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Re: [PATCH v2 13/13] Add hook for modifying debug info for address spaces


On 10/21/2015 04:53 AM, H.J. Lu wrote:
On Tue, Oct 20, 2015 at 2:27 PM, Richard Henderson <rth@redhat.com> wrote:
---
  gcc/config/i386/i386.c | 21 +++++++++++++++++++++
  gcc/doc/tm.texi        |  7 +++++++
  gcc/doc/tm.texi.in     |  2 ++
  gcc/dwarf2out.c        | 48 +++++++++++++++++++++++++++++-------------------
  gcc/target.def         | 10 ++++++++++
  gcc/targhooks.c        |  8 ++++++++
  gcc/targhooks.h        |  1 +
  7 files changed, 78 insertions(+), 19 deletions(-)

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 8f833d1..9fb0fac 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -53707,6 +53707,27 @@ ix86_addr_space_convert (rtx op, tree from_type, tree to_type)
  #undef TARGET_ADDR_SPACE_CONVERT
  #define TARGET_ADDR_SPACE_CONVERT ix86_addr_space_convert

+static int
+ix86_addr_space_debug (addr_space_t as)
+{
+  /* Represent debugging for address spaces with DW_AT_segment,
+     and the dwarf register for fsbase/gsbase.  */
+  if (as == ADDR_SPACE_SEG_TLS)
+    as = DEFAULT_TLS_SEG_REG;
+
+  /* ??? These register numbers are defined in the x86-64 abi,
+     but there is no corresponding definition for the i386 abi.
+     That said, {58,59} appear to be reserved, so perhaps best
+     to use the same numbers in the 32-bit abi.  */
+  if (as == ADDR_SPACE_SEG_FS)
+    return ~58;  /* dwarf fsbase */
+  else if (as == ADDR_SPACE_SEG_GS)
+    return ~59;  /* dwarf gsbase */
+  gcc_unreachable ();
+}

This is wrong for i386 psABI.  Please use the DWARF register
numbers listed in Table 2.14: DWARF Register Number Mapping
in Intel386 psABI:

https://github.com/hjl-tools/x86-psABI/wiki/X86-psABI

Segment Register ES 40 %es
Segment Register CS 41 %cs
Segment Register SS 42 %ss
Segment Register DS 43 %ds
Segment Register FS 44 %fs
Segment Register GS 45 %gs

I'm not looking for the segment register (aka descriptor), I'm looking for the segment base. Not the same thing.

As I note in the comment, there is no such definition in the i386 psabi, while there is in the x86-64 psabi.


r~


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