Re: [patch] Backtrace prints wrong argument value

Luis Machado
2007-09-17T13:05:01Z

[-- Attachment #1: Type: text/plain, Size: 592 bytes --]

:ADDPATCH PowerPC-64:

Daniel,

Thanks for reviewing.

Yeah, i definitely had issues with my editor and the tabs ended up being
expanded to spaces. Hopefully this version is correct now. I hope my
mail client doesn't mess the tabs.

> I guess this works, then? That's great.

Yes, it improves the situation quite a bit, since now only parameters
that are sure to be correct are displayed. If there's a chance of that
parameter being unreliable, then gdb won't display its value (optimized
out).

Best regards,

--
Luis Machado
IBM Linux Technology Center
e-mail: luisgpm@linux.vnet.ibm.com

[-- Attachment #2: call-clobbered-registers.diff --]
[-- Type: text/x-patch, Size: 3347 bytes --]

2007-09-17 Luis Machado <luisgpm@br.ibm.com>

* rs6000-tdep.c (ppc_dwarf2_frame_init_reg): New function.
(rs6000_gdbarch_init): Install ppc_dwarf2_frame_init_reg as
default dwarf2_frame_set_init_reg function.

Index: gdb/rs6000-tdep.c
===================================================================
--- gdb.orig/rs6000-tdep.c 2007-09-17 05:15:37.000000000 -0700
+++ gdb/rs6000-tdep.c 2007-09-17 05:41:23.000000000 -0700
@@ -3468,6 +3468,68 @@
return &rs6000_frame_base;
}

+/* DWARF-2 frame support. Used to handle the detection of
+ clobbered registers during function calls. */
+
+static void
+ppc_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
+ struct dwarf2_frame_state_reg *reg,
+ struct frame_info *next_frame)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ /* PPC32 and PPC64 ABI's are the same regarding volatile and
+ non-volatile registers. We will use the same code for both. */
+
+ /* Call-saved GP registers. */
+ if ((regnum >= tdep->ppc_gp0_regnum + 14
+ && regnum <= tdep->ppc_gp0_regnum + 31)
+ || (regnum == tdep->ppc_gp0_regnum + 1))
+ reg->how = DWARF2_FRAME_REG_SAME_VALUE;
+
+ /* Call-clobbered GP registers. */
+ if ((regnum >= tdep->ppc_gp0_regnum + 3
+ && regnum <= tdep->ppc_gp0_regnum + 12)
+ || (regnum == tdep->ppc_gp0_regnum))
+ reg->how = DWARF2_FRAME_REG_UNDEFINED;
+
+ /* Deal with FP registers, if supported. */
+ if (tdep->ppc_fp0_regnum >= 0)
+ {
+ /* Call-saved FP registers. */
+ if ((regnum >= tdep->ppc_fp0_regnum + 14
+ && regnum <= tdep->ppc_fp0_regnum + 31))
+ reg->how = DWARF2_FRAME_REG_SAME_VALUE;
+
+ /* Call-clobbered FP registers. */
+ if ((regnum >= tdep->ppc_fp0_regnum
+ && regnum <= tdep->ppc_fp0_regnum + 13))
+ reg->how = DWARF2_FRAME_REG_UNDEFINED;
+ }
+
+ /* Deal with ALTIVEC registers, if supported. */
+ if (tdep->ppc_vr0_regnum > 0 && tdep->ppc_vrsave_regnum > 0)
+ {
+ /* Call-saved Altivec registers. */
+ if ((regnum >= tdep->ppc_vr0_regnum + 20
+ && regnum <= tdep->ppc_vr0_regnum + 31)
+ || regnum == tdep->ppc_vrsave_regnum)
+ reg->how = DWARF2_FRAME_REG_SAME_VALUE;
+
+ /* Call-clobbered Altivec registers. */
+ if ((regnum >= tdep->ppc_vr0_regnum
+ && regnum <= tdep->ppc_vr0_regnum + 19))
+ reg->how = DWARF2_FRAME_REG_UNDEFINED;
+ }
+
+ /* Handle PC register and Stack Pointer correctly. */
+ if (regnum == gdbarch_pc_regnum (current_gdbarch))
+ reg->how = DWARF2_FRAME_REG_RA;
+ else if (regnum == gdbarch_sp_regnum (current_gdbarch))
+ reg->how = DWARF2_FRAME_REG_CFA;
+}
+
+
/* Initialize the current architecture based on INFO. If possible, re-use an
architecture from ARCHES, which is a list of architectures already created
during this debugging session.
@@ -3774,6 +3836,9 @@
frame_unwind_append_sniffer (gdbarch, dwarf2_frame_sniffer);
dwarf2_frame_set_adjust_regnum (gdbarch, rs6000_adjust_frame_regnum);

+ /* Frame handling. */
+ dwarf2_frame_set_init_reg (gdbarch, ppc_dwarf2_frame_init_reg);
+
/* Hook in ABI-specific overrides, if they have been registered. */
gdbarch_init_osabi (info, gdbarch);

@@ -3790,6 +3855,7 @@
tdep->ppc_vr0_regnum = 71;
tdep->ppc_vrsave_regnum = 104;
}
+
/* Fall Thru */