
+#define itype_rs(x) ((x >> 21) & 0x1f)
#define itype_rt(x) ((x >> 16) & 0x1f)
-#define itype_immediate(x) ( x & 0xffff)
+#define itype_immediate(x) (x & 0xffff)
-#define jtype_op(x) (x >> 25)
-#define jtype_target(x) ( x & 0x03fffff)
+#define jtype_op(x) (x >> 26)
+#define jtype_target(x) (x & 0x03ffffff)
-#define rtype_op(x) (x >>25)
-#define rtype_rs(x) ((x>>21) & 0x1f)
-#define rtype_rt(x) ((x>>16) & 0x1f)
-#define rtype_rd(x) ((x>>11) & 0x1f)
-#define rtype_shamt(x) ((x>>6) & 0x1f)
-#define rtype_funct(x) (x & 0x3f )
+#define rtype_op(x) (x >> 26)
+#define rtype_rs(x) ((x >> 21) & 0x1f)
+#define rtype_rt(x) ((x >> 16) & 0x1f)
+#define rtype_rd(x) ((x >> 11) & 0x1f)
+#define rtype_shamt(x) ((x >> 6) & 0x1f)
+#define rtype_funct(x) (x & 0x3f)
static CORE_ADDR
mips32_relative_offset (unsigned long inst)
@@ -706,25 +706,39 @@ mips32_next_pc (CORE_ADDR pc)
unsigned long inst;
int op;
inst = mips_fetch_instruction (pc);
- if ((inst & 0xe0000000) != 0) /* Not a special, junp or branch instruction */
+ if ((inst & 0xe0000000) != 0) /* Not a special, jump or branch instruction */
{
- if ((inst >> 27) == 5) /* BEQL BNEZ BLEZL BGTZE , bits 0101xx */
+ if (itype_op (inst) >> 2 == 5)
+ /* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx */
{
- op = ((inst >> 25) & 0x03);
+ op = (itype_op (inst) & 0x03);
switch (op)
{
- case 0:
- goto equal_branch; /* BEQL */
- case 1:
- goto neq_branch; /* BNEZ */
- case 2:
- goto less_branch; /* BLEZ */
- case 3:
- goto greater_branch; /* BGTZ */
+ case 0: /* BEQL */
+ goto equal_branch;
+ case 1: /* BNEL */
+ goto neq_branch;
+ case 2: /* BLEZL */
+ goto less_branch;
+ case 3: /* BGTZ */
+ goto greater_branch;
default:
pc += 4;
}
}
+ else if (itype_op (inst) == 17 && itype_rs (inst) == 8)
+ /* BC1F, BC1FL, BC1T, BC1TL: 010001 01000 */
+ {
+ int tf = itype_rt (inst) & 0x01;
+ int cnum = itype_rt (inst) >> 2;
+ int fcrcs = read_signed_register (FCRCS_REGNUM);
+ int cond = ((fcrcs >> 24) & 0x0e) | ((fcrcs >> 23) & 0x01);
+
+ if (((cond >> cnum) & 0x01) == tf)
+ pc += mips32_relative_offset (inst) + 4;
+ else
+ pc += 8;
+ }
else
pc += 4; /* Not a branch, next instruction is easy */
}
@@ -732,7 +746,7 @@ mips32_next_pc (CORE_ADDR pc)
{ /* This gets way messy */
/* Further subdivide into SPECIAL, REGIMM and other */
- switch (op = ((inst >> 26) & 0x07)) /* extract bits 28,27,26 */
+ switch (op = itype_op (inst) & 0x07) /* extract bits 28,27,26 */
{
case 0: /* SPECIAL */
op = rtype_funct (inst);
@@ -747,15 +761,15 @@ mips32_next_pc (CORE_ADDR pc)
pc += 4;
}
- break; /* end special */
+ break; /* end SPECIAL */
case 1: /* REGIMM */
{
- op = jtype_op (inst); /* branch condition */
- switch (jtype_op (inst))
+ op = itype_rt (inst); /* branch condition */
+ switch (op)
{
case 0: /* BLTZ */
- case 2: /* BLTXL */
- case 16: /* BLTZALL */
+ case 2: /* BLTZL */
+ case 16: /* BLTZAL */
case 18: /* BLTZALL */
less_branch:
if (read_signed_register (itype_rs (inst)) < 0)
@@ -763,7 +777,7 @@ mips32_next_pc (CORE_ADDR pc)
else
pc += 8; /* after the delay slot */
break;
- case 1: /* GEZ */
+ case 1: /* BGEZ */
case 3: /* BGEZL */
case 17: /* BGEZAL */
case 19: /* BGEZALL */
@@ -773,19 +787,19 @@ mips32_next_pc (CORE_ADDR pc)
else
pc += 8; /* after the delay slot */
break;
- /* All of the other intructions in the REGIMM catagory */
+ /* All of the other instructions in the REGIMM category */
default:
pc += 4;
}
}
- break; /* end REGIMM */
+ break; /* end REGIMM */
case 2: /* J */
case 3: /* JAL */
{
unsigned long reg;
reg = jtype_target (inst) << 2;
+ /* Upper four bits get never changed... */
pc = reg + ((pc + 4) & 0xf0000000);
- /* Whats this mysterious 0xf000000 adjustment ??? */
}
break;
/* FIXME case JALX : */
@@ -796,7 +810,7 @@ mips32_next_pc (CORE_ADDR pc)
/* Add 1 to indicate 16 bit mode - Invert ISA mode */
}
break; /* The new PC will be alternate mode */
- case 4: /* BEQ , BEQL */
+ case 4: /* BEQ, BEQL */
equal_branch:
if (read_signed_register (itype_rs (inst)) ==
read_signed_register (itype_rt (inst)))
@@ -804,15 +818,15 @@ mips32_next_pc (CORE_ADDR pc)
else
pc += 8;
break;
- case 5: /* BNE , BNEL */
+ case 5: /* BNE, BNEL */
neq_branch:
if (read_signed_register (itype_rs (inst)) !=
- read_signed_register (itype_rs (inst)))
+ read_signed_register (itype_rt (inst)))
pc += mips32_relative_offset (inst) + 4;
else
pc += 8;
break;
- case 6: /* BLEZ , BLEZL */
+ case 6: /* BLEZ, BLEZL */
less_zero_branch:
if (read_signed_register (itype_rs (inst) <= 0))
pc += mips32_relative_offset (inst) + 4;
@@ -820,14 +834,13 @@ mips32_next_pc (CORE_ADDR pc)
pc += 8;
break;
case 7:
- greater_branch: /* BGTZ BGTZL */
+ default:
+ greater_branch: /* BGTZ, BGTZL */
if (read_signed_register (itype_rs (inst) > 0))
pc += mips32_relative_offset (inst) + 4;
else
pc += 8;
break;
- default:
- pc += 8;
} /* switch */
} /* else */
return pc;