RE: [PATCH] Fix for incorrect breakpoint set in case of flang compiled binary

["Sharma, Alok Kumar" <AlokKumar.Sharma@amd.com>]

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Thanks Andrew. Please find the updated patch. I shall be committing this.

    gdb/ChangeLog

          * amd64-tdep.c (amd64_skip_prologue): Using symbol table
          to find the end of prologue for flang compiled binaries.
          * arm-tdep.c (arm_skip_prologue): Likewise.
          * i386-tdep.c (i386_skip_prologue): Likewise.
          * producer.c (producer_is_llvm): New function.
          (producer_parsing_tests): Added new tests for clang/flang.
          * producer.h (producer_is_llvm): New declaration.

    gdb/testsuite/ChangeLog

          * gdb.fortran/vla-type.exp: Skip commands not required for
          the Flang compiled binaries after prologue fix.

Regards,
Alok

-----Original Message-----
From: Andrew Burgess <andrew.burgess@embecosm.com> 
Sent: Wednesday, August 19, 2020 6:40 PM
To: Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>
Cc: Tom Tromey <tom@tromey.com>; gdb-patches@sourceware.org; George, Jini Susan <JiniSusan.George@amd.com>; Achra, Nitika <Nitika.Achra@amd.com>
Subject: Re: [PATCH] Fix for incorrect breakpoint set in case of flang compiled binary

[CAUTION: External Email]

* Sharma, Alok Kumar <AlokKumar.Sharma@amd.com> [2020-08-18 12:53:10 +0000]:

> Thanks Tom and Andrew for your comments. Hopefully addressed in the attached updated patch.
>
> Please find my below answers for your queries.
>
> > We have the files producer.{c,h} that wrap up tests just like this one.  If feels like we should add a new test to those files that matches all clang backend based compilers, then make use of this new test throughout.
> > I'd keep the name of the test fairly generic, the important thing here is the backend technology right, not the frontend language?  So if I added a new language with a clang backend I'd likely run into the same issues.
> Thanks for your suggestion. I have updated the patch for same.
>
> > Space before "(".
> Though the code is moved, I have taken care of the comment in general.
>
> > Does it really start with a space?  That seems weird.
> Agreed but it has space at the start.
>
> >> +# break main for Flang compiler already breaks here
> > Do you know why?
> Line number 46 is the place where breakpoint to main is hit for Flang compiled binary and that looks Okey.
> Below is the snippet from gdb.fortran/
> ------------------------------------------
>     16  program vla_struct
>     17    type :: one
>     18      integer, allocatable :: ivla (:, :, :)
>     19    end type one
>     20    type :: two
>     21      integer, allocatable :: ivla1 (:, :, :)
>     22      integer, allocatable :: ivla2 (:, :)
>     23    end type two
>     24    type :: three
>     25      integer :: ivar
>     26      integer, allocatable :: ivla (:)
>     27    end type three
>     28    type :: four
>     29      integer, allocatable :: ivla (:)
>     30      integer :: ivar
>     31    end type four
>     32    type :: five
>     33      type(one) :: tone
>     34    end type five
>     35
>     36    type(one), target        :: onev
>     37    type(two)                :: twov
>     38    type(three)              :: threev
>     39    type(four)               :: fourv
>     40    type(five)               :: fivev
>     41    type(five)               :: fivearr (2)
>     42    type(five), allocatable  :: fivedynarr (:)
>     43    logical                  :: l
>     44    integer                  :: i, j
>     45
>     46    allocate (onev%ivla (11,22,33))         ! before-allocated
>     47    l = allocated(onev%ivla)
>     48
> ------------------------------------------
>
>     gdb/ChangeLog
>
>           * amd64-tdep.c (amd64_skip_prologue): Using symbol table
>           to find the end of prologue for flang compiled binaries.
>           * arm-tdep.c (arm_skip_prologue): Likewise.
>           * i386-tdep.c (i386_skip_prologue): Likewise.
>           * producer.c (producer_is_llvm): New function.
>           (producer_parsing_tests): Added new tests for clang/flang.
>           * producer.h (producer_is_llvm): New declaration.
>
>     gdb/testsuite/ChangeLog
>
>           * gdb.fortran/vla-type.exp: Skip commands not required for
>           the Flang compiled binaries after prologue fix.

This looks good to me with two minor nits fixed.

> diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c index 
> 768fe63bdd..59f7c9f885 100644
> --- a/gdb/amd64-tdep.c
> +++ b/gdb/amd64-tdep.c
> @@ -2547,12 +2547,13 @@ amd64_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
>         = skip_prologue_using_sal (gdbarch, func_addr);
>        struct compunit_symtab *cust = find_pc_compunit_symtab 
> (func_addr);
>
> -      /* Clang always emits a line note before the prologue and another
> -      one after.  We trust clang to emit usable line notes.  */
> +      /* LLVM backend (Clang/Flang) always emits a line note before the
> +         prologue and another one after.  We trust clang to emit usable
> +         line notes.  */
>        if (post_prologue_pc
>           && (cust != NULL
>               && COMPUNIT_PRODUCER (cust) != NULL
> -           && startswith (COMPUNIT_PRODUCER (cust), "clang ")))
> +           && producer_is_llvm (COMPUNIT_PRODUCER (cust))))
>          return std::max (start_pc, post_prologue_pc);
>      }
>
> diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c index 
> 9cedcc8575..074eedb480 100644
> --- a/gdb/arm-tdep.c
> +++ b/gdb/arm-tdep.c
> @@ -60,6 +60,8 @@
>  #include "record-full.h"
>  #include <algorithm>
>
> +#include "producer.h"
> +
>  #if GDB_SELF_TEST
>  #include "gdbsupport/selftest.h"
>  #endif
> @@ -1351,7 +1353,7 @@ arm_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
>           && (cust == NULL
>               || COMPUNIT_PRODUCER (cust) == NULL
>               || startswith (COMPUNIT_PRODUCER (cust), "GNU ")
> -           || startswith (COMPUNIT_PRODUCER (cust), "clang ")))
> +           || producer_is_llvm (COMPUNIT_PRODUCER (cust))))
>         return post_prologue_pc;
>
>        if (post_prologue_pc != 0)
> diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c index 
> 9b905c1996..d9fa2b9264 100644
> --- a/gdb/i386-tdep.c
> +++ b/gdb/i386-tdep.c
> @@ -65,6 +65,7 @@
>  #include <ctype.h>
>  #include <algorithm>
>  #include <unordered_set>
> +#include "producer.h"
>
>  /* Register names.  */
>
> @@ -1847,12 +1848,13 @@ i386_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
>         = skip_prologue_using_sal (gdbarch, func_addr);
>        struct compunit_symtab *cust = find_pc_compunit_symtab 
> (func_addr);
>
> -      /* Clang always emits a line note before the prologue and another
> -      one after.  We trust clang to emit usable line notes.  */
> +      /* LLVM backend (Clang/Flang) always emits a line note before the
> +         prologue and another one after.  We trust clang to emit usable
> +         line notes.  */
>        if (post_prologue_pc
>           && (cust != NULL
>               && COMPUNIT_PRODUCER (cust) != NULL
> -           && startswith (COMPUNIT_PRODUCER (cust), "clang ")))
> +           && producer_is_llvm (COMPUNIT_PRODUCER (cust))))
>          return std::max (start_pc, post_prologue_pc);
>      }
>
> diff --git a/gdb/producer.c b/gdb/producer.c index 
> 735a928f33..fe89e7d536 100644
> --- a/gdb/producer.c
> +++ b/gdb/producer.c
> @@ -125,6 +125,18 @@ producer_is_icc (const char *producer, int *major, int *minor)
>    return false;
>  }
>
> +/* See producer.h.  */
> +
> +bool
> +producer_is_llvm (const char *producer) {
> +  if (producer == NULL || !(startswith (producer, "clang ")
> +                            || startswith (producer, " F90 Flang ")))
> +    return false;
> +
> +  return true;

I'm really not a fan of 'if (condition) return condition' type code, I'd rather see just:

  return !(producer == NULL || !(startswith (producer, "clang ")
                                 || startswith (producer, " F90 Flang ")));

> +}
> +
>  #if defined GDB_SELF_TEST
>  namespace selftests {
>  namespace producer {
> @@ -203,6 +215,22 @@ Version 18.0 Beta";
>      SELF_CHECK (producer_is_gcc (gnu_exp, &major, &minor)
>                 && major == 5 && minor == 0);
>    }
> +
> +  {
> +    static const char clang_llvm_exp[] = "clang version 12.0.0 (CLANG: bld#8)";
> +    int major = 0, minor = 0;
> +    SELF_CHECK (!producer_is_icc (clang_llvm_exp, NULL, NULL));
> +    SELF_CHECK (!producer_is_gcc (clang_llvm_exp, &major, &minor));
> +    SELF_CHECK (producer_is_llvm (clang_llvm_exp));  }
> +
> +  {
> +    static const char flang_llvm_exp[] = " F90 Flang - 1.5 2017-05-01";
> +    int major = 0, minor = 0;
> +    SELF_CHECK (!producer_is_icc (flang_llvm_exp, NULL, NULL));
> +    SELF_CHECK (!producer_is_gcc (flang_llvm_exp, &major, &minor));
> +    SELF_CHECK (producer_is_llvm (flang_llvm_exp));  }
>  }
>  }
>  }
> diff --git a/gdb/producer.h b/gdb/producer.h index 
> d8974d3814..e9bc309b0c 100644
> --- a/gdb/producer.h
> +++ b/gdb/producer.h
> @@ -52,4 +52,8 @@ extern int producer_is_gcc (const char *producer, int *major, int *minor);
>         running on Intel(R) 64, Version 18.0 Beta ....".  */  extern 
> bool producer_is_icc (const char *producer, int *major, int *minor);
>
> +/* Returns true if the given PRODUCER string is LLVM (clang/flang) or
> +   false otherwise.*/

Two whitespace after the final '.' here.

Thanks,
Andrew


> +extern bool producer_is_llvm (const char *producer);
> +
>  #endif
> diff --git a/gdb/testsuite/gdb.fortran/vla-type.exp 
> b/gdb/testsuite/gdb.fortran/vla-type.exp
> index 925c583edc..e2b8d71b4c 100755
> --- a/gdb/testsuite/gdb.fortran/vla-type.exp
> +++ b/gdb/testsuite/gdb.fortran/vla-type.exp
> @@ -33,8 +33,12 @@ set int [fortran_int4]
>
>  # Check if not allocated VLA in type does not break  # the debugger 
> when accessing it.
> -gdb_breakpoint [gdb_get_line_number "before-allocated"] 
> -gdb_continue_to_breakpoint "before-allocated"
> +# break main for Flang compiler already breaks here if 
> +![test_compiler_info "clang-*"] {
> +    gdb_breakpoint [gdb_get_line_number "before-allocated"]
> +    gdb_continue_to_breakpoint "before-allocated"
> +}
> +
>  gdb_test "print twov" " = \\\( ivla1 = <not allocated>, ivla2 = <not allocated> \\\)" \
>    "print twov before allocated"
>  gdb_test "print twov%ivla1" " = <not allocated>" \
> --
> 2.17.1


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From a9be5b9f2322b17a74554828ea37c39c6e544265 Mon Sep 17 00:00:00 2001
From: Alok Kumar Sharma <AlokKumar.Sharma@amd.com>
Date: Mon, 17 Aug 2020 17:04:11 +0530
Subject: [PATCH] Fix for incorrect breakpoint set in case of flang compiled
 binary

  Currently, GDB is not able to set a breakpoint at subprogram post
prologue for flang generated binaries. This is due to clang having
two line notes one before and another after the prologue.
  Now the end of prologue is determined using symbol table, which was
the way for clang generated binaries already. Since clang and flang
both share same back-end it is true for flang as well.

gdb/ChangeLog

      * amd64-tdep.c (amd64_skip_prologue): Using symbol table
      to find the end of prologue for flang compiled binaries.
      * arm-tdep.c (arm_skip_prologue): Likewise.
      * i386-tdep.c (i386_skip_prologue): Likewise.
      * producer.c (producer_is_llvm): New function.
      (producer_parsing_tests): Added new tests for clang/flang.
      * producer.h (producer_is_llvm): New declaration.

gdb/testsuite/ChangeLog

      * gdb.fortran/vla-type.exp: Skip commands not required for
      the Flang compiled binaries after prologue fix.

Change-Id: I5609f979315effc213feeb6dde6a01a024e0c487
---
 gdb/ChangeLog                          | 10 ++++++++++
 gdb/amd64-tdep.c                       |  7 ++++---
 gdb/arm-tdep.c                         |  4 +++-
 gdb/i386-tdep.c                        |  8 +++++---
 gdb/producer.c                         | 25 +++++++++++++++++++++++++
 gdb/producer.h                         |  4 ++++
 gdb/testsuite/ChangeLog                |  5 +++++
 gdb/testsuite/gdb.fortran/vla-type.exp |  8 ++++++--
 8 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cd950287ec..aee25787b0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2020-08-19  Alok Kumar Sharma  <AlokKumar.Sharma@amd.com>
+
+	* amd64-tdep.c (amd64_skip_prologue): Using symbol table
+	to find the end of prologue for flang compiled binaries.
+	* arm-tdep.c (arm_skip_prologue): Likewise.
+	* i386-tdep.c (i386_skip_prologue): Likewise.
+	* producer.c (producer_is_llvm): New function.
+	(producer_parsing_tests): Added new tests for clang/flang.
+	* producer.h (producer_is_llvm): New declaration.
+
 2020-08-18  Simon Marchi  <simon.marchi@efficios.com>
 
 	* linux-nat.c (linux_nat_debug_printf): New function.
diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index 768fe63bdd..59f7c9f885 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -2547,12 +2547,13 @@ amd64_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
 	= skip_prologue_using_sal (gdbarch, func_addr);
       struct compunit_symtab *cust = find_pc_compunit_symtab (func_addr);
 
-      /* Clang always emits a line note before the prologue and another
-	 one after.  We trust clang to emit usable line notes.  */
+      /* LLVM backend (Clang/Flang) always emits a line note before the
+         prologue and another one after.  We trust clang to emit usable
+         line notes.  */
       if (post_prologue_pc
 	  && (cust != NULL
 	      && COMPUNIT_PRODUCER (cust) != NULL
-	      && startswith (COMPUNIT_PRODUCER (cust), "clang ")))
+	      && producer_is_llvm (COMPUNIT_PRODUCER (cust))))
         return std::max (start_pc, post_prologue_pc);
     }
 
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 9cedcc8575..074eedb480 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -60,6 +60,8 @@
 #include "record-full.h"
 #include <algorithm>
 
+#include "producer.h"
+
 #if GDB_SELF_TEST
 #include "gdbsupport/selftest.h"
 #endif
@@ -1351,7 +1353,7 @@ arm_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
 	  && (cust == NULL
 	      || COMPUNIT_PRODUCER (cust) == NULL
 	      || startswith (COMPUNIT_PRODUCER (cust), "GNU ")
-	      || startswith (COMPUNIT_PRODUCER (cust), "clang ")))
+	      || producer_is_llvm (COMPUNIT_PRODUCER (cust))))
 	return post_prologue_pc;
 
       if (post_prologue_pc != 0)
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 9b905c1996..d9fa2b9264 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -65,6 +65,7 @@
 #include <ctype.h>
 #include <algorithm>
 #include <unordered_set>
+#include "producer.h"
 
 /* Register names.  */
 
@@ -1847,12 +1848,13 @@ i386_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
 	= skip_prologue_using_sal (gdbarch, func_addr);
       struct compunit_symtab *cust = find_pc_compunit_symtab (func_addr);
 
-      /* Clang always emits a line note before the prologue and another
-	 one after.  We trust clang to emit usable line notes.  */
+      /* LLVM backend (Clang/Flang) always emits a line note before the
+         prologue and another one after.  We trust clang to emit usable
+         line notes.  */
       if (post_prologue_pc
 	  && (cust != NULL
 	      && COMPUNIT_PRODUCER (cust) != NULL
-	      && startswith (COMPUNIT_PRODUCER (cust), "clang ")))
+	      && producer_is_llvm (COMPUNIT_PRODUCER (cust))))
         return std::max (start_pc, post_prologue_pc);
     }
  
diff --git a/gdb/producer.c b/gdb/producer.c
index 735a928f33..d25d93fcce 100644
--- a/gdb/producer.c
+++ b/gdb/producer.c
@@ -125,6 +125,15 @@ producer_is_icc (const char *producer, int *major, int *minor)
   return false;
 }
 
+/* See producer.h.  */
+
+bool
+producer_is_llvm (const char *producer)
+{
+  return ((producer != NULL) && (startswith (producer, "clang ")
+                                 || startswith (producer, " F90 Flang ")));
+}
+
 #if defined GDB_SELF_TEST
 namespace selftests {
 namespace producer {
@@ -203,6 +212,22 @@ Version 18.0 Beta";
     SELF_CHECK (producer_is_gcc (gnu_exp, &major, &minor)
 		&& major == 5 && minor == 0);
   }
+
+  {
+    static const char clang_llvm_exp[] = "clang version 12.0.0 (CLANG: bld#8)";
+    int major = 0, minor = 0;
+    SELF_CHECK (!producer_is_icc (clang_llvm_exp, NULL, NULL));
+    SELF_CHECK (!producer_is_gcc (clang_llvm_exp, &major, &minor));
+    SELF_CHECK (producer_is_llvm (clang_llvm_exp));
+  }
+
+  {
+    static const char flang_llvm_exp[] = " F90 Flang - 1.5 2017-05-01";
+    int major = 0, minor = 0;
+    SELF_CHECK (!producer_is_icc (flang_llvm_exp, NULL, NULL));
+    SELF_CHECK (!producer_is_gcc (flang_llvm_exp, &major, &minor));
+    SELF_CHECK (producer_is_llvm (flang_llvm_exp));
+  }
 }
 }
 }
diff --git a/gdb/producer.h b/gdb/producer.h
index d8974d3814..e9bc309b0c 100644
--- a/gdb/producer.h
+++ b/gdb/producer.h
@@ -52,4 +52,8 @@ extern int producer_is_gcc (const char *producer, int *major, int *minor);
        running on Intel(R) 64, Version 18.0 Beta ....".  */
 extern bool producer_is_icc (const char *producer, int *major, int *minor);
 
+/* Returns true if the given PRODUCER string is LLVM (clang/flang) or
+   false otherwise.*/
+extern bool producer_is_llvm (const char *producer);
+
 #endif
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7c624589de..0e4f6a5ce9 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-08-19  Alok Kumar Sharma  <AlokKumar.Sharma@amd.com>
+
+	* gdb.fortran/vla-type.exp: Skip commands not required for
+	the Flang compiled binaries after prologue fix.
+
 2020-08-17  Tom de Vries  <tdevries@suse.de>
 	    Tom Tromey  <tromey@adacore.com>
 
diff --git a/gdb/testsuite/gdb.fortran/vla-type.exp b/gdb/testsuite/gdb.fortran/vla-type.exp
index 925c583edc..e2b8d71b4c 100755
--- a/gdb/testsuite/gdb.fortran/vla-type.exp
+++ b/gdb/testsuite/gdb.fortran/vla-type.exp
@@ -33,8 +33,12 @@ set int [fortran_int4]
 
 # Check if not allocated VLA in type does not break
 # the debugger when accessing it.
-gdb_breakpoint [gdb_get_line_number "before-allocated"]
-gdb_continue_to_breakpoint "before-allocated"
+# break main for Flang compiler already breaks here
+if ![test_compiler_info "clang-*"] {
+    gdb_breakpoint [gdb_get_line_number "before-allocated"]
+    gdb_continue_to_breakpoint "before-allocated"
+}
+
 gdb_test "print twov" " = \\\( ivla1 = <not allocated>, ivla2 = <not allocated> \\\)" \
   "print twov before allocated"
 gdb_test "print twov%ivla1" " = <not allocated>" \
-- 
2.17.1