X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=gdb%2Fgdbarch.sh;h=2f9fbbc56cd78cbc5600a9a310454646dc08b07a;hb=6b78c3f83c8bcbfa714aab7627ece9673b2d602a;hp=59493d8c21512b2b85d10cf80c000b91057b1760;hpb=37eedb39824dc26c82a92b5515a352d7de0c9b5b;p=deliverable%2Fbinutils-gdb.git

diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 59493d8c21..2f9fbbc56c 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1030,6 +1030,31 @@ M;int;stap_is_single_operand;const char *s;s
 # parser), and should advance the buffer pointer (p->arg).
 M;int;stap_parse_special_token;struct stap_parse_info *p;p
 
+# Perform arch-dependent adjustments to a register name.
+#
+# In very specific situations, it may be necessary for the register
+# name present in a SystemTap probe's argument to be handled in a
+# special way.  For example, on i386, GCC may over-optimize the
+# register allocation and use smaller registers than necessary.  In
+# such cases, the client that is reading and evaluating the SystemTap
+# probe (ourselves) will need to actually fetch values from the wider
+# version of the register in question.
+#
+# To illustrate the example, consider the following probe argument
+# (i386):
+#
+#    4@%ax
+#
+# This argument says that its value can be found at the %ax register,
+# which is a 16-bit register.  However, the argument's prefix says
+# that its type is "uint32_t", which is 32-bit in size.  Therefore, in
+# this case, GDB should actually fetch the probe's value from register
+# %eax, not %ax.  In this scenario, this function would actually
+# replace the register name from %ax to %eax.
+#
+# The rationale for this can be found at PR breakpoints/24541.
+M;std::string;stap_adjust_register;struct stap_parse_info *p, const std::string \&regname, int regnum;p, regname, regnum
+
 # DTrace related functions.
 
 # The expression to compute the NARTGth+1 argument to a DTrace USDT probe.