Branch prediction code cleanup

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index aebd3df..a4e3cc2 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,22 @@
+2001-07-04  Daniel Jacobowitz  <drow@mvista.com>
+       * mips-tdep.c (mips32_op): Correct offset.
+       (itype_op): Likewise.
+       (itype_rs): Fix formatting.
+       (itype_immediate): Fix formatting.
+       (jtype_op): Correct offset.
+       (jtype_target): Fix formatting.
+       (rtype_op): Correct offset.
+       (rtype_rs): Fix formatting.
+       (rtype_rt): Likewise.
+       (rtype_rd): Likewise.
+       (rtype_shamt): Likewise.
+       (rtype_funct): Likewise.
+
+       (mips32_next_pc):  Fix formatting and comments.  Recognize
+       coprocessor 1 branches.  Check the correct field for BLT family
+       branches.  Use itype_rt instead of itype_rs for the second register
+       of a BNE or BNEL branch.  Move (unreachable) default case.
+
 2001-07-04  Andrew Cagney  <ac131313@redhat.com>
 
        * ui-out.h (struct ui_out_impl): Add field is_mi_like_p.

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index d83c4d1..f723e46 100644 (file)
--- 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;