[Patch] fix for PR:1291

[kewarken <kewarken@qnx.com>]

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This patch addresses an issue with SH processors where gdb cannot
backtrace out of function with more than 256 bytes of local variables.

Code such as:

sub1()
{
        int buf[64];
}

sub2()
{
        int buf[65];
}

generates prologues such as:

sub1:
	mov.l	r14,@-r15
	add	#-128,r15
	add	#-128,r15
	mov	r15,r14
.L8:
	mov.w	.L9,r7
	add	r7,r14
	mov	r14,r15
	mov.l	@r15+,r14
	rts
	nop
	.align 1
.L9:
	.short	256

and

sub2:
	mov.l	r14,@-r15
	mov.w	.L11,r3
	sub	r3,r15
	mov	r15,r14
.L10:
	mov.w	.L11,r7
	add	r7,r14
	mov	r14,r15
	mov.l	@r15+,r14
	rts
	nop
	.align 1
.L11:
	.short	260


The second form is not recognized properly by the frame code in gdb.  In
the gcc 3 series, r1 is used instead of r3 so this patch expands on the
original patch attached to the PR.

Credit to inaba@src.ricoh.co.jp for his original find and patch and to
Colin Burgess for noting the differences between gcc 2 and 3.

ChangeLog:

2003-09-16  Kris Warkentin  <kewarken@qnx.com>

	* sh-tdep.c: Properly detect frame prologues for functions with
	more than 256 bytes of local variables.

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Index: sh-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/sh-tdep.c,v
retrieving revision 1.136
diff -u -r1.136 sh-tdep.c
--- sh-tdep.c	21 Aug 2003 00:01:31 -0000	1.136
+++ sh-tdep.c	16 Sep 2003 18:35:39 -0000
@@ -622,13 +622,39 @@
    r15+imm-->r15 */
 #define IS_ADD_SP(x) 		(((x) & 0xff00) == 0x7f00)
 
-#define IS_MOV_R3(x) 		(((x) & 0xff00) == 0x1a00)
+/* MOV #imm,r3     11100011iiiiiiii
+   imm-->r3 */
+#define IS_MOV_R3(x) (((x) & 0xff00) == 0xe300)
 #define IS_SHLL_R3(x)		((x) == 0x4300)
 
 /* ADD r3,r15      0011111100111100
    r15+r3-->r15 */
 #define IS_ADD_R3SP(x)		((x) == 0x3f3c)
 
+/* MOV.W @(disp, pc), r1     10010001dddddddd
+   (disp * 2 + pc + 4)-->r1 */
+#define IS_MOVW_R1(x) (((x) & 0xff00) == 0x9100)
+
+/* MOV.L @(disp, pc), r1     11010001dddddddd
+   (disp * 4 + pc + 4)-->r1 */
+#define IS_MOVL_R1(x) (((x) & 0xff00) == 0xd100)
+
+/* SUB r1,r15      00111111100011000
+   r15-r1-->r15 */
+#define IS_SUB_R1SP(x) ((x) == 0x3f18)
+
+/* MOV.W @(disp, pc), r3     10010011dddddddd
+   (disp * 2 + pc + 4)-->r3 */
+#define IS_MOVW_R3(x) (((x) & 0xff00) == 0x9300)
+
+/* MOV.L @(disp, pc), r3     11010011dddddddd
+   (disp * 4 + pc + 4)-->r3 */
+#define IS_MOVL_R3(x) (((x) & 0xff00) == 0xd300)
+
+/* SUB r3,r15      00111111100111000
+   r15-r3-->r15 */
+#define IS_SUB_R3SP(x) ((x) == 0x3f38)
+
 /* FMOV.S FRm,@-Rn  Rn-4-->Rn, FRm-->(Rn)     1111nnnnmmmm1011
    FMOV DRm,@-Rn    Rn-8-->Rn, DRm-->(Rn)     1111nnnnmmm01011
    FMOV XDm,@-Rn    Rn-8-->Rn, XDm-->(Rn)     1111nnnnmmm11011 */
@@ -696,8 +722,11 @@
     {
       int w = read_memory_integer (here, 2);
       here += 2;
-      if (IS_FMOV (w) || IS_PUSH (w) || IS_STS (w) || IS_MOV_R3 (w)
-	  || IS_ADD_R3SP (w) || IS_ADD_SP (w) || IS_SHLL_R3 (w) 
+      if (IS_FMOV (w) || IS_PUSH (w) || IS_STS (w) 
+	  || IS_MOV_R3 (w)
+	  || IS_MOVW_R3 (w) || IS_MOVL_R3 (w) || IS_SUB_R3SP (w) || IS_ADD_R3SP (w) 
+	  || IS_MOVW_R1 (w) || IS_MOVL_R1 (w) || IS_SUB_R1SP (w) 
+	  || IS_ADD_SP (w) || IS_SHLL_R3 (w) 
 	  || IS_ARG_MOV (w) || IS_MOV_TO_R14 (w))
 	{
 	  start_pc = here;
@@ -1101,6 +1130,7 @@
   int pc;
   int opc;
   int insn;
+  int r1_val = 0;
   int r3_val = 0;
   char *dummy_regs = deprecated_generic_find_dummy_frame (get_frame_pc (fi),
 							  get_frame_base (fi));
@@ -1167,6 +1197,30 @@
 	{
 	  depth += -r3_val;
 	}
+      else if (IS_MOVW_R1 (insn))
+	{
+	  r1_val = read_memory_integer (pc + 4 + (insn & 0xff) * 2, 2);
+	}
+      else if (IS_MOVL_R1 (insn))
+	{
+	  r1_val = read_memory_integer (pc + 4 + (insn & 0xff) * 4, 4);
+	}
+      else if (IS_SUB_R1SP (insn))
+	{
+	  depth += r1_val;
+	}
+      else if (IS_MOVW_R3 (insn))
+	{
+	  r3_val = read_memory_integer (pc + 4 + (insn & 0xff) * 2, 2);
+	}
+      else if (IS_MOVL_R3 (insn))
+	{
+	  r3_val = read_memory_integer (pc + 4 + (insn & 0xff) * 4, 4);
+	}
+      else if (IS_SUB_R3SP (insn))
+	{
+	  depth += r3_val;
+	}
       else if (IS_ADD_SP (insn))
 	{
 	  depth -= ((insn & 0xff) ^ 0x80) - 0x80;
@@ -1642,6 +1696,7 @@
   int pc;
   int opc;
   int insn;
+  int r1_val = 0;
   int r3_val = 0;
   char *dummy_regs = deprecated_generic_find_dummy_frame (get_frame_pc (fi), get_frame_base (fi));
   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch); 
@@ -1707,6 +1762,30 @@
       else if (IS_ADD_R3SP (insn))
 	{
 	  depth += -r3_val;
+	}
+      else if (IS_MOVW_R1 (insn))
+	{
+	  r1_val = read_memory_integer (pc + 4 + (insn & 0xff) * 2, 2);
+	}
+      else if (IS_MOVL_R1 (insn))
+	{
+	  r1_val = read_memory_integer (pc + 4 + (insn & 0xff) * 4, 4);
+	}
+      else if (IS_SUB_R1SP (insn))
+	{
+	  depth += r1_val;
+	}
+      else if (IS_MOVW_R3 (insn))
+	{
+	  r3_val = read_memory_integer (pc + 4 + (insn & 0xff) * 2, 2);
+	}
+      else if (IS_MOVL_R3 (insn))
+	{
+	  r3_val = read_memory_integer (pc + 4 + (insn & 0xff) * 4, 4);
+	}
+      else if (IS_SUB_R3SP (insn))
+	{
+	  depth += r3_val;
 	}
       else if (IS_ADD_SP (insn))
 	{