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Fix gimplification of ordering comparisons of arrays of bytes

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The Ada compiler now defers to the gimplifier for ordering comparisons of
arrays of bytes (Ada parlance for <, >, <= and >=) because the gimplifier
in turn defers to memcmp for them, which implements the required semantics.

However, the gimplifier has a special processing for aggregate types whose
mode is not BLKmode and this processing deviates from the memcmp semantics
when the target is little-endian.

gcc/
	* gimplify.cc (gimplify_scalar_mode_aggregate_compare): Add support
	for ordering comparisons.
	(gimplify_expr) <default>: Call gimplify_scalar_mode_aggregate_compare
	only for integral scalar modes.

gcc/testsuite/
	* gnat.dg/array42.adb, gnat.dg/array42_pkg.ads: New test.
This commit is contained in:
Eric Botcazou 2024-07-11 10:49:13 +02:00
parent 077f16b249
commit 738711703d
3 changed files with 101 additions and 5 deletions
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48
gcc/gimplify.cc
View file

@ -6728,18 +6728,56 @@ gimplify_variable_sized_compare (tree *expr_p)
static enum gimplify_status
gimplify_scalar_mode_aggregate_compare (tree *expr_p)
{
location_t loc = EXPR_LOCATION (*expr_p);
const location_t loc = EXPR_LOCATION (*expr_p);
const enum tree_code code = TREE_CODE (*expr_p);
tree op0 = TREE_OPERAND (*expr_p, 0);
tree op1 = TREE_OPERAND (*expr_p, 1);
tree type = TREE_TYPE (op0);
tree scalar_type = lang_hooks.types.type_for_mode (TYPE_MODE (type), 1);
op0 = fold_build1_loc (loc, VIEW_CONVERT_EXPR, scalar_type, op0);
op1 = fold_build1_loc (loc, VIEW_CONVERT_EXPR, scalar_type, op1);
*expr_p
= fold_build2_loc (loc, TREE_CODE (*expr_p), TREE_TYPE (*expr_p), op0, op1);
/* We need to perform ordering comparisons in memory order like memcmp and,
therefore, may need to byte-swap operands for little-endian targets. */
if (code != EQ_EXPR && code != NE_EXPR)
{
gcc_assert (BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN);
gcc_assert (TREE_CODE (scalar_type) == INTEGER_TYPE);
tree fndecl;
if (BYTES_BIG_ENDIAN)
fndecl = NULL_TREE;
else
switch (int_size_in_bytes (scalar_type))
{
case 1:
fndecl = NULL_TREE;
break;
case 2:
fndecl = builtin_decl_implicit (BUILT_IN_BSWAP16);
break;
case 4:
fndecl = builtin_decl_implicit (BUILT_IN_BSWAP32);
break;
case 8:
fndecl = builtin_decl_implicit (BUILT_IN_BSWAP64);
break;
case 16:
fndecl = builtin_decl_implicit (BUILT_IN_BSWAP128);
break;
default:
gcc_unreachable ();
}
if (fndecl)
{
op0 = build_call_expr_loc (loc, fndecl, 1, op0);
op1 = build_call_expr_loc (loc, fndecl, 1, op1);
}
}
*expr_p = fold_build2_loc (loc, code, TREE_TYPE (*expr_p), op0, op1);
return GS_OK;
}
@ -18825,7 +18863,7 @@ gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
else
goto expr_2;
}
else if (TYPE_MODE (type) != BLKmode)
else if (SCALAR_INT_MODE_P (TYPE_MODE (type)))
ret = gimplify_scalar_mode_aggregate_compare (expr_p);
else
ret = gimplify_variable_sized_compare (expr_p);

33
gcc/testsuite/gnat.dg/array42.adb Normal file
View file

@ -0,0 +1,33 @@
-- { dg-do run }
with Array42_Pkg; use Array42_Pkg;
procedure Array42 is
procedure Raise_Error_If_False (Test : Boolean; N : Positive) is
begin
if not Test then
raise Program_Error with "Test" & N'Img & " fails";
end if;
end;
begin
Raise_Error_If_False (LT2 ("12", "21"), 1);
Raise_Error_If_False (LT4 ("1234", "4321"), 2);
Raise_Error_If_False (LT8 ("12345678", "87654321"), 3);
Raise_Error_If_False (LT8 ("12345678", "87654321"), 4);
Raise_Error_If_False (LT16 ("12345678ABCDEFGH", "HGFEDCBA87654321"), 5);
Raise_Error_If_False (LT5 ("12345", "54321"), 6);
Raise_Error_If_False (LE5 ("12345", "54321"), 7);
Raise_Error_If_False (not GT5 ("12345", "54321"), 8);
Raise_Error_If_False (not GE5 ("12345", "54321"), 9);
Raise_Error_If_False (LT45 ("1234", "12345"), 10);
Raise_Error_If_False (not LT54 ("12345", "1234"), 11);
Raise_Error_If_False (LT54 ("12345", "1235"), 12);
Raise_Error_If_False (LT ("1234", "12345"), 13);
Raise_Error_If_False (not LT ("12345", "1234"), 14);
Raise_Error_If_False (LT ("12345", "1235"), 15);
end;

25
gcc/testsuite/gnat.dg/array42_pkg.ads Normal file
View file

@ -0,0 +1,25 @@
package Array42_Pkg is
subtype S2 is String (1 .. 2);
subtype S4 is String (1 .. 4);
subtype S5 is String (1 .. 5);
subtype S8 is String (1 .. 8);
subtype S12 is String (1 .. 12);
subtype S16 is String (1 .. 16);
function LT2 (A, B : S2) return Boolean is (A < B);
function LT4 (A, B : S4) return Boolean is (A < B);
function LT8 (A, B : S8) return Boolean is (A < B);
function LT16 (A, B : S16) return Boolean is (A < B);
function LT5 (A, B : S5) return Boolean is (A < B);
function LE5 (A, B : S5) return Boolean is (A <= B);
function GT5 (A, B : S5) return Boolean is (A > B);
function GE5 (A, B : S5) return Boolean is (A >= B);
function LT45 (A : S4; B : S5) return Boolean is (A < B);
function LT54 (A : S5; B : S4) return Boolean is (A < B);
function LT (A, B : String) return Boolean is (A < B);
end Array42_Pkg;