[gcc(refs/users/aoliva/heads/testme)] Map unpacked type to packed deduped type for debug info

[Alexandre Oliva]

https://gcc.gnu.org/g:92359793fc3d8c94a6704e518555807227b21bea

commit 92359793fc3d8c94a6704e518555807227b21bea
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Thu Jun 27 09:11:27 2024 -0300

    Map unpacked type to packed deduped type for debug info
    
    Avoid creating unnecessary copies of types in make_type_from_size.
    Cache the packed version of a biased type in TYPE_DEBUG_TYPE, so as to
    map the unpacked type to it.
    
    
    for  gcc/ada/ChangeLog
    
            * gcc-interface/utils.cc (make_type_from_size): Cache packed
            variant, and map unpacked type to it in debug info.
    
    for  gcc/testsuite/ChangeLog
    
            * gnat.dg/bias1.adb: Count occurrences of -7.*DW_AT_GNU_bias.

Diff:
---
 gcc/ada/gcc-interface/utils.cc  | 19 +++++++++++++++++++
 gcc/testsuite/gnat.dg/bias1.adb |  3 ++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/gcc-interface/utils.cc b/gcc/ada/gcc-interface/utils.cc
index d8d42f57b89..daf8d7ccdc5 100644
--- a/gcc/ada/gcc-interface/utils.cc
+++ b/gcc/ada/gcc-interface/utils.cc
@@ -1399,6 +1399,15 @@ make_type_from_size (tree type, tree size_tree, bool for_biased)
 	  || size > (Enable_128bit_Types ? 128 : LONG_LONG_TYPE_SIZE))
 	break;
 
+      /* If we've already created this type, the base type is supposed
+	 to map to it.  Check that it is what we expect.  */
+      if (TYPE_CAN_HAVE_DEBUG_TYPE_P (type)
+	  && (new_type = TYPE_DEBUG_TYPE (type))
+	  && TYPE_PRECISION (new_type) == size
+	  && ((TREE_CODE (new_type) == INTEGER_TYPE
+	       && TYPE_BIASED_REPRESENTATION_P (new_type)) == for_biased))
+	return new_type;
+
       /* The type should be an unsigned type if the original type is unsigned
 	 or if the lower bound is constant and non-negative or if the type is
 	 biased, see E_Signed_Integer_Subtype case of gnat_to_gnu_entity.  */
@@ -1414,6 +1423,16 @@ make_type_from_size (tree type, tree size_tree, bool for_biased)
       TYPE_NAME (new_type) = TYPE_NAME (type);
       TYPE_BIASED_REPRESENTATION_P (new_type) = for_biased;
       SET_TYPE_RM_SIZE (new_type, bitsize_int (size));
+
+      /* Enable us to avoid creating the same narrower type multiple
+	 times, and avoid duplication in debug information, by mapping
+	 the wider type to the narrower version.  If biasing is
+	 different, we use the narrower type for debug information.  */
+      if (TYPE_CAN_HAVE_DEBUG_TYPE_P (type)
+	  && !TYPE_DEBUG_TYPE (type)
+	  && biased_p == for_biased)
+	SET_TYPE_DEBUG_TYPE (type, new_type);
+
       return new_type;
 
     case RECORD_TYPE:
diff --git a/gcc/testsuite/gnat.dg/bias1.adb b/gcc/testsuite/gnat.dg/bias1.adb
index 016a159b692..d9a00a1aa45 100644
--- a/gcc/testsuite/gnat.dg/bias1.adb
+++ b/gcc/testsuite/gnat.dg/bias1.adb
@@ -1,6 +1,7 @@
 --  { dg-do compile }
 --  { dg-options "-cargs -g -dA -gnatws -fgnat-encodings=gdb -margs" }
 --  { dg-final { scan-assembler "DW_AT_GNU_bias" } }
+--  { dg-final { scan-assembler-times "-7.*DW_AT_GNU_bias" 1 } }
 
 procedure Bias1 is
    type Small is range -7 .. -4;
@@ -31,4 +32,4 @@ procedure Bias1 is
 
 begin
    null;
-end Bias1;
\ No newline at end of file
+end Bias1;