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Re: PowerPC prologue analysis
Daniel Jacobowitz wrote:
On Tue, Jul 29, 2008 at 11:42:29AM -0400, Aleksandar Ristovski wrote:
And for the reference: Daniel's patch (
http://sourceware.org/ml/gdb-patches/2007-12/msg00111.html ) does
solve the problem with not all registers saved.
Why is the patch not in HEAD gdb?
There's a couple of questions in the posting and I never figured out
the answers to them. I'll be back to them at some point.
May I suggest that you break the patch in two patches: one dealing with not-all-registers-saved (i.e. gpr_mask) and the rest?
I extracted the gpr_mask part here with the testsuite changes and I believe this part of the patch is safe to apply.
Attached: Fragment extracted from Daniel's patch.
Index: gdb/rs6000-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v
retrieving revision 1.318
diff -u -p -r1.318 rs6000-tdep.c
--- gdb/rs6000-tdep.c 15 Jul 2008 18:32:06 -0000 1.318
+++ gdb/rs6000-tdep.c 29 Jul 2008 16:27:53 -0000
@@ -117,6 +117,7 @@ struct rs6000_framedata
by which we decrement sp to allocate
the frame */
int saved_gpr; /* smallest # of saved gpr */
+ unsigned int gpr_mask; /* Each bit is an individual saved GPR. */
int saved_fpr; /* smallest # of saved fpr */
int saved_vr; /* smallest # of saved vr */
int saved_ev; /* smallest # of saved ev */
@@ -1275,6 +1276,10 @@ skip_prologue (struct gdbarch *gdbarch,
{
reg = GET_SRC_REG (op);
+ if ((op & 0xfc1f0000) == 0xbc010000)
+ fdata->gpr_mask |= ~((1U << reg) - 1);
+ else
+ fdata->gpr_mask |= 1U << reg;
if (fdata->saved_gpr == -1 || fdata->saved_gpr > reg)
{
fdata->saved_gpr = reg;
@@ -1678,11 +1683,15 @@ skip_prologue (struct gdbarch *gdbarch,
else
{
+ unsigned int all_mask = ~((1U << fdata->saved_gpr) - 1);
+
/* Not a recognized prologue instruction.
Handle optimizer code motions into the prologue by continuing
the search if we have no valid frame yet or if the return
- address is not yet saved in the frame. */
- if (fdata->frameless == 0 && fdata->nosavedpc == 0)
+ address is not yet saved in the frame. Also skip instructions
+ if some of the GPRs expected to be saved are not yet saved. */
+ if (fdata->frameless == 0 && fdata->nosavedpc == 0
+ && (fdata->gpr_mask & all_mask) == all_mask)
break;
if (op == 0x4e800020 /* blr */
@@ -2573,7 +2582,8 @@ rs6000_frame_cache (struct frame_info *t
CORE_ADDR gpr_addr = cache->base + fdata.gpr_offset;
for (i = fdata.saved_gpr; i < ppc_num_gprs; i++)
{
- cache->saved_regs[tdep->ppc_gp0_regnum + i].addr = gpr_addr;
+ if (fdata.gpr_mask & (1U << i))
+ cache->saved_regs[tdep->ppc_gp0_regnum + i].addr = gpr_addr;
gpr_addr += wordsize;
}
}
Index: gdb/testsuite/gdb.arch/powerpc-prologue.exp
===================================================================
--- gdb/testsuite/gdb.arch/powerpc-prologue.exp (revision 197)
+++ gdb/testsuite/gdb.arch/powerpc-prologue.exp (working copy)
@@ -64,7 +64,7 @@ gdb_test "backtrace 10" \
"backtrace in PIC"
gdb_test "info frame" \
- ".*Saved registers:.*r30 at.*r31 at.*pc at.*lr at.*" \
+ ".*Saved registers:.*r30 at.*pc at.*lr at.*" \
"saved registers in PIC"
# Testcase for scheduled prologue.
@@ -84,5 +84,5 @@ gdb_test "backtrace 10" \
"backtrace in optimized"
gdb_test "info frame" \
- ".*Saved registers:.*r30 at.*r31 at.*pc at.*lr at.*" \
+ ".*Saved registers:.*r30 at.*pc at.*lr at.*" \
"saved registers in optimized"