Re: [PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
Mark Wielaard writes: > https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=no-Rust-old > if someone wants to push that, to merge for a v4. Sorry, missed that part, taking care of merging it right now :) https://github.com/Rust-GCC/gccrs/pull/1649 Thanks, Marc
Re: [PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
> "Mark" == Mark Wielaard writes: Mark> DW_LANG_Rust_old was used by old rustc compilers <= 2016 before DWARF5 Mark> assigned an official number. It might be recognized by some Mark> debuggers. FWIW I wouldn't worry about it any more. We could probably just remove the '_old' constant. Tom
Re: [PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
On Sun, Oct 30, 2022 at 04:22:34PM +0100, Mark Wielaard wrote: > Hi, > > On Wed, Oct 26, 2022 at 10:39:09AM +0200, Jakub Jelinek wrote: > > I must say I don't understand nor like this DW_LANG_Rust_old stuff at all. > > Other languages don't do similar dances. > > Look for D, or Go. Neither of them has any non-standard lang code as > > fallback, they use the DWARF assigned DW_LANG_* code, and DW_LANG_C as > > fallback. On most arches, DWARF 5 is the default anyway, or non-strict > > DWARF at least. Where neither is enabled because of prehistoric or buggy > > DWARF consumers, it is unlikely they'd handle Rust sanely anyway. > > Just follow what Go does in the same function. > > DW_LANG_Rust_old was used by old rustc compilers <= 2016 before DWARF5 > assigned an official number. It might be recognized by some > debuggers. But I agree that these days it doesn't really make sense to > emit it. When producing strict DWARF it is also slightly odd to emit a > non-standard language code. So I agree that it makes sense to do what > Go does, always emit DW_LANG_Rust unless we emit strict DWARF for > versions before 5 (and then just fall back to DW_LANG_C). > > The attached patch (against "upstream gccrs") does that. I kept the > oldlang.rs testcase just to see that the -gstrict-dwarf -gdwarf-3 case > does something sane. > > The only "issue" is that is_rust () depends on the comp_unit_die > DW_AT_language being DW_LANG_Rust. But the only usage of is_rust > already depends on strict DWARF. > > https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=no-Rust-old > if someone wants to push that, to merge for a v4. LGTM, thanks. Jakub
Re: [PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
Hi,
On Wed, Oct 26, 2022 at 10:39:09AM +0200, Jakub Jelinek wrote:
> I must say I don't understand nor like this DW_LANG_Rust_old stuff at all.
> Other languages don't do similar dances.
> Look for D, or Go. Neither of them has any non-standard lang code as
> fallback, they use the DWARF assigned DW_LANG_* code, and DW_LANG_C as
> fallback. On most arches, DWARF 5 is the default anyway, or non-strict
> DWARF at least. Where neither is enabled because of prehistoric or buggy
> DWARF consumers, it is unlikely they'd handle Rust sanely anyway.
> Just follow what Go does in the same function.
DW_LANG_Rust_old was used by old rustc compilers <= 2016 before DWARF5
assigned an official number. It might be recognized by some
debuggers. But I agree that these days it doesn't really make sense to
emit it. When producing strict DWARF it is also slightly odd to emit a
non-standard language code. So I agree that it makes sense to do what
Go does, always emit DW_LANG_Rust unless we emit strict DWARF for
versions before 5 (and then just fall back to DW_LANG_C).
The attached patch (against "upstream gccrs") does that. I kept the
oldlang.rs testcase just to see that the -gstrict-dwarf -gdwarf-3 case
does something sane.
The only "issue" is that is_rust () depends on the comp_unit_die
DW_AT_language being DW_LANG_Rust. But the only usage of is_rust
already depends on strict DWARF.
https://code.wildebeest.org/git/user/mjw/gccrs/commit/?h=no-Rust-old
if someone wants to push that, to merge for a v4.
Thanks,
Mark>From cdcfe27cfba23402f91200c64c1ef8e0bf3528a0 Mon Sep 17 00:00:00 2001
From: Mark Wielaard
Date: Sun, 30 Oct 2022 16:03:16 +0100
Subject: [PATCH] dwarf2out.c: Don't emit DW_LANG_Rust_old
DW_LANG_Rust_old is a non-standard DWARF language code used by old
rustc compilers before DWARF5 (released in 2017). Just always emit
DW_LANG_Rust unless producing strict DWARF for versions before 5.
And in that old strict DWARF case just emit DW_LANG_C instead of a
non-standard language code.
---
gcc/dwarf2out.cc| 14 +-
gcc/testsuite/rust/debug/oldlang.rs | 4 ++--
2 files changed, 7 insertions(+), 11 deletions(-)
diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index 7b9d5ae33fc..87c0d103a27 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -5600,14 +5600,15 @@ is_fortran (const_tree decl)
return is_fortran ();
}
-/* Return TRUE if the language is Rust. */
+/* Return TRUE if the language is Rust.
+ Note, returns FALSE for dwarf_version < 5 && dwarf_strict. */
static inline bool
is_rust ()
{
unsigned int lang = get_AT_unsigned (comp_unit_die (), DW_AT_language);
- return lang == DW_LANG_Rust || lang == DW_LANG_Rust_old;
+ return lang == DW_LANG_Rust;
}
/* Return TRUE if the language is Ada. */
@@ -25216,13 +25217,6 @@ gen_compile_unit_die (const char *filename)
}
else if (strcmp (language_string, "GNU F77") == 0)
language = DW_LANG_Fortran77;
- else if (strcmp (language_string, "GNU Rust") == 0)
-{
- if (dwarf_version >= 5 || !dwarf_strict)
- language = DW_LANG_Rust;
- else
- language = DW_LANG_Rust_old;
-}
else if (dwarf_version >= 3 || !dwarf_strict)
{
if (strcmp (language_string, "GNU Ada") == 0)
@@ -25248,6 +25242,8 @@ gen_compile_unit_die (const char *filename)
{
if (strcmp (language_string, "GNU Go") == 0)
language = DW_LANG_Go;
+ else if (strcmp (language_string, "GNU Rust") == 0)
+ language = DW_LANG_Rust;
}
}
/* Use a degraded Fortran setting in strict DWARF2 so is_fortran works. */
diff --git a/gcc/testsuite/rust/debug/oldlang.rs b/gcc/testsuite/rust/debug/oldlang.rs
index ddacf0e4392..648d6b78f06 100644
--- a/gcc/testsuite/rust/debug/oldlang.rs
+++ b/gcc/testsuite/rust/debug/oldlang.rs
@@ -1,6 +1,6 @@
fn main () {
// { dg-do compile }
// { dg-options "-gstrict-dwarf -gdwarf-3 -dA" }
-// DW_LANG_Rust_old is 0x9000
-// { dg-final { scan-assembler "0x9000\[ \t]\[^\n\r]* DW_AT_language" } } */
+// Strict DWARF < 5 uses DW_LANG_C = 0x0002
+// { dg-final { scan-assembler "0x2\[ \t]\[^\n\r]* DW_AT_language" } } */
}
--
2.30.2
Re: [PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
On Wed, Oct 26, 2022 at 10:17:26AM +0200, arthur.co...@embecosm.com wrote:
> @@ -25201,6 +25215,13 @@ gen_compile_unit_die (const char *filename)
> }
>else if (strcmp (language_string, "GNU F77") == 0)
> language = DW_LANG_Fortran77;
> + else if (strcmp (language_string, "GNU Rust") == 0)
> +{
> + if (dwarf_version >= 5 || !dwarf_strict)
> + language = DW_LANG_Rust;
> + else
> + language = DW_LANG_Rust_old;
> +}
I must say I don't understand nor like this DW_LANG_Rust_old stuff at all.
Other languages don't do similar dances.
Look for D, or Go. Neither of them has any non-standard lang code as
fallback, they use the DWARF assigned DW_LANG_* code, and DW_LANG_C as
fallback. On most arches, DWARF 5 is the default anyway, or non-strict
DWARF at least. Where neither is enabled because of prehistoric or buggy
DWARF consumers, it is unlikely they'd handle Rust sanely anyway.
Just follow what Go does in the same function.
Jakub
[PATCH Rust front-end v3 01/46] Use DW_ATE_UTF for the Rust 'char' type
From: Tom Tromey
The Rust 'char' type should use the DWARF DW_ATE_UTF encoding.
---
gcc/dwarf2out.cc | 23 ++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index e3920c898f5..a8bccbabca4 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -5600,6 +5600,16 @@ is_fortran (const_tree decl)
return is_fortran ();
}
+/* Return TRUE if the language is Rust. */
+
+static inline bool
+is_rust ()
+{
+ unsigned int lang = get_AT_unsigned (comp_unit_die (), DW_AT_language);
+
+ return lang == DW_LANG_Rust || lang == DW_LANG_Rust_old;
+}
+
/* Return TRUE if the language is Ada. */
static inline bool
@@ -13231,7 +13241,11 @@ base_type_die (tree type, bool reverse)
}
if (TYPE_STRING_FLAG (type))
{
- if (TYPE_UNSIGNED (type))
+ if ((dwarf_version >= 4 || !dwarf_strict)
+ && is_rust ()
+ && int_size_in_bytes (type) == 4)
+ encoding = DW_ATE_UTF;
+ else if (TYPE_UNSIGNED (type))
encoding = DW_ATE_unsigned_char;
else
encoding = DW_ATE_signed_char;
@@ -25201,6 +25215,13 @@ gen_compile_unit_die (const char *filename)
}
else if (strcmp (language_string, "GNU F77") == 0)
language = DW_LANG_Fortran77;
+ else if (strcmp (language_string, "GNU Rust") == 0)
+{
+ if (dwarf_version >= 5 || !dwarf_strict)
+ language = DW_LANG_Rust;
+ else
+ language = DW_LANG_Rust_old;
+}
else if (dwarf_version >= 3 || !dwarf_strict)
{
if (strcmp (language_string, "GNU Ada") == 0)
--
2.37.2
